Pt doped NiCo2O4 electrolysis for achieving highly efficient overall water splitting in alkaline condition

Abstract

The development of efficient electrocatalysts to substitute Pt and Ir in overall water splitting is critical for advancing sustainable hydrogen generation. Transition metal oxides have attracted wide attention and shown promising catalytic activity in water splitting reaction. In this work, the doped bimetallic oxide Pt-NiCo₂O₄ catalyst having urchin-like structure surrounding with abundant nanoneedles is prepared by multi-step hydrothermal reaction, ion-exchange method and annealing process. In alkaline electrolyte (1.0 M KOH), the prepared electrocatalyst requires remarkably low overpotentials of 40 mV for hydrogen evolution reaction and 263 mV for oxygen evolution reaction at 10 mA cm⁻². The assembled two-electrode alkaline electrolyzer achieves a current density of 10 mA cm⁻² at a low cell voltage of 1.62 V, rivaling the performance of commercial electrodes. The unique urchin-like structure not only facilitates the gas emission, but also creates abundant active sites, which promote electron transfer and improve reaction kinetics. Furthermore, computational modeling reveals that optimized d-band center and energy barrier of H₂O decomposition after Pt atoms doping. This work establishes a rational strategy for designing high-efficiency bifunctional electrocatalysts in overall water splitting under alkaline conditions.