EES catalysis最新文献

Renewable-powered CO₂ electrolysis (CO₂E) is a promising strategy to reduce greenhouse gas emissions by transforming CO₂ into valuable feedstocks. While recent studies in this field have focused on developing efficient catalyst materials or electrolyzer engineering, the operating temperature's effect has not been systematically examined for zero-gap electrolyzers. To examine the effects of operating temperature, a systematic investigation was conducted using zero-gap (MEA) Cu-based GDEs across a range from room temperature to 80 °C. Our results indicate that increasing the temperature improves CO₂ mass transport, ionic conductivity, and water management, allowing for high catalytic activity toward CO₂E. At operating temperatures greater than 50 °C, selectivity shifted substantially towards CO, with surface enhanced infrared absorption spectroscopy (SEIRAS) showing a concomitant decrease in surface CO coverage at and above this temperature. As commercial electrolyzers will operate at elevated temperatures due to ohmic heating, they may produce a significantly different product distribution than the room-temperature electrolysis prevalent in the literature. Experiments at elevated temperatures demonstrated improved results for CO₂E with industrially relevant current densities (150 mA cm⁻²) over an extended operational period (>200 hours). Additionally, we found that the heating method strongly affects product selectivity and the electrolyzer's performance, emphasizing the need to ensure proper heating while working under these reaction systems.

Piezo-(photo)catalytic technologies offer a promising solution for accelerating energy diversification and addressing environmental pollution by converting mechanical and light energy into chemical energy. The application of piezo-(photo)catalytic technology not only meets the demands of a growing market but also contributes to environmental preservation. In this review, we summarize recent advancements in synthesizing value-added chemicals through piezo-(photo)catalytic technology, highlighting the principles of piezotronics and piezo-phototronics. We examine the fundamental processes involved in energy conversion and discuss the advantages of synthesized value-added chemicals using piezocatalytic technology. We explore different chemistries and reaction pathways, and categorize piezoelectric semiconductors based on performance in piezo-photocatalysis. Finally, we identify prospects, challenges, and potential solutions for future research and development in value-added chemical synthesis using piezo-(photo)catalytic technology.

CO₂ electrolysis in membrane-electrode assemblies (MEAs) has come up one step closer to commercialization through compact cell design and high-current operation. However, while both cathodic and anodic reactions significantly affect the overall cell efficiency, the anodic oxygen evolution reaction (OER) has received much less attention compared to the cathodic CO₂ reduction reaction (CO₂RR). More importantly, OER electrocatalysts for CO₂ electrolysis are being developed independently of system design, despite their interconnected nature. Since the aqueous testing systems in which OER electrocatalysts have been developed do not reflect the complex local anodic environment inside an anion exchange membrane CO₂ electrolyzer (AEMCE), electrocatalysts sensitive to local chemistry may have been optimized for incorrect operating conditions. Based on a comprehensive understanding of the local anodic environment inside the AEMCE, in this perspective, we scrutinize the limitations of conventional OER electrocatalyst development resulting from the discrepancy between aqueous testing systems and the existing MEA-type systems. To bridge these gaps, we suggest three electrocatalyst evaluation platforms that integrate reference electrodes to existing AEMCEs for reliable and genuine OER electrocatalyst assessment.

Zinc–air batteries have attracted more attention due to their high energy density, high safety, low cost, and environmental friendliness. Nevertheless, sluggish oxygen reaction kinetics at the air electrode seriously compromises their power density and cycling stability. As one of the main components, the catalyst significantly impacts the performance of zinc–air batteries. Finding high-performance bifunctional catalysts for both the oxygen reduction reaction and oxygen evolution reaction is of great importance for the practical application of zinc–air batteries. In this review, the history, merits and challenges of zinc–air batteries are introduced, the working principle of zinc–air batteries and the mechanisms of ORR and OER in air electrodes are analyzed deeply, and the research status of bifunctional catalysts that promote both ORR and OER kinetics is systematically reviewed. Finally, the pending problems that need to be solved in future research and the practical application of bifunctional catalysts in zinc–air batteries are discussed. This review aims to provide a valuable reference for the development of bifunctional catalysts for zinc–air batteries.

Climate change is a critical global challenge that requires urgent action to reduce greenhouse gas emissions, including carbon dioxide (CO₂). While essential efforts are being made to reduce emissions by developing new manufacturing processes, it is also crucial to scrutinize sustainable uses for the CO₂ that is already produced in excess. The electrochemical CO₂ reduction reaction (eCO₂RR) is a highly promising and versatile approach for converting CO₂ into valuable base chemicals and fuels, effectively decarbonizing the chemical industry. New methodologies and electrocatalysts in this area are increasingly being investigated, emphasizing the necessary transition to a more sustainable future. In this review, we focus on the eCO₂RR coupled with incorporation in organic or inorganic reactants towards key industrial compounds such as carboxylic acids, ureas and dimethyl carbonate. We provide a broader context by outlining the current industrial synthesis methods of the envisioned compounds. Recent work is summarized in tables for quick comparison while innovations and improvements regarding sustainability and applicability are addressed in more detail.

Effectively engaging light to induce catalytic activity requires the careful selection of a catalyst support with appropriate and beneficial properties. On this basis, black, plasmonic TiN was employed as a Ni catalyst support for the CO₂ methanation reaction under illuminated-only conditions. The positive effects of light illumination were found to be defined by the Ni deposit size and the Ni–TiN interaction. At a high Ni loading (40 wt%, 70 wt%), simulated sunlight induces plasmonic heating through the TiN support which is sufficient to initially in situ reduce the Ni deposits and initiate CO₂ methanation. Photothermal effects from TiN and the metallic Ni, combined with reaction exothermicity, then continue to further reduce the Ni and amplify the methanation reaction. At a lower Ni loading (10 wt%), the Ni deposits are smaller and more dispersed. In this case, the topmost Ni deposit surfaces are more strongly influenced by the TiN support due to their closer proximity to the metal–support interface. DFT calculations revealed that this condition can facilitate the migration of light induced plasmonic hot charge carriers from the TiN towards the exposed Ni surface, altering the surface charge of the Ni. The adsorption strength of *CO is subsequently enhanced to enable further reaction rather than desorption as product, thereby boosting CH₄ selectivity. The findings discern between the different phenomena (plasmonic heating and hot electron migration) invoked by plasmonic excitation and offer new insight on the contribution these phenomena make to governing catalyst activity and selectivity.

Electrochemical conversion of nitrate into benign dinitrogen is a promising solution for water purification and environmental remediation. The development of environmentally friendly electrocatalysts possessing excellent catalytic activity and stability has attracted increasing attention. Herein, a 1D hierarchical architecture with uniformly dispersed Fe₃C nanoparticles confined in multichannel nitrogen-doped carbon fibers (Fe₃C/MNCFs) is reported as a highly efficient NO₃RR electrocatalyst. Fe₃C/MNCFs-800 demonstrates a nitrate conversion of 90.9%, an N₂ selectivity of 99.53%, and up to 15 cycles of electrocatalytic stability. The excellent electrocatalytic activity is proposed to be mainly due to the multichannel fibrous architecture beneficial for exposing more active sites and facilitating mass diffusion. Moreover, the strong interaction between active species and fibrous support guarantees the chemical stability and long cycle life. This work provides a reference for the development of high-performance noble-metal-free electrocatalysts for eco-friendly nitrate reduction.

Electrocatalytic nitrate reduction has been identified as a promising technology for green ammonia production, allowing the conversion of harmful nitrate from wastewater into valuable ammonia using renewable electricity under ambient conditions. Developing advanced electrocatalysts is of paramount significance for improving the ammonia production efficiency in this process. Recently, Cu-based catalysts have been widely investigated in ammonia production via nitrate reduction due to their rapid reduction reaction kinetics, strong electrical conductivity, and ability to inhibit the hydrogen evolution reaction. Meanwhile, the reaction mechanism and computational and experimental methods have been extensively discussed to understand the theory behind the favourable properties of Cu-based catalysts. In this review, we focus on Cu-based catalysts, aiming to provide insights into the latest developments, reaction mechanisms, and state-of-the-art analysis methods for intermediates and products of nitrate reduction to ammonia. Future outlooks and remaining challenges are presented to provide guidance for advancing from experimental explorations to practical applications.

Ammonia is a key small molecule for manufacturing nitrogen-based fertilizers and organic chemicals and equally important for renewable energy storage and conversion. The available Haber–Bosch ammonia synthesis process using fused iron catalysts operated under harsh conditions is, however, unsustainable. The development of alternative and more efficient approaches to sustainable ammonia production has garnered much attention recently. Most of the prior work has been devoted to the investigation of Fe, Ru or Co-based metal catalysts for ammonia synthesis. In comparison, there are very limited studies on group 4–7 transition metals, because they are prone to form metal nitrides, which are difficult to hydrogenate to ammonia. This mini-review summarizes recent advances in activating these metals for heterogeneous ammonia synthesis. We show that the potential properties of group 4–7 transition metals for ammonia synthesis should be revisited, which may lead to the development of more efficient materials or chemical processes for ammonia production under mild conditions.

Minimizing the power-specific iridium loading in polymer electrolyte water electrolysis (PEWE) is essential for the commercialization and upscaling of this technology. However, decreasing the iridium loading can severely affect performance and stability. Microporous layers (MPL) can overcome some of these issues by maximizing catalyst utilization and increasing cell efficiency. In this study, we combined advanced synchrotron and lab-based X-ray imaging techniques and electrochemical characterization to improve the PEWE cell performance at low Ir loadings using novel MPLs. For the first time, the 3D nanostructure of the catalyst layer was characterized under dry and wet conditions using ptychographic X-ray laminography. We prepared catalyst layers (CL) at three iridium loadings between 2.5 and 0.1 mg_Ircm⁻² in two different configurations: depositing either on the membrane or on the Ti-substrate (MPL). The MPL structure and catalyst distribution at its surface were analyzed using X-ray tomographic microscopy. Moreover, we investigated the effect of introducing a thin protective Pt coating on the MPL. The electrochemical performance was characterized for all cell combinations, and an in-depth kinetic analysis revealed information on CL utilization. The MPLs exhibit significant benefits for reducing iridium loadings, allowing performance to be sustained with only modest voltage losses. The challenges in fabricating anodic CLs with reduced catalyst loadings and the advantages of using an MPL in both configurations are discussed. The findings of this study contribute to accomplishing the required targets in terms of power-specific iridium loadings for future PEWE systems.