Efficient Co-Production of Hydrogen and Value-Added Formate Over Bifunctional Nicomo Alloy Electrocatalyst with Nanosheet/Nanotube Architecture and Versatile Mo Modulation

Electrocatalytic hydrogen evolution reaction (HER) integrated with methanol upgrading reaction (MUR) is recently considered as a promising strategy for efficient hydrogen production. Developing high-performance and cost-effective electrocatalysts is indispensable for boosting these reactions. Herein, a NiCoMo alloy pre-catalyst featured by dense nanosheets covered tubular arrays is proposed. The NiCoMo pre-catalyst undergoes surface reconstruction along with Mo leaching during the anodic cyclic voltammetry (CV) stabilization process, forming a Co/Mo substituted NiOOH layer as a real catalyst. In contrast, the surface structure of NiCoMo almost remains unchanged after cathodic CV stabilization. The anodic and cathodic stabilized catalysts show low reaction potentials of 1.34 and -0.125 V at 50 mA cm -2 for MUR and HER, respectively. The two-electrode cell for methanol-water co-electrolysis delivers 50 mA cm -2 at 1.46 V with high stability over 50 h and achieves Faradaic efficiency of nearly 100% at both anode and cathode. Experimental observations and density functional theory calculations reveal that the Mo incorporation is of great importance for achieving efficient co-production of hydrogen and value-added formate, serving as structural stabilizing agent, surface reconstruction promoter, electronic structure modulator, and catalytic activity booster.