EES catalysis最新文献

Electrochemical CO₂ reduction offers a promising method of converting renewable electrical energy into valuable hydrocarbon compounds vital to hard-to-abate sectors. Significant progress has been made on the lab scale, but scale-up demonstrations remain limited. Because of the low energy efficiency of CO₂ reduction, we suspect that significant thermal gradients may develop in industrially relevant dimensions. We describe here a model prediction for non-isothermal behavior beyond the typical 1D models to illustrate the severity of heating at larger scales. We develop a 2D model for two membrane electrode assembly (MEA) CO₂ electrolyzers; a liquid anolyte fed MEA (exchange MEA) and a fully gas fed configuration (full MEA). Our results indicate that full MEA configurations exhibit very poor electrochemical performance at moderately larger scales due to non-isothermal effects. Heating results in severe membrane dehydration, which induces large Ohmic losses in the membrane, resulting in a sharp decline in the current density along the flow direction. In contrast, the anolyte employed in the exchange MEA configuration is effective in preventing large thermal gradients. Membrane dehydration is not a problem for the exchange MEA configuration, leading to a nearly constant current density over the entire length of the modeled domain, and indicating that exchange MEA configurations are well suited for scale-up. Our results additionally indicate that a balance between faster kinetics, higher ionic conductivity, smaller pH gradients and lower CO₂ solubility causes an optimum operating temperature between 60 and 70 °C.

Welcome to the first issue of EES Catalysis in 2025! As we enter this new year, we reflect on the remarkable journey since our launch in 2023. With a strong year in 2024, EES Catalysis has grown into a dynamic platform for groundbreaking research and a thriving community dedicated to advancing energy and environmental catalysis. In this Editorial, we are excited to highlight recent achievements and share our vision for the promising future of EES Catalysis.

Clean hydrogen production using renewable solar energy is an important aspect in the development of a sustainable society. The premise of developing highly efficient photocatalysts for hydrogen production relies on achieving smooth charge carrier kinetics with efficient visible light absorption. Constructing isotype heterojunctions with structural or compositional similarity can enhance charge carrier separation at the interface, leading to improved utilization of light energy. However, this approach is often constrained by the availability as well as intrinsic properties of monomers. Herein, carbon facilitated in situ fabrication of an isotype heterojunction based on a poly(heptazine imide) (PHI) structure with high crystallinity and extended π-conjugation was proposed by calcinating carbon-modified melon in the “semi-liquid” NaCl/KCl salt. The heterojunction effect induced by the visible light responsive Na–PHI and K–PHI, as well as the strong charge coupling between heptazine and carbon ring in the covalent interface forms multi-directional built-in electric field and effectively promotes the separation of charge carriers. Together with the visible light absorption extension by simultaneous carbon ring decoration, C@Na–PHI/K–PHI shows superior photocatalytic hydrogen evolution activities under visible light irradiation and the apparent quantum efficiencies reach 29.3% and 3% under 420 and 550 nm, respectively. This study pioneers the idea and provides a useful reference for the design of PHI isotype heterojunctions for the effective utilization of solar energy.

Membrane-less electrolysis is utilized for many gaseous chemical productions. However, the problems of gas mixing and low energy efficiency remain huge obstacles for its practical application. Herein, we have prepared a biomimetic electrode by three-dimensional (3D) printing technology, featuring a “slippery aerophobic” surface and micro-cone array structure with tunable tilting angles. These electrodes enable the bubbles that are generated at the cone tip to “roll-up” rapidly along the electrode towards its base, rather than being directly released into the electrolyte, resulting in gas mixing. The unidirectional bubble transportation behavior was understood by a collective analysis of the Laplace pressure on cones, bubble buoyancy and irreversible hysteresis. As a proof of concept, we employed this biomimetic electrode in membrane-less water electrolysis. At a current density of 240 mA cm⁻², we achieved the separation of H₂ and O₂ gases with >99.99% purity even with an electrode distance as short as 1.5 mm. This work demonstrated the efficiency of precisely manipulating bubble transportation in membrane-less electrolysis that does not rely on expensive membranes.

Proton exchange membrane fuel cells (PEMFCs) offer energy solutions of high efficiency and low environmental impact. However, the sluggish kinetics of the oxygen reduction reaction (ORR) at the cathode limit their commercialization. Pt-based electrocatalysts, particularly octahedral (oh)PtNi bimetallic catalysts doped with additional transition metals, stand out as promising candidates for enhancing ORR rates and overall cell performance. A key challenge in the development and validation of active oh PtNi electrocatalysts is the unsuccessful translation of laboratory-scale catalyst test results, typically assessed using the rotating disk electrode (RDE) method, to practical applications in membrane electrode assembly (MEA) for PEMFCs. Here, we consider a new family of Ir-doped octahedral ORR fuel cell catalysts with very high RDE-based Pt mass activities. First, we designed the catalysts and tuned the catalyst layer properties to achieve the new state-of-the-art performance for oh-PtNi catalysts in PEMFCs. Still, a significant decrease in relative performance with respect to Pt/C when transitioning from RDE into an MEA-based cathode environment was observed. Thus, to better understand this performance loss, we investigated the effects of ionomer–catalyst interactions by adjusting the I/C ratio, the effect of temperature by applying RDE under high temperature, and the effects of acidity and high current density by applying and introducing the floating electrode technique (FET) to shaped nanoalloys. A severe detrimental effect was observed for high I/C ratios, with a behaviour contrasting reference commercial catalysts, while the negative effect of high temperatures was enhanced at low I/C. Based on this analysis, our study not only demonstrates a catalyst with enhanced ORR activity and specifically higher electrochemical surface area (ECSA) among oh-PtNi catalysts, but also provides valuable insights into overcoming MEA implementation challenges for these advanced fuel cell catalysts.

The electrochemical N₂ reduction reaction (eNRR) is a promising pathway for clean and sustainable production of ammonia, a compound essential for global industry. The challenges of the eNRR lie in the complexity of the electrode–electrolyte interface (EEI). While advances have been made in tuning the electrolyte compositions, the understanding of underlying atomic-level mechanisms remains limited. Operando computational techniques are emerging as instrumental tools to address relevant issues. In this review, we highlight a path forward by summarizing the recent advances in engineering strategies for direct-eNRR, including cations, organic solvents, ionic liquids; and for indirect-NRR with the incorporation of lithium-mediators. Additionally, we summarized relevant computational techniques that can investigate the interfacial dynamic properties associated with electrolyte modifications within N₂ reduction. By promoting the application of these computational methodologies, this review contributes to the ongoing efforts towards the realization of highly efficient electrochemical N₂ reduction.

The sustainable electrocatalytic reduction of carbon dioxide into solar fuels offers a potential pathway to mitigate the impact of greenhouse gas-induced climate change. Here, we successfully achieved a high solar-to-fuel (STF) efficiency of 11.5% by integrating a low-cost tandem solar cell with robust, high-performance, non-precious metal-based electrocatalysts. The bismuth-based cathode exhibited a high formic acid selectivity of 97.2% at a potential of −1.1 V_RHE, along with an outstanding partial current density of 32.5 mA cm⁻². Furthermore, upon undergoing more than 24 hours of electrolysis, we observed an enhancement in the catalytic activity. Through comprehensive analysis including in situ Raman spectroscopy and density functional theory (DFT) calculations, we elucidated that the in situ transformation of bismuth into bismuth subcarbonate (BOC) induces multiple effects: (i) the formation of grain boundaries between phases with distinct lattice parameters, (ii) electronic modulation due to defect formation, and (iii) changes in the binding modes of key reaction intermediates on active sites, resulting in the stabilization of *OCHO species. The cause of these phase transformations was attributed to the structural similarity between the cathode template and BOC. The sustainability of the STF efficiency sets a new benchmark for all cost-effective photovoltaic-coupled electrochemical systems.

The electrocatalytic hydrogen evolution reaction (HER) is an efficient technology for hydrogen production and holds great significance for the development of renewable energy economies. Rare-metal-based catalysts are considered benchmark catalysts for the HER; however, their application in HER reactors is limited due to their high cost and poor stability. Rare-metal single atom catalysts (RMSACs) can be considered as promising candidates for the HER due to several advantages such as high activity, high stability, and high atom utilization. The rational design of RMSACs for HER reactors has become a research hotspot in this field. This paper reviews the research progress in the development of RMSACs for large scale hydrogen production under actual operating conditions, including high current density, seawater electrolysis, and long-term operation. Firstly, the mechanism, design and synthesis method of RMSACs for the HER are summarized. Then the atomic-level rational design strategy of RMSACs was proposed for enhancing the HER performance under actual operating conditions. Lastly, the opportunities and challenges for industrial applications of RMSACs are also discussed.

Methanol (CH₃OH) synthesis from carbon dioxide (CO₂) hydrogenation is an industrially viable approach to CO₂ utilization. For the recently developed indium oxide (In₂O₃) catalyst, higher performance may be achieved by introducing transition metal promoters, although recent studies suggest that single atom sites favour CO formation. Here, by density functional theory-based microkinetic simulations, bulk-doped Pt/In₂O₃ single atom catalysts (SACs) with much higher CO₂ reactivity than the In₂O₃ catalyst while maintaining CH₃OH selectivity were designed. Several Pt/In₂O₃ SACs were synthesized to confirm our theoretical predictions. The synthesized Pt/In₂O₃ SAC in the predominantly bulk-doped form exhibits much higher CO₂ reactivity than the In₂O₃ catalyst with high stability and similar CH₃OH selectivity, yielding a CH₃OH productivity of 1.25 g g_cat⁻¹ h⁻¹. This study demonstrates the power of computational methods in designing oxide-based catalysts for industrial reactions and reveals a bulk-doped SAC with high performance.

Phasing out petrochemical-based thermoplastics with bio-plastics produced in an energy efficient and environmentally friendly way is of paramount interest. Among them, polylactic acid (PLA) is the flagship with its production accounting for 19% of the entire bioplastics industry. Glycerol electrolysis for producing the monomer lactic acid, while co-generating green H₂, represents a promising approach to boost the production of PLA, yet the reaction selectivity has been a bottleneck. Here, we report a combined electrochemical and chemical route using a tandem Pt/C-γ-Al₂O₃ multicomponent catalyst which can achieve a glycerol-to-lactic acid selectivity of 61.3 ± 1.2%, among the highest performance reported so far. Combining an experimental and computational mechanistic analysis, we suggest that tuning the acidic sites on the catalyst surface is crucial for shifting the reaction towards the dehydration pathway, occurring via dihydroxyacetone intermediate. Within the tandem effect, Pt is the active site to electrochemically catalyze glycerol to dihydroxyacetone and glyceraldehyde, while the γ-Al₂O₃ provides the required acidic sites for catalyzing dihydroxyacetone to the pyruvaldehyde intermediate, which will then go through Cannizzaro rearrangement, catalyzed by the OH⁻ ions to form lactic acid. This catalytic synergy improves the selectivity towards lactic acid by nearly two-fold. A selectivity descriptor (ΔG_GLAD* − ΔG_DHA*) from density functional theory calculations was identified, which could be used to screen other materials in further research. Our findings highlight the promise of tandem electrolysis in the development of strategies for selective electrochemical production of high-value commodity chemicals from low value (waste) precursors.