EES catalysis最新文献

Aqueous redox flow batteries (AQRFBs) employing non-flammable electrolytes are recognized for their inherent safety and eco-friendliness, making them promising candidates for large-scale energy storage systems. Furthermore, the unique architecture of this battery technology enables autonomous decoupling of power and energy, resulting in higher capacity and enhanced cost-effectiveness compared to other battery technologies. Nonetheless, the limited electrochemical stability of water leads to water electrolysis during the electrochemical process, triggering undesired parasitic reactions, namely, the hydrogen evolution reaction, and ion-cross-over. These reactions significantly affect the electrochemical performance of the system, giving rise to several challenges, including low Coulombic efficiency and a short cycle life, hindering the advancement of AQRFBs. To overcome these obstacles and achieve high-potential AQRFBs, it becomes essential to incorporate a reaction-inhibitor to encounter water electrolysis during battery operation. This perspective review focuses on addressing and mitigating the thermodynamic limitations through improved strategies, proposing effective approaches to suppress aforementioned side reactions.

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The electrochemical carbon dioxide reduction reaction (CO₂RR) is a way to alleviate environmental pollution and realize carbon recycling, which converts CO₂ into value-added chemicals and fuels. Recently, the delocalization state regulation of catalysts has emerged as an effective method to evaluate the catalytic performance in CO₂RR. The delocalization state of catalysts has been found to promote the stability and selectivity of CO₂RR, which is essentially based on enhancing the electron conductivity of catalysts or regulating the adsorption of intermediates. In this mini-review, we first discuss how the delocalization state of catalysts affects their catalytic properties. Then, we summarize recent progress on the subject in two parts: stability and selectivity of CO₂RR. In particular, we have emphasized the selectivity part, breaking it into two components: hydrogen adsorption and CO₂RR intermediates. Finally, we conclude the review with some observations by outlining the challenges and presenting our viewpoints on the future research directions in this field.

Single-atom catalysts (SACs) exhibit maximized atomic utilization with individual metal atoms anchored on supporting materials, where the pursuit of high performance and low cost presents challenges. In this case, carbon provides structural versatility and customizable properties as a supporting material, which has been extensively studied. Biomass materials have emerged as promising precursors for the preparation of carbon-based SACs due to their renewable nature for sustainability, abundance for low cost, and high carbon content for advanced performance. In this review, representative synthesis strategies and advanced characterization techniques for biomass-derived CS-SACs are summarized, which facilitate the establishment of guidelines for the rational design and fabrication of biomass-derived SACs. In addition, we provide a timely and comprehensive discussion on the use of a broad range of natural biomass for SACs, with insights into the specific carbon nature of biomass resources, including their carbon structures, metal-carbon coordination environment, and center metal species. Furthermore, the application areas of biomass-derived CS-SACs in various catalytic processes are reviewed. Overall, the challenges and future perspectives of using biomass as precursors for SACs are outlined. We hope that this review can offer a valuable overview of the current knowledge, recent progress, and directions of biomass-derived SACs.

The global aviation industry is under increasing pressure to mitigate its environmental impact and achieve net-zero objectives. Reducing CO₂ emissions alone is insufficient, as it overlooks crucial parts of the overall climate impacts. Addressing climate-neutral aviation fuel production from sustainable feedstock and effective technology is crucial. Here, we present a breakthrough in sustainable upgrading of pyrolysis oil with CH₄ to jet fuel using non-thermal plasma triphase catalysis, characterized by an opposite gas–liquid flow and a fluidized catalyst under near-ambient conditions of atmospheric pressure and around 100 °C, resulting in an impressive liquid oil yield of almost 87%. This work delves into the strategic distribution of iridium (Ir) as minute nanoclusters on GaN, which serves to ensure robust catalytic stability and instigate synergistic interactions between plasma and catalysis. This unique configuration establishes an active surface conducive to the transformation of pyrolysis oil into essential jet fuel constituents, encompassing gasoline hydrocarbons (C₅–C₁₁), aromatics, and cycloalkanes. Both empirical experiments and computational analysis converge to confirm that methane activation can effectively occur within the plasma zone while surface reactions of cleavage of C–H, C–O, and C–N bonds with adsorbed H and CH_x active species occurring on the Ir(100) surface play a crucial role in enhancing selectivity, resulting in upgraded oil meeting jet fuel commercial specifications. This novel approach holds substantial promise in the pursuit of sustainable and eco-friendly jet fuel production.

Spinel NiCo₂O₄ are excellent catalysts for complete methane oxidation. Nevertheless, the spinel structure is thermally unstable and its activity is negatively affected by humidity. Herein, we report crystal facet engineering synthesis of spinel NiCo₂O₄ hexagonal nanosheets with different exposed facets. Density functional theory (DFT) simulations predict that a more viable reaction mechanism for methane oxidation occurs on 112-NiCo₂O₄ with {112} exposed facets compared with 111-NiCo₂O₄ with {111} exposed facets. Detailed material characterization and catalytic oxidation testing verified the DFT results showing that 112-NiCo₂O₄ has better thermal stability as well as higher catalytic activity towards methane oxidation than 111-NiCo₂O₄. Conversely, 111-NiCo₂O₄ has the enhanced water resistance of the two catalysts. DFT calculations suggest that OH groups tend to preferentially adsorb onto metal sites, which (1) reduces the number of active sites available and (2) makes CH₄ adsorption and activation a more arduous process. This study offers insights on the behavior of spinel oxide catalysts towards methane combustion in dry and humid conditions, further demonstrating that crystal facet engineering can be a practical strategy to tune the activity and water resistance of metal-oxide catalysts.

Enhancing the activity and durability of Pt nanoparticles for the oxygen reduction reaction (ORR) is of critical importance in achieving an optimal, cost-efficient proton exchange membrane fuel cell (PEMFC) catalyst. Aimed at improving the intrinsic catalytic activity and durability of the Pt nanoparticles, this work utilizes a library of fourteen 3d, 4d, 5d, and f metal atomically dispersed metal–nitrogen–carbon (M–N–C) catalysts as active supports, synthesizing a corresponding library of Pt/M–N–C catalysts. XPS and XANES measurements indicate a reduced oxidation state of the Pt nanoparticles due to interactions with the M–N–C support. Further alteration of the electronic structure of the Pt nanoparticles arising from interactions with the M–N_x sites is evidenced through the CO oxidation peak, which experiences broadening, shoulder formation and peak shifting over varying M–N–C supports. ORR performance reveals the significantly enhanced intrinsic catalytic activity of the Pt nanoparticles on M–N–Cs over a Pt/C standard, through specific activity calculations. This work demonstrates the application of highly active hybrid Pt/M–N–C catalysts, showcasing the variation in activity as one traverses the periodic table, while highlighting important design criteria to achieve highly active and durable ORR catalysts.

The chemical manufacturing of commodity chemicals, responsible for approximately 24% of global carbon emissions, poses a critical environmental challenge. With escalating demand due to economic development, urgent decarbonization strategies are imperative. Traditional electrochemical synthesis encounters hindrances, especially mass transfer limitations at relevant current densities, primarily attributed to gas phase reactants and products. In this Perspective, we explore the viability of high-pressure electrochemistry as a transformative solution. Our analysis reveals that applying pressure can overcome mass transfer limitations, enhance selectivity, and improve overall activity, all while minimizing energy consumption and capital expenditure for distributed production processes. We shed light on the influence of pressure on Pourbaix diagrams, electric double layer, electrolyte activity, conductivity, electrostriction-enhanced selectivities, catalyst activity, and stability. Additionally, insights are provided into the design and operation of existing reactors and tools for high-pressure electrochemistry, along with the imperative for future fundamental studies. In the context of decentralized production, we argue that the marginal differential capital costs associated with high-pressure reactors become inconsequential. Ultimately, our work seeks to pave the way for the decarbonization of the chemical industry by establishing innovative pathways for the electrochemical synthesis of commodity chemicals, presenting high-pressure electrochemical synthesis as a potential paradigm shift in this transformative journey.

Structurally ordered intermetallic noble metal nanocrystals (NCs) with unconventional phases exhibit impressive catalytic activity and stability resulting from the novel atomic stacking patterns and coordination environments, and thus have attracted extensive attention for energy-conversion electrocatalysis in recent years. In this mini-review, recent advances in developing unconventional intermetallic noble metal NCs for high-performance electrochemical energy conversion technologies are highlighted. First, the theoretical aspects of the relationship between the crystal phases of metal alloys and their electrocatalytic performance are introduced, and the obstacles in the preparation of unconventional intermetallic noble metal NCs are described. Then, several representative examples are presented to highlight the applications of unconventional noble metal-based intermetallic NCs as electrocatalysts for different electrocatalytic reactions. Finally, perspectives and future opportunities for the rational design and preparation of unconventional intermetallic NCs for sustainable electrochemical devices are discussed.

Electrochemical CO₂ reduction is a topic of major interest in contemporary research as an approach to use renewably-derived electricity to synthesise useful hydrocarbons from waste CO₂. Various strategies have been developed to optimise this challenging reaction at electrode interfaces, but to-date, decoupled electrolysis has not been demonstrated for the reduction of CO₂. Decoupled electrolysis aims to use electrochemically-derived charged redox mediators – electrical charge and potential vectors – to separate catalytic product formation from the electrode surface. Utilising an electrochemically generated highly reducing redox mediator; chromium propanediamine tetraacetate, we report the first successful application of decoupled electrolysis to electrochemical CO₂ reduction. A study of metals and metal composites found formate to be the most accessible product, with bismuth metal giving the highest selectivity. Copper, tin, gold, nickel and molybdenum carbide heterogeneous catalysts were also investigated, in which cases H₂ was found to be the major product, with minor yields of two-electron CO₂ reduction products. Subsequent optimisation of the bismuth catalyst achieved a high formate selectivity of 85%. This method represents a radical new approach to CO₂ electrolysis, which may be coupled directly with renewable energy storage technology and green electricity.