Hierarchical S-modified Cu porous nanoflakes for efficient CO2 electroreduction to formate

Silver-Doped Porous Copper Catalysts for Efficient Resource Utilization of CO-Containing Flue Gases

CO is both a key intermediate in the electrocatalytic conversion of CO2 and a valuable C1 resource, with the potential to reduce carbon emissions and mitigate the energy crisis. However, industrially emitted CO remains underutilized due to inefficiencies and economic challenges. Electrocatalytic CO reduction offers a promising approach for the efficient and environmentally friendly utilization of CO-containing flue gases. Nevertheless, current technologies face limitations, such as low operating currents and difficulties in adaptation to complex reaction gas components. Here, we report a low-cost silver-doped porous copper oxide (Ag-pCuO) catalyst. The doping of a moderate amount of Ag (0.875% doping) endows porous CuO with highly selective Cu-Ag active sites, enhanced CO adsorption, and improved surface valence stability, allowing Ag0.875%-pCuO to achieve remarkable catalytic performance in a carbon-doped titanium-based membrane electrode assembly electrolytic cell. It achieves a remarkable C2+ faradic efficiency of up to 94% at a high current density of -4 A under a simulated calcium carbide furnace gas atmosphere and demonstrates exceptional stability, with only a 6.08% decline in C2+ faradic efficiency after over 110 h of continuous operation. In summary, this research presents a novel approach for applying Ag-doped copper-based catalysts to industrially utilize CO-containing flue gases, especially from calcium carbide furnaces.

Graphene quantum dot-mediated anchoring of highly dispersed bismuth nanoparticles on porous graphene for enhanced electrocatalytic CO2 reduction to formate

The electrocatalytic reduction of CO2 to produce formic acid is gaining prominence as a critical technology in the pursuit of carbon neutrality. Nonetheless, it remains challenging to attain both substantial formic acid production and high stability across a wide voltage range, particularly when utilizing bismuth-based catalysts. Herein, we present a novel graphene quantum dot-mediated synthetic strategy to achieve the uniform deposition of highly dispersed bismuth nanoparticles on porous graphene. This innovative design achieves an elevated faradaic efficiency for formate of 87.0% at -1.11 V vs. RHE with high current density and long-term stability. When employing a flow cell, a maximum FEformate of 80.0% was attained with a total current density of 156.5 mA cm-2. The exceptional catalytic properties can be primarily attributed to the use of porous graphene as the support and the auxiliary contribution of graphene quantum dots, which enhance the dispersion of bismuth nanoparticles. This improved dispersion, in turn, has a significantly positive impact on CO2 activation and the generation of *HCOO intermediates to facilitate the formation of formate. This work presents a straightforward technique to create uniform metal nanoparticles on carbon materials for advancing various electrolytic applications.

Cu-based catalyst designs in CO2 electroreduction: precise modulation of reaction intermediates for high-value chemical generation

The massive emission of excess greenhouse gases (mainly CO2) have an irreversible impact on the Earth's ecology. Electrocatalytic CO2 reduction (ECR), a technique that utilizes renewable energy sources to create highly reduced chemicals (e.g. C2H4, C2H5OH), has attracted significant attention in the science community. Cu-based catalysts have emerged as promising candidates for ECR, particularly in producing multi-carbon products that hold substantial value in modern industries. The formation of multi-carbon products involves a range of transient intermediates, the behaviour of which critically influences the reaction pathway and product distribution. Consequently, achieving desirable products necessitates precise regulation of these intermediates. This review explores state-of-the-art designs of Cu-based catalysts, classified into three categories based on the different prospects of the intermediates' modulation: heteroatom doping, morphological structure engineering, and local catalytic environment engineering. These catalyst designs enable efficient multi-carbon generation in ECR by effectively modulating reaction intermediates.