Electrocatalytic hydrogen evolution reaction studies of NiW_1−xMo_xO₄ (x = 0.0, 0.5 and 1.0) nanoparticles in both acid and alkaline electrolytes

In this work, NiW_1−xMo_xO₄ (x = 0.0, 0.5 and 1.0) nanoparticles (NPs) are synthesized by sonochemical method followed by high temperature calcination. The prepared samples are characterized using various techniques. The crystallinity and the presence of functional groups were identified using XRD and FT-IR spectra, respectively. FE-SEM confirmed the morphological characteristics of the synthesized material. Finally, the electrochemical properties of the synthesized materials were analysed using CV and LSV techniques both in alkaline and in acidic media under ambient atmosphere. Among, the prepared NiMo_0.5W_0.5O₄ (24 nm) delivered enhanced hydrogen evolution reactions (HERs) activity than NiWO₄ (32 nm), NiMoO₄ (163 nm) NPs. The NiMo_0.5W_0.5O₄ as the electrocatalysts for HER exhibited a lower overpotential (97 mV) and minimal Tafel value (48 mV dec⁻¹) towards HER in the acid medium compared to alkaline media. Further, the OER polarization curve also studied to identify the bifunctional electrocatalytic activity of NiW_0.5Mo_0.5O₄ in the optimized electrolyte.