Heterogeneous bimetallic oxides/phosphides nanorod with upshifted d band center for efficient overall water splitting

Electrocatalytic water splitting is the most directly available route to generate renewable and sustainable hydrogen. Here, we report the design of a composite material in which arrays of square pillar-like NiMoO4 nanorods coated with N, P-doped carbon layers are uniformly contained in numerous nested nanoparticle structures. The catalysts have superior catalytic activity, requiring only 59 mV and 187 mV for HER and OER to attain a current density of 10 mA/cm2, respectively. The assembled two-electrode electrolytic cell required a voltage of 1.48 V to reach 10 mA/cm2, along with excellent long-term stability. Theoretical calculations reveal that electrons aggregate and redistribute at the heterogeneous interface, with the d-band centers of the Ni and Fe atoms being positively shifted compared to the Fermi level, effectively optimizing the adsorption of intermediates and reducing the Gibbs free energy, thus accelerating the catalytic process. Meanwhile, an integrated solar-driven water-splitting system demonstrated a high and stable solar-to-hydrogen efficiency of 18.20%. This work provides new possibilities for developing non-precious metal-based bifunctional electrocatalysts for large-scale water splitting applications.