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, MnO 2 @Ni 3 Se 2 /NF, engineered via heterogeneous interface modification. The integrated Ni 3 Se 2 /MnO 2 heterostructures demonstrate bifunctional catalytic synergy for selective methanol oxidation and hydrogen evolution. The complementary electronic configurations between Ni 3 Se 2 and MnO 2 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 MnO 2 @Ni 3 Se 2 /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.