Enhanced Hydrogen Concurrent Production via Urea Solution Electrolysis Using Mesoporous Nickel Tungstate Precipitated from a Surfactant Template

The manipulation of the electrocatalyst nanoarchitecture, particularly transition metal compounds, regarding size, shape, facets, and composition, significantly enhances the electrocatalytic activity in energy transformations. This study introduces a novel methodology for the precipitation of mesoporous nanoparticles of nickel tungstate (meso-NiWO4) using direct chemical deposition from a template of Brij®78 surfactant liquid crystal. Physicochemical analyses revealed the formation of amorphous meso-NiWO4 nanoparticles with dual sizes of 10 ± 3 and 120 ± 8 nm and a specific surface area of 34.2 m2/g, exceeding that of nickel tungstate deposited in the absence of surfactant (bare-NiWO4, 4.0 m2/g). The meso-NiWO4 nanoparticles exhibit improved electrocatalytic stability, reduced charge-transfer resistance (Rct = 1.11 ohm), and a current mass activity of ~365 mA/cm2 mg at 1.6 V vs. RHE during the electrolysis of urea in alkaline solution. Furthermore, by employing meso-NiWO4 in a two-electrode urea electrolyzer, a remarkable 4.8-fold increase in the cathodic hydrogen concurrent production rate was achieved (373.40 µmol/h at a bias potential of 2.0 V), compared to that of the bare-NiWO4 catalyst. The exceptional urea oxidation electroactivity and the enhanced hydrogen evolution rate arise from substantial specific surface area and mesoporous structure, facilitating effective charge transfer and mass transport through the meso-NiWO4 catalyst. Using the surfactant liquid crystal template for electrocatalyst synthesis enables a one-pot deposition of diverse nanoarchitectures and compositions with high surface area at ambient conditions for an improved electrocatalytic and hydrogen green production process.