Microstructural origin of locally enhanced CO2 electroreduction activity on gold

Understanding how the bulk structure of a material affects catalysis on its surface is critical to the development of actionable catalyst design principles. Bulk defects have been shown to affect electrocatalytic materials that are important for energy conversion systems, but the structural origins of these effects have not been fully elucidated. Here we use a combination of high-resolution scanning electrochemical cell microscopy and electron backscatter diffraction to visualize the potential-dependent electrocatalytic carbon dioxide $$({\mathrm{C}}{\mathrm{O}}_{2})$$ electroreduction and hydrogen $$({{\mathrm{H}}_{2}})$$ evolution activity on Au electrodes and probe the effects of bulk defects. Comparing colocated activity maps and videos to the underlying microstructure and lattice deformation supports a model in which CO2 electroreduction is selectively enhanced by surface-terminating dislocations, which can accumulate at grain boundaries and slip bands. Our results suggest that the deliberate introduction of dislocations into materials is a promising strategy for improving catalytic properties. Although bulk defects can influence the performance of electrocatalysts used for energy conversion, their structural origins are still unclear. The effects of bulk defects on CO2 electroreduction and H2 evolution activity on Au electrodes are now elucidated.