Boosting Synergistic Methanol Oxidation and Hydrogen Evolution via MnO₂-Decorated Ni₃Se₂/NF Heterojunction Catalysts for Low-Voltage Water Splitting

The anodic oxygen evolution reaction (OER) is characterized by intrinsically slow kinetics, constituting a fundamental bottleneck that restricts the overall efficiency of conventional water electrolysis systems. To address this challenge, we investigate methanol oxidation as a viable alternative to the OER for the anodic reaction, reducing energy input requirements. Here, we report the synthesis of a self-supported heterojunction catalyst, MnO2@Ni3Se2/NF, engineered via heterogeneous interface modification. The integrated Ni3Se2/MnO2 heterostructures demonstrate bifunctional catalytic synergy for selective methanol oxidation and hydrogen evolution. The complementary electronic configurations between Ni3Se2 and MnO2 synergistically regulate intermediate adsorption energetics, while interfacial charge redistribution facilitates the in situ generation of catalytically active high-valent Ni species. As a result, the optimized MnO2@Ni3Se2/NF electrode demonstrates enhanced charge transfer kinetics and reduced activation barriers, delivering a methanol oxidation current density of 100 mA cm–2 at 1.36 V. Moreover, in a coelectrolysis system, the catalyst enables simultaneous hydrogen evolution and methanol oxidation, achieving overall water splitting (OWS) with a current density of 100 mA cm–2 at a lower input voltage of 1.60 V with sustained operational stability exceeding 100 h. This highlights the high energy conversion efficiency of methanol-assisted hydrogen production and demonstrates its significant potential for sustainable hydrogen generation.