Enhanced efficiency for carbon dioxide electroreduction to formate by electrodeposition Sn on Cu nanowires

Multi-metallic Layered Catalysts for Stable Electrochemical CO2 Reduction to Formate and Formic Acid

Electrochemical CO2 reduction (ECR) to value-added products such as formate/formic acid is a promising approach for CO2 mitigation. Practical ECR requires long-term stability at industrially relevant reduction rates, which is challenging due to the rapid degradation of most catalysts at high current densities. Herein, we report the development of a bismuth (Bi) gas diffusion electrode on a polytetrafluoroethylene-based electrically conductive silver (Ag) substrate (Ag@Bi), which exhibits high Faradaic efficiency (FE) for formate of over 90 % in 1 M KOH and 1 M KHCO3 electrolytes. The catalyst also shows high selectivity of formic acid above 85 % in 1 M NaCl catholyte, which has a bulk pH of 2-3 during ECR, at current densities up to 300 mA cm-2. In 1 M KHCO3 condition, Ag@Bi maintains formate FE above 90 % for at least 500 hours at the current density of 100 mA cm-2. We found that the Ag@Bi catalyst degrades over time due to the leaching of Bi in the NaCl catholyte. To overcome this challenge, we deposited a layer of Ag nanoparticles on the surface of Ag@Bi to form a multi-layer Ag@Bi/Ag catalyst. This designed catalyst exhibits 300 hours of stability with FE for formic acid ≥70 % at 100 mA cm-2. Our work establishes a new strategy for achieving the operational longevity of ECR under wide pH conditions, which is critical for practical applications.

Nanostructure Engineering of Sn-Based Catalysts for Efficient Electrochemical CO2 Reduction

Excessive anthropogenic CO₂ emission has caused a series of ecological and environmental issues, which threatens mankind's sustainable development. Mimicking the natural photosynthesis process (i.e., artificial photosynthesis) by electrochemically converting CO₂ into value-added products is a promising way to alleviate CO₂ emission and relieve the dependence on fossil fuels. Recently, Sn-based catalysts have attracted increasing research attentions due to the merits of low price, abundance, non-toxicity, and environmental benignancy. In this review, the paradigm of nanostructure engineering for efficient electrochemical CO₂ reduction (ECO₂ R) on Sn-based catalysts is systematically summarized. First, the nanostructure engineering of size, composition, atomic structure, morphology, defect, surficial modification, catalyst/substrate interface, and single-atom structure, are systematically discussed. The influence of nanostructure engineering on the electronic structure and adsorption property of intermediates, as well as the performance of Sn-based catalysts for ECO₂ R are highlighted. Second, the potential chemical state changes and the role of surface hydroxides on Sn-based catalysts during ECO₂ R are introduced. Third, the challenges and opportunities of Sn-based catalysts for ECO₂ R are proposed. It is expected that this review inspires the further development of highly efficient Sn-based catalysts, meanwhile offer protocols for the investigation of Sn-based catalysts.