Nanoporous AgCuAuMo Nanobelt-Like Ligaments with Large Surface Area and Current Density for CO₂ Electroreduction

CO₂ electroreduction catalyst with a broad potential range and high selectivity is important for ensuring consistent efficiency and reliability in renewable energy integration into electrocatalytic processes. In this study, we find that the addition of different the fourth elements would have different effects on the ternary AgCuAu nanoporous alloy catalyst, which is an optimized catalyst in our previous work. The addition of Mo exhibits the lightest negative effect on the intrinsic activity of AgCuAu due to the highest electronegativity of Mo among these doping elements (Mo, Ni, Ti, and Ce). Interestingly, the Mo addition in the Al₂AgCuAu-based precursor alloy results in nanoporous AgCuAuMo with thin nanobelt-like ligaments and greatly enhanced specific surface area, probably due to the low surface diffusion rate of Mo and its direction-selected passivation during the dealloying. As a result, the nanoporous multicomponent AgCuAuMo alloy (NP-Ag₃Cu₃Au₃Mo_0.5) achieves a Faradaic efficiency (FE) for CO of more than 90% over a wide potential window of ∼1.0 V, peaking at 95.7% at −0.973 V versus the reversible hydrogen electrode (RHE). A CO partial current density (j_CO) of 202 mA/cm² can be achieved at −1.373 V vs RHE.