Electrospun Ni₃(BO₃)₂–NiO Heterointerface for Boosted Overall Water Splitting andSolar-to-Hydrogen Conversion

The development of low-cost, long-lasting, and high-performance bifunctional electrocatalysts is needed for effective electrochemical water splitting. Herein, an interface-boration engineering strategy was used to synthesize heterostructured nickel borate–nickel oxide (Ni₃(BO₃)₂–NiO) by using the electrospinning-incineration process, which exhibited an unprecedentedly high electrocatalytic activity in alkaline media. The Ni₃(BO₃)₂–NiO electrode showed ultralow oxygen evolution reaction and hydrogen evolution reaction overpotentials of 261 and 150 mV, respectively, to achieve 10 mA cm^–2. For Ni₃(BO₃)₂–NiO/NF-assisted alkaline as well as solar-driven electrolyzers, a low cell voltage of 1.60 V was needed to drive 10 mA cm^–2 and their catalytic activity was maintained for 40 h, indicating significant potential for their use in water-splitting. Ni₃(BO₃)₂–NiO was employed to generate H₂ effectively by consuming a power of 732.33 L_H₂ kW h^–1 lower than that of cNiO (835 L_H₂ kW h^–1). The enhanced adsorption of oxygen-containing Lewis base intermediates on Ni₃(BO₃)₂–NiO by Lewis acid–base interactions boosted the catalytic performance. This work provides a newer direction toward the rational engineering of the metal borate–metal oxide heterostructure with excellent intrinsic characteristics for energy applications, upscaled to industrial-scale H₂ production due to production simplicity.