CoMoO4||CoMoP-based nanocolumn self-supporting electrode for overall water splitting

The advancement of stable and highly efficient non-noble metal-based bifunctional electrocatalysts represents a formidable challenge in the realm of overall water splitting technology. In this study, CoMoO₄||CoMoP-based nanocolumn arrays were designed and synthesized using Co-doped molybdophoxide polyoxometalate (PMo), which is grown in situ on nickel foam (NF). Co doping is employed to conduct appropriate electronic modulation of Mo, thereby enhancing the hydrogen evolution reaction (HER) performance. When used in oxygen evolution reaction (OER), surface reconstruction is induced by electrochemical activation, in which the stable structure of PMo serves to balance the newly formed active OER amorphous metal hydroxy-oxide (hydroxide) compounds. The sample exhibits a HER overpotential of 96 mV and an OER overpotential of 234 mV at a current density of 10 mA·cm⁻². When utilizing CoMoO₄||CoMoP-based catalyst as both the cathode and anode assembly, the overall water splitting system can provide a current density of 10 mA·cm⁻² at a driving voltage of merely 1.509 V, and can achieve long-term stability over 100 h, outperforming most previously reported bifunctional electrocatalysts. This work offers a promising approach for constructing high-performance bifunctional electrocatalysts.