Coordination environment tuning of nickel sites by oxyanions to optimize methanol electro-oxidation activity

To achieve zero-carbon economy, advanced anode catalysts are desirable for hydrogen production and biomass upgrading powered by renewable energy. Ni-based non-precious electrocatalysts are considered as potential candidates because of intrinsic redox attributes, but in-depth understanding and rational design of Ni site coordination still remain challenging. Here, we perform anodic electrochemical oxidation of Ni-metalloids (NiPx, NiSx, and NiSex) to in-situ construct different oxyanion-coordinated amorphous nickel oxyhydroxides (NiOOH-TOx), among which NiOOH-POx shows optimal local coordination environment and boosts electrocatalytic activity of Ni sites towards selective oxidation of methanol to formate. Experiments and theoretical results demonstrate that NiOOH-POx possesses improved adsorption of OH* and methanol, and favors the formation of CH3O* intermediates. The coordinated phosphate oxyanions effectively tailor the d band center of Ni sites and increases Ni-O covalency, promoting the catalytic activity. This study provides additional insights into modulation of active-center coordination environment via oxyanions for organic molecules transformation. Coordination environments around metal sites are important in electrocatalysis. Here, Ni metalloid oxidation produces oxyanion doped amorphous Ni-oxyhydroxides where substitution with phosphorus is found to boost methanol electrooxidation activity.

Automated summary

To achieve a zero-carbon economy, advanced anode catalysts are needed for hydrogen production and biomass upgrading using renewable energy. This study focuses on the electrochemical oxidation of nickel-metalloids to create oxyanion-coordinated amorphous nickel oxyhydroxides. The results show that substitution with phosphorus enhances the electrooxidation activity of methanol.