Monolithic-structured nickel silicide electrocatalyst for bifunctionally efficient overall water splitting

The rational design and synthesis of cost-effective and efficient bifunctional electrocatalysts are crucial for developing hydrogen energy yet challenging. Here we report porous monolith electrocatalysts (PMECs) comprising transition metal silicide (e.g., nickel silicide) with high activity and durability. These PMECs offer strong synergetic effects and high exposure of active sites, resulting in excellent kinetics in catalyzing both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), which surpass the benchmark catalysts RuO2 and Pt/C. The doping strategy is demonstrated to further enhance electrocatalytic performance by constructing Mo-doped Ni2Si PMEC, which requires only a cell voltage of 1.60 V at 100 mA cm-2. Density functional theory calculations display that the synergistic effect of Ni and Si can reduce the energy barriers of intermediate adsorption, and the introduction of Mo into Ni2Si can further decrease the energy barrier of determining step and optimize the H* adsorption energy, thus enhancing the electrochemical kinetics for OER and HER. Our work paves the way for designing high-efficiency and low-cost porous monolith catalysts through a facile and scalable method, showing great prospects for industrialization.