Versatile Mo modulation effects enable efficient electrocatalytic aqueous methanol electro-reforming over surface-engineered NiCoMo alloy

Electro-reforming of methanol under ambient conditions is considered as an attractive strategy for energyefficient hydrogen production. Developing high-performance and cost-effective electrocatalysts is indispensable for boosting the electro-reforming reaction. Herein, a NiCoMo alloy pre-catalyst featured by nanosheets covered nanowires arrays is proposed. The NiCoMo pre-catalyst undergoes surface reconstruction along with Mo leaching during the anodic cyclic voltammetry (CV) stabilization process, forming a Mo substituted NiCoOOH layer as a real catalyst. In contrast, the surface structure of NiCoMo almost remains unchanged after cathodic CV stabilization. The surface engineered catalysts are highly active, and thus the corresponding two-electrode cell for methanol electro-reforming delivers 50 mA cm-2 at 1.46 V with high stability over 50 h. The Faradaic efficiency of hydrogen and formate generation maintains above 98 % and 85 % respectively after 50 h of coelectrolysis. Experimental and theoretical results 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.

Automated summary

Developing high-performance electrocatalysts is crucial for efficient methanol electro-reforming. In this study, a NiCoMo alloy pre-catalyst with nanosheets covered nanowires arrays is proposed, which undergoes surface reconstruction and forms a Mo substituted NiCoOOH layer as the real catalyst. The surface engineered catalysts exhibit high activity and stability, achieving efficient co-production of hydrogen and formate. The incorporation of Mo plays multiple roles in stabilizing the structure, promoting surface reconstruction, modulating electronic structure, and boosting catalytic activity.