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

Electrochemical reduction of CO2 and H2O to synthesize gas (H2 and CO mixture) is of significant interest due to established industrial pathways to tune the H2 to CO composition to generate an array of valuable products including methanol, synthetic fuel, synthetic natural gas, and hydrogen. However, controlled H2: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 θw ranging from 47° and 135°, H2: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 (θw = 47°) and more hydrophobic (θw = 135°) samples showed an increasing H2:CO trend with rising potentials (0.7–1.2 V versus RHE) due to mass transport. Conversely, silver electrocatalyst with θw = 110° exhibited a constant H2:CO ratio of 4. This indicates catalyst wettability potentially affects *H and *HOCO intermediates’ adsorption, impacting H2: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.