Smallest and High-Performance NiWO ₄ Nanoparticles Supported on MWCNTs as Versatile Electrocatalysts for Hydrogen Production via Three Different Electrooxidation Reactions

Exploring inexpensive, high-performance, and highly stable electrocatalysts for green hydrogen production via electrochemical water splitting is still challenging to expand commercially due to the associated cost of production. Here, robust high-performance NiWO4 nanoparticles of an average size of 4.6 nm have been synthesized and highly dispersed on multiwalled carbon nanotubes (MWCNT) by the hydrothermal method. This average size is the smallest for undoped NiWO4 nanoparticles known to date. We systematically have compared the role of carbon support, revealing its advantages in enhancing the activity and stability over unsupported NiWO4 for alkaline water splitting. Electrolyte engineering with the urea oxidation reaction (UOR) or hydrazine oxidation reaction (HzOR) at the anode replaces the energy-intensive oxygen evolution reaction (OER), drastically lowering the thermodynamic potentials. NiWO4 grown on MWCNT via interface engineering can provide high mechanical stability, alter adsorption energies, and create more active sites. Electrolyte engineering, which includes the exploration of alternative oxidation reactions, provides an energy-efficient method for hydrogen production. A two-electrode water electrolyzer with NiWO4/MWCNT∥NiWO4/MWCNT delivered cell voltages of 1.65, 1.49, and 0.38 V at 10 mA cm–2 in 1.0 M KOH, 0.5 M urea +1.0 M KOH, and 0.5 M hydrazine +1.0 M KOH, respectively, offering an energy-efficient pathway for scalable hydrogen production.