Fine-tuning syngas composition using laser surface modified silver electrode for CO2 electroreduction

Electrochemical reduction of CO2 and H2O to synthesize gas (H-2 and CO mixture) is of significant interest due to established industrial pathways to tune the H-2 to CO composition to generate an array of valuable products including methanol, synthetic fuel, synthetic natural gas, and hydrogen. However, controlled H-2:CO ratios are challenging on CO-active electrocatalysts like silver. We demonstrate that applying laser engineering to adjust the surface wetting state of a silver electrocatalyst with water contact angles theta(w) ranging from 47 degrees and 135 degrees, H-2:CO ratios can be tuned from 1 to 4 at modest potentials (-0.7 V versus RHE, RHE-reversible hydrogen electrode) with almost total unity Faradaic efficiency. Both hydrophilic (theta(w) = 47 degrees) and more hydrophobic (theta(w) = 135 degrees) samples showed an increasing H-2:CO trend with rising potentials (0.7-1.2 V versus RHE) due to mass transport. Conversely, silver electrocatalyst with theta(w) = 110 degrees exhibited a constant H-2:CO ratio of 4. This indicates catalyst wettability potentially affects *H and *HOCO intermediates' adsorption, impacting H-2:CO ratios. Our results show the feasibility of syngas composition control on silver catalysts via surface wettability, providing a simpler alternative to complex multicomponent electrocatalytic systems.