Catalytic conversion of captured CO2 into chemicals and fuels is an appealing route for manufacturing sustainable, carbon-neutral products. Direct conversion of CO2 into liquid chemicals is especially attractive because it has practical advantages associated with easier storage and transport. Formic acid (formate) is one candidate that has current agricultural and industrial uses, and it is also an emerging liquid hydrogen carrier. SnO2 is the state-of-the-art catalyst for electrochemically converting CO2 into formate, but it often suffers from low reaction rates and particle agglomeration during electrolysis. This talk describes our recent efforts in designing three-dimensionally nanostructured SnO2 catalysts for electrocatalytic conversion of CO2 into formate. We developed a polymer templating strategy to synthesize hollow, ~200 nm diameter spheres constructed from ~10 nm crystalline SnO2 nanoparticles. The spherical SnO2 catalysts demonstrated formate Faradaic efficiencies of 70-80% between -0.9 V to -1.3 V vs. the reversible hydrogen electrode (RHE) with a maximum formate partial current density exceeding 70 mAformate/cm2geo at -1.3V vs. RHE in an aqueous H-Cell. These values represent a 7-fold improvement over commercially-available SnO2 nanoparticles and a 2-fold improvement over non-structured SnO2 nanoparticles synthesized without a polymer template. We attribute these performance enhancements to increased electrochemical surface area of the SnO2 spheres. Long-term stability was demonstrated during a 36-hour electrolysis at -1.2V vs. RHE with a stable formate partial current density and lack of particle agglomeration. These results demonstrate that rational control of 3D structure can improve current density and catalyst stability for electrochemical reduction of CO2 into more useful chemicals.

Electrochemically converting CO2 to formate at three-dimensionally structured Tin nanocatalysts

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.