탄소중립대학원

2026년 03월 27일 금요일

Advanced Interface Engineering for High-Performance Solar Cells and Green Hydrogen

Abstract Self-assembled monolayer (SAM)-based hole-selective layers (HSLs) offer a promising route to defect-passivated and energy-aligned interfaces in perovskite organic tandem solar cells (POTSCs). However, their practical implementation remains hindered by weak anchoring to transparent conductive oxides (TCOs), leading to desorption during perovskite deposition and poor interfacial durability under polar solvent exposure. Here, we present a chemical interfacial stabilization strategy in which potassium carbonate (K2CO3) mediates the controlled deprotonation of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), forming mixed mono- and di-deprotonated species (2PACz-K) that bind strongly to indium tin oxide (ITO). The resulting SAM exhibits superior solvent resistance, improved energy-level alignment, and enhanced buried interface quality. POTSCs incorporating 2PACz-K achieve 25.10% power conversion efficiency (PCE) with a high open-circuit voltage (VOC) of 2.230 V, while retaining 80% of their initial PCE after 220 h of maximum power point (MPP) tracking under simulated 1-sun illumination. Beyond photovoltaics, the robust 2PACz-K interface is further integrated into a perovskite/organic tandem photocathode (POT-PEC), representing the first transparent, metal-free tandem PEC architecture capable of stable operation in aqueous electrolyte, delivering a photovoltage (Vph) of 2.16 V and achieving a solar-to-hydrogen (STH) conversion efficiency of 7.7%. This work establishes a versatile interfacial design paradigm that bridges photovoltaic and photoelectrochemical energy conversion. Researchers at UNIST have unveiled a novel interface engineering technique that significantly improves both the performance and durability of perovskite/organic tandem solar cells (POTSCs). Published in the February 2026 issue of Energy & Environmental Science, their study demonstrates how precise control of self-assembled monolayers (SAMs) at the molecular level can lead to more stable, high-efficiency solar devices and open new pathways for solar-driven hydrogen production. POTSCs are among the most promising photovoltaic technologies, combining different light-absorbing materials to maximize energy conversion. However, instability at the interface between the transparent electrode and the perovskite layer has long hampered their long-term reliability, especially under operational conditions. Led by Professors Jin-Young Kim and Dong-Seok Kim from the Graduate School of Carbon Neutrality, along with Professor Seung-Jae Shin from the School of Energy and Chemical Engineering, the team developed a method to chemically stabilize this critical interface. They focused on a self-assembled monolayer (SAM) known as 2PACz, which facilitates hole extraction in solar cells. Figure 1. Schematic illustration of the device structure of POTSCs with 2PACz-K and their performance. By introducing potassium carbonate (K₂CO₃), the team induced a controlled deprotonation of 2PACz molecules—partially removing hydrogen ions from their phosphonic acid groups. This process creates a mixture of mono- and di-deprotonated species (referred to as 2PACz-K), which acquire a negative charge and form stronger, more stable bonds with indium tin oxide (ITO) electrodes. This enhanced bonding results in an interface that is more resistant to solvents used during device fabrication, maintaining uniformity and stability. Devices fabricated with this chemically tailored interface demonstrated remarkable performance: perovskite solar cells achieved a power conversion efficiency (PCE) of 25.1% and an open-circuit voltage (VOC) of 2.23 V. Moreover, these cells retained over 80% of their initial efficiency after 220 hours of continuous operation under simulated sunlight, indicating substantial improvements in operational stability. The team also applied this interface engineering approach to photoelectrochemical (PEC) cells designed for water splitting. The resulting tandem PEC device exhibited a high photovoltage of 2.16 V and achieved a solar-to-hydrogen (STH) conversion efficiency of 7.7% without the need for external bias—marking a significant step toward practical, solar-driven hydrogen generation. Professor Jin-Young Kim stated, "Controlling the chemical state of interfaces at the molecular level allows us to dramatically improve both the efficiency and long-term stability of solar energy devices. This strategy offers a promising avenue for developing integrated systems that convert sunlight directly into electricity and hydrogen, supporting a sustainable energy future." The study has been supported by the National Research Foundation of Korea (NRF) and the Ministry of Science and ICT (MSIT). Journal Reference Jung Geon Son, Ha-eun Koo, Woojin Lee, et al., "Deprotonated self-assembled molecules as robust hole-selective layers for perovskite/organic tandem solar cells and photocathodes," Energy Environ. Sci., (2026).

2026년 03월 13일 금요일

UNIST Unveils New Organic Semiconductor Photoelectrode for Solar Hydrogen Production

Abstract Effective hydrogen generation in organic photoelectrochemical cells (OPECs) requires precise interfacial engineering to achieve uniform metal catalyst deposition, with enhanced water wetting and efficient charge transfer on the hydrophobic organic photoelectrode surface. Herein, we introduce n-type conjugated polyelectrolytes (CPEs) as electron transport layers to address these challenges. Two CPEs based on a naphthalene diimide backbone with distinct ionic substituents were investigated: a zwitterionic sulfobetaine (PNDI-Z3) and a quaternary ammonium iodide (PNDI-NI). Both CPEs significantly enhance surface wettability and promote uniform Pt nanoparticle deposition compared to photocathodes without CPEs. Notably, PNDI-NI enables iodide–chloride exchange with platinate precursors, accelerating the photoreduction of PtIV to PtII and ensuring strong immobilization of Pt species. Further reduction to metallic Pt0 occurs during PEC operation under applied reduction potential. Density functional theory (DFT) calculations confirm the pivotal role of iodide in facilitating this reduction pathway. The resulting PNDI-NI-modified photocathode achieves a photocurrent density of 17.7 mA cm−2 and an applied bias photon-to-current efficiency of 8.88%, representing the highest performance among reported organic photocathodes, alongside superior operational stability confirmed by chronoamperometry. These findings highlight ionically engineered CPEs as a promising strategy for coupling efficient Pt deposition and reduction with enhanced photoelectrochemical performance and durability of OPEC devices. A research team, affiliated with UNIST has unveiled the development of a long-lasting, high-efficiency organic semiconductor photoelectrode capable of solar-driven hydrogen production at a world-class level. This breakthrough marks a significant advancement toward practical, sustainable hydrogen generation using organic materials. Led by Professor Jin Young Kim of the UNIST Graduate School of Carbon Neutrality and Professor Han Young Woo of Korea University, the team engineered a novel material that enables uniform and strong attachment of platinum catalysts onto organic photoelectrodes. This innovation allows organic systems to achieve hydrogen production performance comparable to inorganic counterparts, while offering advantages in cost, flexibility, and weight. Solar hydrogen production involves illuminating a water-immersed photoelectrode, where sunlight excites the semiconductor’s active layer to generate electrons that drive water-splitting reactions, producing hydrogen gas. Platinum catalysts on the surface reduce the energy barrier for these reactions, making the process more efficient. Despite their potential benefits, organic semiconductor-based photoelectrodes have faced challenges in achieving uniform catalyst coverage and long-term stability. Their inherently hydrophobic surfaces often hinder even catalyst distribution and lead to catalyst detachment over time, limiting their commercial viability despite their low cost and flexibility. The research team developed a multifunctional polymer coating, called PNDI-NI, applied to the organic photoactive layer. Unlike conventional hydrophobic polymers, this polymer combines both hydrophobic and hydrophilic (water-attracting) properties, significantly improving surface wettability. A key feature is the presence of iodide ions within the polymer, which promote rapid growth and strong adhesion of platinum nanoparticles by facilitating the reduction of platinum ions directly onto the surface. This results in densely packed, evenly distributed platinum particles that are firmly anchored, enhancing both catalytic activity and long-term stability. Testing revealed that the coated organic photoelectrode achieved a photocurrent density of 17.69 mA/cm² under neutral conditions, with an applied bias photon-to-current efficiency (ABPE) of 8.88%. These figures represent the highest performance reported for organic-based photoelectrodes to date, approaching the efficiency of inorganic systems. This research, with first authorship by Jung Min Ha from UNIST, Shuran Xu from Korea University, and Jaehyeong Kim from UNIST, offers a scalable, solution-based platform suitable for large-area fabrication. The entire process—from polymer coating to catalyst formation—can be performed in liquid, facilitating industrial application. Moreover, the approach can be adapted to incorporate various catalytic materials beyond platinum, broadening its potential for diverse applications. Professor Kim states, "Our multifunctional polymer coating provides a simple yet effective solution for achieving uniform catalyst deposition and durable operation in organic photoelectrodes. This development offers a promising pathway toward practical solar hydrogen production." The findings of this research have been published in Advanced Energy Materials on January 6, 2026. This study has been supported by the National Research Foundation of Korea (NRF) and the Ministry of Science and ICT (MSIT). Journal Reference Jung Min Ha, Jaehyeong Kim, Shuran Xu, et al., "Conjugated Polyelectrolytes with Tunable Ionic Side Chains for Iodide-Mediated Pt Reduction in Photoelectrochemical H2 Generation," Adv. Energy Mater., (2026).

2025년 12월 01일 월요일

UNIST and PNU Launch Smart Ocean Alliance, Expanding Shared Research Infrastructure

On November 28, UNIST and Pukyong National University (PNU) have expanded their research partnership with a new agreement enabling shared access to research facilities and equipment. The agreement was signed during a joint technical exchange focused on AI applications in the marine and fisheries sector. This partnership also moves forward their ongoing efforts to establish the 'Marine & Fisheries AI Convergence Research Center,' a collaborative initiative under development since August 2025. During the exchange, researchers from both institutions reviewed ongoing projects, discussed priority areas for joint development, and explored opportunities for deeper integration of data, technology, and expertise. Presentations highlighted key fields—including Arctic maritime strategy, marine carbon-neutral technologies, and smart fisheries systems—reflecting the growing need for advanced AI solutions across emerging ocean industries. UNIST faculty offered perspectives on strategic technologies for the maritime sector. Professor Chang-Hun Lee (School of Business Administration) outlined port strategies in preparation for future Arctic Sea Route access, while Professor Hankwon Lim (Graduate School of Carbon Neutrality) presented pathways for industrial carbon reduction. From PNU, Professors Seong-Hoon Kim and Eun-Joon Chun proposed new research directions that link marine logistics with SMR and materials-processing technologies. As part of the collaboration, the two institutions signed an agreement to mutually open their research facilities, experimental equipment, and training spaces under the same conditions. The arrangement will provide UNIST researchers access to PNU’s maritime and training infrastructure, while PNU researchers will gain use of UNIST's advanced analytical and testing platforms—significantly expanding research capacity and efficiency for both sides. Building on this agreement, UNIST and PNU plan to broaden cooperation across key strategic fields, including ocean environmental monitoring, marine robotics, resource exploration, and hydrogen and carbon-neutral technologies. Joint initiatives will also extend to policy research, such as maritime industry finance and technology strategies for Arctic route development, helping strengthen the broader marine research ecosystem across the southeastern region. UNIST President Chong Rae Park emphasized the significance of the partnership, noting, "This collaboration marks an important step in expanding UNIST’s research network across the marine and AI landscape. By connecting our capabilities with a broader ocean science ecosystem, we aim to scale this partnership from the southeastern region of Korea to global marine and fisheries research." PNU President Sang-Hoon Bae added, "By combining the strengths of both institutions, we expect to accelerate innovation in the marine industry and deliver meaningful solutions to emerging challenges."

2025년 06월 11일 수요일

Mechanochemical Approach for Low-Temperature CO2 Capture and Conversion

Abstract Developing a direct carbon dioxide (CO2) capture and methanation method is one of the most important challenges to achieving carbon neutrality. However, converting CO2 into methane (CH4) kinetically requires the activation of stable CO2 at high temperatures (300–500 °C), while the CO2-to-CH4 conversion thermodynamically favours low temperatures. Here we report an efficient mechanochemical CO2 capture and conversion under mild conditions (65 °C). Using commercial zirconium oxide (ZrO2) and nickel catalysts, the mechanochemical CO2 capture capacity was 75-fold higher than the conventional thermochemical process. The mechanochemical CO2 conversion reached a nearly quantitative CO2 conversion (99.2%) with CH4 selectivity (98.8%). We determined that repeatedly induced abundant oxygen vacancies on ZrO2 by dynamic mechanical actions are responsible for efficient CO2 capture and, thus, subsequently spontaneous methanation. A pioneering approach has been developed to convert carbon dioxide (CO₂) into methane (CH₄)—the main component of natural gas—at room temperature. Traditionally, this process requires high temperatures above 300°C, making it energy-intensive and costly. The new method, which involves just rotating raw materials with steel balls, was recently published in Nature Nanotechnology, a top journal in nanoscience. Led by Professor Jong-Beom Baek in the School of Energy and Chemical Engineering and Professor Hankwon Lim of the Graduate School of Carbon Neutrality at UNIST, the research team announced that they have successfully created a mechanochemical process, capable of converting CO₂ into CH₄ efficiently at just 65°C. This simpler, low-energy approach could accelerate the shift toward a sustainable, carbon-neutral future. The process uses a ball mill—a device containing small steel balls of a few millimeters in diameter—filled with catalysts and raw materials. As the mill rotates, collisions and friction activate the catalyst surfaces, enabling CO₂ to be captured and react with hydrogen to produce methane. Remarkably, the team achieved a 99.2% conversion rate of CO₂ at this low temperature, with 98.8% of the reacted CO₂ turning directly into methane, rather than byproducts. The process also proved highly effective in continuous operation, maintaining an 81.4% reaction participation rate and 98.8% methane selectivity even at 15°C, below room temperature. This demonstrates its potential for scalable industrial use. Figure 1. Schematic image, illustrating the mechanochemical CO2 capture and conversion. The process leverages commercially available zirconium oxide (ZrO₂) and nickel catalysts, which are both affordable and widely used in industry. Nickel helps split hydrogen molecules, while zirconium oxide enhances CO₂ activation. The mechanical impacts within the ball mill induce oxygen vacancies in zirconium oxide, trapping CO₂ molecules and enabling their reaction with hydrogen on the nickel catalyst to produce methane. Economic assessments suggest that because the process operates at low temperatures and utilizes readily available catalysts without extensive pre-treatment, it can significantly reduce equipment and operational costs. Professor Lim explained, "When powered by renewable energy sources, like wind or solar, this method could cut energy consumption in half compared to conventional thermochemical processes." Professor Baek highlighted the practical significance by saying "This technology makes it possible to convert CO₂ directly into fuel on-site, without the need for high-temperature, high-pressure equipment. It not only reduces carbon emissions but also lowers infrastructure and transportation costs, offering a promising pathway toward carbon neutrality." This research was conducted in collaboration with Professor Qunxiang Li of the University of Science and Technology of China (USTC), with support from the National Research Foundation (NRF) of Korea and the UNIST Carbon Neutrality Demonstration and Research Center. Journal Reference Runnan Guan, Li Sheng, Changqing Li, et al., "Mechanochemical carbon dioxide capture and conversion," Nat. Nanotechnol., (2025).

2025년 05월 19일 월요일

New Thin-Film Material Achieves Both High Efficiency and Durability in Tandem Solar Cells

Abstract Perovskite/organic tandem solar cells (POTSCs) are promising candidates for surpassing the Shockley-Queisser limit through reduction of thermalization losses. However, wide bandgap perovskite solar cells (WBG PSCs), which function as top cells of POTSCs, still suffer from significant open-circuit voltage (VOC) losses, limiting efficiency improvement of POTSCs. Here, a multi-functional hole-selective layer (mHSL) is reported via blending two functionalized self-assembled monolayer (SAM) molecules: (4-(3,6-diiodo-9H-carbazol-9-yl)butyl)phosphonic acid (36ICzC4PA) and (4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl)phosphonic acid (36MeOCzC4PA). The blending of the two molecules plays multiple roles: i) Suppressing micelle formation of SAM molecules, ii) optimizing energy level alignment with homogeneous and highly covered SAMs, iii) enhancing crystallinity and orientation of perovskite through interaction with SAM materials, and iv) suppressing both lattice strain and phase segregation. Implementing mHSL on WBG PSCs enables a power conversion efficiency (PCE) of 18.85% with a notable VOC of 1.366 V. When integrated into POTSCs, the PCE reached 24.73% (certified 24.19%) with record-high VOC and fill factor (FF) of 2.216 V and 84.07%, respectively. Furthermore, POTSCs exhibit excellent photo- and thermal stabilities, retaining ≈80% of their initial PCEs after maximum power point (MPP) tracking under 1-sun illumination in ambient conditions for 305 h or exposure to 65 °C in N2 conditions for 500 h. A novel thin-film material, capable of simultaneously enhancing the efficiency and durability of tandem solar cells has been developed. Led by Professor BongSoo Kim from the Department of Chemistry at UNIST, in collaboration with Professors Jin Young Kim and Dong Suk Kim from the Graduate School of Carbon Neutrality at UNIST, the team announced the development of a multi-functional hole-selective layer (mHSL) designed to significantly improve the performance of perovskite/organic tandem solar cells (POTSCs). Tandem solar cells are advanced photovoltaic devices that stack two different types of cells to absorb a broader spectrum of sunlight, thereby increasing overall energy conversion efficiency. Among these, combinations of perovskite and organic materials are particularly promising for producing thin, flexible solar panels suitable for wearable devices and building-integrated photovoltaics, positioning them as next-generation energy sources. The research team successfully developed a hole-transport layer (HTL) by blending two self-assembled molecules, achieving a record open-circuit voltage (VOC) of 2.216 V and a power conversion efficiency (PCE) of 24.73%. The VOC, which reflects the maximum voltage the cell can produce without current flow, is a critical indicator of device performance. This efficiency level is among the highest ever recorded for perovskite-organic tandem solar cells globally. Moreover, the device maintained over 80% of its initial efficiency after prolonged exposure to high temperatures of 65°C and continuous illumination, demonstrating excellent long-term stability. The newly developed HTL is carefully engineered to align its energy levels with the perovskite active layer, selectively extracting holes while blocking electrons, thereby reducing charge recombination losses. Efficient charge extraction is essential because, after light absorption, electrons and holes must reach their respective electrodes to generate current; misaligned energy levels cause charge loss and reduced efficiency. Additionally, this HTL reduces interface defects that hinder charge transport and stabilizes the crystal structure, thanks to the strong chemical bonds formed between the substituents of the self-assembled molecules—36ICzC4PA and 36MeOCzC4PA—and the metal ions within the perovskite layer. The self-assembly property of these molecules ensures a uniform, ultra-thin coating over large areas, simplifying manufacturing processes and facilitating scalable production for commercialization. Professor Kim commented, "By developing a self-assembled hole transport layer that improves charge extraction, interface stability, and structural durability, we have made a significant leap forward in enhancing the performance of tandem solar cells. This development brings us closer to realizing thin, flexible, and high-efficiency next-generation solar panels for practical applications." This research involved first authors Jung Geon Son and Shahid Ameen and was published in Advanced Energy Materials on April 8, 2025. The study was supported by the National Research Foundation of Korea (NRF) through the Ministry of Science and ICT (MSIT). Journal Reference Jung Geon Son, Shahid Ameen, Jina Roe, et al., "Exceeding 2.2 V Open-Circuit Voltage in Perovskite/Organic Tandem Solar Cells via Multi-Functional Hole-Selective Layer," Adv. Energy Mater., (2025).

2025년 04월 30일 수요일

Innovative All-Organic Photoelectrode Developed to Enhance Eco-Friendly Solar Hydrogen Production

Abstract Organic photoelectrochemical (OPEC) cells are efficient at generating photocurrents but face significant challenges in long-term stability due to the incompatibility of metal oxide charge transport layers with organic photoactive materials and their pH sensitivity. To overcome these issues, we developed an all-organic photoanode incorporating n-type self-assembled monolayers (SAMs) with imide core modifications, which optimize the work function of the ITO substrate, improving charge transfer and the onset potential (Vonset). The addition of a hole-transporting p-type conjugated polyelectrolyte (TPAFS-7TMA) further enhances hole transport and water wettability. This photoanode, designed for ascorbic acid oxidation, achieved a Vonset of 0.25 VRHE and a photocurrent density (Jph) of 7.92 mA cm–2 at oxidation potential and retained 90% of its initial Jph over 2 h under 1 sun irradiation. This all-organic design effectively addresses the limitations of conventional OPEC cells, providing a stable and efficient alternative for durable OPEC systems. We developed a stable and efficient all-organic photoanode for OPEC cells, utilizing imide-modified n-type SAMs and a p-type conjugated polyelectrolyte to enhance charge transfer, water wettability, and durability, achieving significant performance improvements. A research team, affiliated with UNIST has unveiled a new technology, capable of making solar-powered hydrogen production more stable and cost-effective. This breakthrough involves constructing the entire photoelectrode, a key component in hydrogen generation, entirely from organic materials—overcoming longstanding issues of corrosion and delamination associated with conventional organic photoelectrodes. Led Professor Jin Young Kim from the Graduate School of Carbon Neutrality at UNIST, in collaboration with Professor Jae Sung Lee from the School of Energy and Chemical Engineering, and Professor Han Young Woo from the Department of Chemistry at Korea University, the team announced that they have developed an all-organic photoanode that eliminates the need for metal oxides. Solar hydrogen production operates on the principle that when sunlight irradiates a photoelectrode submerged in water, electrochemical reactions occur on its surface, splitting water molecules into hydrogen and oxygen. To maximize efficiency, these reactions typically occur in acidic or alkaline solutions. However, conventional organic photoelectrodes often rely on metal oxide charge transport layers, which are prone to corrosion or delamination in such environments, resulting in compromised stability. Figure 1. Schematic image, illustrating the structure and performance of the highly stable all-in-one photoelectrode. To address these challenges, the researchers developed a fully organic photoelectrode utilizing n-type self-assembled monolayers (SAMs) and p-type conjugated polymer electrolytes. The n-type SAM replaces metal oxides, enhancing adhesion between the substrate and the organic active layer while significantly improving electron transfer efficiency. The p-type polymer layer on the surface selectively transports holes and increases surface hydrophilicity, thereby improving contact with the aqueous solution. The newly developed all-organic photoelectrode demonstrated a high photocurrent density of 7.92 mA/cm² in an acidic environment containing ascorbic acid. This performance metric directly correlates with hydrogen production rate. Remarkably, the device maintained over 90% of its initial performance after two hours of continuous illumination without the need for protective coatings or metal encapsulation, confirming its exceptional stability. Professor Kim stated, "This research fundamentally resolves the pH sensitivity and delamination issues that have historically limited organic photoelectrodes," adding, "Applying n-type self-assembled monolayers to the photoanode for the first time and constructing a fully organic photoelectrode demonstrates the practical viability of entirely organic systems." He further noted, "This technology not only advances eco-friendly hydrogen production but also opens avenues for developing diverse organic-based photoelectrochemical devices." The study was conducted by Dr. Jiwoo Yeop and Dr. Jin Uk Lee from UNIST, along with Jae Hoon Son (Combined M.S. and Ph.D., Department of Chemistry) from Korea University, serving as the first authors. The research was published in the March 14 issue of ACS Energy Letters and was supported by the National Research Foundation of Korea (NRF) under the Ministry of Science and ICT. Journal Reference Jiwoo Yeop, Jae Hoon Son, Jin Uk Lee, et al., "Realization of All-Organic Photoanodes for Photoelectrochemical Cells," ACS Energy Lett., (2025).

2025년 01월 07일 화요일

Professor Seungho Park-Lee Recognized by Ulsan Mayor for Reducing 10,000 Disposable Cups with UlsanCup Initiative

Professor Seungho Park-Lee, affiliated with the Department of Design and the Graduate School of Carbon Neutrality at UNIST, has been awarded the Ulsan Mayor's Commendation Award for his exemplary work in launching and revitalizing the UlsanCup initiative. His efforts have led to a significant reduction of 11,590 disposable cups used over a span of approximately ten months within the Ulsan Metropolitan City Hall and UNIST campuses. A key highlight of Professor Lee's initiative was the development of the world's first life cycle assessment (LCA) website specifically designed for multiple-use drinking cups. This innovative platform, created in collaboration with a team, led by Professor Hankwon Lim from the Graduate School of Carbon Neutrality and the School of Energy and Chemical Engineering at UNIST, enables users to assess the environmental footprint of these cups, while also helping the general public to better understand and evaluate the disposable waste and predict carbon dioxide emissions. The UlsanCup was initially introduced near Ulsan Metropolitan City Hall in December 2022 and expanded to UNIST in April 2023. Notably, it boasts an impressive recovery rate exceeding 90% through a straightforward return system, making it both economical and practical, as it does not require expensive return equipment. To enhance user convenience, the research team has refined the QR scanner cover and improved the user interface of the return app. Additionally, they have identified practical and innovative service concepts, such as ' Group deposit ' and ' Collection Incentive ,' and are currently pursuing a patent for these ideas. The LCA website is publicly accessible on the official website of Ulsan Metropolitan City ( https://www.ulsan.go.kr/lca/ ), allowing users to evaluate environmental impact effortlessly. Users can input details such as material type, weight, recovery rate, and washing energy consumption to calculate carbon emissions and waste generation, establishing it as a user-friendly tool for measuring environmental effects. This website also plays a crucial role in shaping Ulsan Metropolitan City's multiple-use cup policy. Through data analysis, officials can assess the feasibility of adding new locations or increasing user participation. An official from Ulsan Metropolitan City stated, "The UlsanCup will be managed according to detailed plans aimed at scientifically reducing carbon emissions and waste." The research team has made their analysis algorithm open source on the mentioned website, providing an opportunity for other researchers to further develop and expand the algorithm. “There are environmental consulting firms that conduct comprehensive evaluations, yet it is rare for them to disclose their algorithms,” remarked Professor Hankwon Lim. “This transparency exemplifies UNIST’s commitment to the spirit of ‘First in Change,’ prioritizing the creation and sharing of knowledge.” Professor Lee emphasized, "The UlsanCup Project offers a scientific solution to the challenges of carbon emissions and waste management grounded in empirical data. UNIST is dedicated to propagating sustainable environmental technologies and resource circulation systems in the global market." This research initiative is part of the ' Project Utilizing Science and Technology for Local Community Problem-Solving ,' co-supported by the Ministry of Science and ICT (MSIT) and the Ministry of Interior and Safety (MOIS) in 2023. The project has garnered attention as the Living Lab Research Project , aimed at improving citizens' daily lives through science and technology, with funding provided by the MSIT in collaboration with local governments.

2024년 11월 15일 금요일

New Study Unveils the Optimal Concentration for Effective CO₂ Capture in Gas Hydrates

Abstract To mitigate global warming, the paramount imperative lies in curbing the emission of CO2. The guest replacement method is a prominent carbon-neutral technological advancement that involves injecting CO2 into natural gas hydrate layers to accomplish the dual objectives of energy production and carbon storage. In this study, the guest dynamics in the CH4 – flue gas replacement process were examined, and the impacts of the N2 concentration of the injected gas were systematically analyzed. A powder X-ray diffraction analysis of the cage-specific guest distributions after CH4 − CO2 (20 %) + N2 (80 %) replacement revealed that CH4 production increased in both the large and small cages compared to the CH4 – CO2 replacement. This enhancement was attributed to the N2 molecules participating in both cages. However, this simultaneously led to a decrease in CO2 storage potential, indicating a ‘complementary’ relationship for CH4 production and a ‘competitive’ one for CO2 storage with respect to CO2 and N2. In situ Raman spectroscopy revealed that the introduction of N2 resulted in a deceleration of CO2 storage kinetics. Guest composition measurements after replacement showed an upward trend in CH4 production and a simultaneous decline in CO2 storage as the N2 composition increased. Notably, an intriguing correlation was established between the CO2/N2 ratios for the injected gas and the replaced hydrates, exhibiting a strong alignment with a simple first-order equation. The findings not only contribute to a deeper understanding of the CH4 − CO2 + N2 replacement technique but provide practical insights for its application in real-world scenarios. A research team led by Professor Yongwon Seo from the Graduate School of Carbon Neutrality at UNIST has successfully elucidated the replacement behavior and mechanisms associated with varying concentrations of carbon dioxide (CO2) in guest replacement technology for natural gas hydrates (NGHs). Their research also proposes the optimal concentration of injected gas mixtures to maximize natural gas production while enhancing CO2 capture. This guest replacement process facilitates the extraction of natural gas from NGHs and its replacement with CO2, a known greenhouse gas. The team conducted experiments using flue gas—also known as exhaust gas or stack gas—a mixture of nitrogen (N2) and CO2 emitted from industrial combustion processes, such as those in power plants and boilers. Utilizing this flue gas for injection allows for direct introduction of CO₂ into NGH layers without the need for prior CO₂ separation. However, because N2 occupies space within NGHs instead of CO₂, further investigation is warranted to optimize this process. Figure 1. Schematic image, showing the guest replacement process simulation, utilizing flue gas. In this study, the dynamics of gas guest distributions in the CH₄–flue gas replacement process were explored. Systematic analysis revealed a trade-off where increased concentrations of N₂ not only delayed the rates of CO₂ storage but also CH₄ production. The research team measured replacement behavior, natural gas production, and CO₂ storage using various concentrations of flue gas, ultimately discovering a correlation equation linking the concentration ratio of CO₂ stored in gas hydrates to the concentration of the injected gas. Their findings indicate that natural gas production and CO₂ storage efficiency are optimized at a CO₂ concentration of 64%. "The results of this study are expected to provide guidelines for utilizing natural gas hydrates, which are distributed around the world, as reservoirs for greenhouse gases and as sources of clean energy," remarked first author Dr. Junghoon Mok from UNIST who currently is Assistant Professor at Kyonggi University. Researchers Jonghyuk Lee and Wonjung Choi also contributed to this study. The findings were published online on October 10 in Renewable & Sustainable Energy Reviews, a leading journal in green energy technology, and are anticipated for official publication. Journal Reference Junghoon Mok, Jonghyuk Lee, Wonjung Choi, and Yongwon Seo, "Complementary and competitive dynamics of CO2 and N2 in CH4 – Flue gas replacement within natural gas hydrates," Renew. Sustain. Energy Rev., (2024).

2024년 10월 18일 금요일

UNIST Signs Cooperation MoU with PI Advanced Materials Co., Ltd.

UNIST Graduate School of Carbon Neutrality will work with PI Advanced Materials Co., Ltd., the world's largest polyimide film market share, to develop technology to reduce carbon emissions. On October 16, the Graduate School of Carbon Neutrality and PI Advanced Materials Co., Ltd. entered into a business agreement to realize carbon neutrality. The two organizations worked together in various fields, including the development of carbon neutrality policies, joint research, and human resources development, aiming to commercialize carbon neutrality technology. The Graduate School of Carbon Neutrality at UNIST currently operates four research groups: △ Environmental Management and Policy Research △ Carbon dioxide capture, utilization, and storage (CCUS) technology △ Hydrogen and renewable energy technology. Based on its research capabilities, it plans to accelerate technology development in cooperation with PI advanced materials and actively apply research results to industrial sites. The two organizations plan to combine carbon-neutral technology with advanced materials to lead environmental issues and innovation. They plan to strengthen their global competitiveness by consolidating policy and technological cooperation and strive to realize carbon neutrality. "Cooperation with PI Advanced Materials Co., Ltd. will be an important milestone in the commercialization and research of carbon neutral technology," said Yongwon Seo, Head of Graduate School of Carbon Neutrality. "We hope that concrete results will be achieved starting with the agreement and that we will lead to a big change for a sustainable future." "Through cooperation with UNIST, we will strengthen policy and technological cooperation to realize carbon neutrality, which will mark a new turning point in achieving corporate carbon neutrality goals," said Heejoon Ham, Senior Vice President of PI Advanced Materials Co., Ltd. "We expect each other to grow in various aspects such as policy development, technological innovation, and talent training."

2024년 08월 09일 금요일

Cost-Effective Tin Chloride Boosts Efficiency of Perovskite Solar Cells

Abstract The prominent chemical bath deposition (CBD) method leverages tin dioxide (SnO2) as an electron transport layer (ETL) in perovskite solar cells (PSCs), achieving exceptional efficiency. The deposition of SnO2, however, can lead to the formation of oxygen vacancies and surface defects, which subsequently contribute to performance challenges such as hysteresis and instability under light-soaking conditions. To alleviate these issues, it is crucial to address heterointerface defects and ensure the uniform coverage of SnO2 on fluorine-doped tin oxide substrates. Herein, the efficacy of tin(IV) chloride (SnCl4) post-treatment in enhancing the properties of the SnO2-ETL and the performances of PSCs are presented. The treatment with SnCl4 not only removes undesired agglomerated SnO2 nanoparticles from the surface of CBD SnO2 but also improves its crystallinity through a recrystallization process. This leads to an optimized interface between the SnO2-ETL and perovskite, effectively minimizing defects while promoting efficient electron transport. The resultant PSCs demonstrate improved performance, achieving an efficiency of 25.56% (certified with 24.92%), while retaining 95.84% of the initial PCE under ambient storage conditions. Additionally, PSCs treated with SnCl4 endure prolonged light-soaking tests, particularly when subjected to quasi-steady-state-IV measurements. This highlights the potential of SnCl4 treatment as a promising strategy for advancing PSC technology. The commercialization of perovskite solar cells (PSCs) is anticipated to accelerate through the use of inexpensive tin (IV) chloride (SnCl4). A research team jointly led by Professor Dong Suk Kim from the Graduate School of Carbon Neutrality at UNIST and Dr. Yimhyun Jo from the Korea Institute of Energy Research (KIER) has significantly enhanced the stability of PSCs. By applying IV chloride to a layer of tin oxide, the team has improved the stability of these solar cells. To achieve high efficiency in PSCs, it is crucial to manage surface defects in the electron transport layer (ETL)—a thin film that facilitates the efficient extraction and transport of electrons. Such defects greatly influence both the stability and efficiency of PSCs. Figure 1. Schematic illustration of the SnCl4 treatment process applied to the SnO2 ETL prepared via the CBD method. The research team dissolved IV SnCl4 in water and applied it to the oxide layer. This process has resulted in the complete oxidation of the upper layer of tin oxide and facilitated recrystallization, leading to enhanced electron mobility. Figure 2. (Top) Storage stability of the PSCs tested in ambient condition (25 °C, 25% RH), (Center) Thermal stability of the PSCs subjected to thermal stress at 65 °C (25% RH). QSS J–V curves of the (Bottom) control- and d) target-PSCs. Chemical bath deposition (CBD) is a widely used approach that leverages tin dioxide (SnO2) as the electron transport layer (ETL) in PSCs, achieving exceptional efficiency. However, the deposition of SnO2 can lead to the formation of surface defects, which are inevitable due to the incomplete oxidation of tin. Addressing these defects post-film formation is vital for achieving both high efficiency and long-term stability. For the successful commercialization of PSCs, it is essential to pass various certification tests. The research team demonstrated the effectiveness of their approach by enhancing the electron transport layer (ETL) and showcasing long-term resistance to heat and ultraviolet exposure. Professor Kim stated, "Through this study, we succeeded in suppressing the aggregation of tin oxides and improving their crystallinity," adding, "This technology will play a pivotal role in enhancing the stability of solar cells." Researchers Ji Won Song and Dr. Yun Seop Shin noted, "We expect to positively impact the energy industry by simultaneously achieving high efficiency, durability, and low cost with affordable IV SnCl4." The findings of this research have been published online in Advanced Energy Materials on July 3, 2024. Journal Reference Ji Won Song, Yun Seop Shin, Minjin Kim, et al., "Post-Treated Polycrystalline SnO2 in Perovskite Solar Cells for High Efficiency and Quasi-Steady-State-IV Stability," Adv. Energy Mater., (2024).