Multi-Center Cooperativity Enables Facile C-C Coupling in Electrochemical CO2 Reduction on a Ni2P Catalyst

The increasing interest for renewable electricity-driven CO2 electroreduction calls for effective strategies in catalyst design, which have so far mainly focused on the compositional modulation such as doping and alloying. Recently, attention has turned to the microstructural tailoring of catalytic centers with a multi-center architecture to promote the formation of multi-carbon products, but theoretical understanding lags far behind the experimental discoveries. Herein, a systematic first principles study is performed on the representative electrocatalyst, Ni2P, which is characterized by densely distributed Ni3 catalytic centers and displays high selectivity to C-C coupling during CO2 reduction reaction (CO2RR). Not only the Ni atoms in each trinuclear Ni3 site can cooperatively accommodate reaction intermediates for better opportunities of their coupling, but the adjacent Ni3 sites can also work in synergy to drive the highly endothermic hydrogenation steps in forming critical multi-carbon species. At the core of this capability lies the participation of the hydrogen-bonding network of water in transferring surface protons between neighboring Ni3 sites, which builds a kinetically feasible path to circumvent the thermodynamic penalty in an electrochemical step. This work uncovers the mechanism by which cooperativity arises in multi-center microstructures, with implications generally for the design of CO2RR electrocatalysts to obtain valuable chemicals.