Efficient Self-Powered Overall Water Splitting by Ni₄ Mo/MoO₂ Heterogeneous Nanorods Trifunctional Electrocatalysts

The exploration of cost-effective multifunctional electrodes with high activity toward energy storage and conversion systems, such as self-powered alkaline water electrolysis, is very meaningful, although studies remain quite limited. Herein, a heterogeneous nickel-molybdenum (NiMo)-based electrode is fabricated for the first time as a trifunctional electrode for asymmetric supercapacitor (ASC), hydrogen evolution reaction, and oxygen evolution reaction. The trifunctional electrode consists of Ni₄ Mo and MoO₂ (denoted Ni₄ Mo/MoO₂ ) with hierarchical nanorod heterostructure and abundant heterogeneous nanointerfaces creating sufficient active sites and efficient charge transfer for achieving high performance self-power electrochemical devices. The ASC consists of the as-prepared Ni₄ Mo/MoO₂ positive electrode, showing a broad potential window of 1.6 V, and a maximum energy density of 115.6 Wh kg^-1 , while the alkaline overall water splitting (OWS) assembled using the as-prepared Ni₄ Mo/MoO₂ as bifunctional catalysts only requires a low cell voltage of 1.48 V to achieve a current density of 10 mA cm^-2 in aqueous alkaline electrolyte. Finally, by integrating the Ni₄ Mo/MoO₂ -based ASC and OWS devices, an aqueous self-powered OWS is assembled, which self-power the OWS to generate hydrogen gas and oxygen gas, verifying great potential of the as-prepared Ni₄ Mo/MoO₂ for sustainable and renewable energy storage and conversion system.