Crystalline/amorphous Co3(PO4)2–MoO3−x/NF heterojunction synergistically improves overall water-splitting kinetics

Abstract

Designing and constructing highly efficient, cost-effective, and durable non-precious metal bifunctional catalysts remains a challenge. In this work, by constructing crystalline/amorphous Co₃(PO₄)₂–MoO_3−x/NF in turn, a significant optimization of the catalytic activity is achieved. The amorphous state provides an abundance of active sites with unsaturated electronic structures, while the crystalline state offers high conductivity, which synergistically improves overall water-splitting kinetics. The alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can achieve current densities of 100 mA cm⁻² with overpotentials of 101 and 321 mV, respectively. At this current density, the material also demonstrates excellent long-term stability for long-term operation of 100 hours and 80 hours, respectively. In addition, the assembled two-electrode electrolyzer requires a low voltage of 1.51 V to reach a current density of 10 mA cm⁻². This study illustrates the value of crystalline/amorphous heterojunctions in optimizing catalytic activity and provides a new approach for the design and construction of crystalline/amorphous electrocatalysts.