Electrophoretic Deposition of MoSe₂–MoO_x Nanosheets for Enhanced Electrocatalytic Hydrogen Evolution Reaction

Herein, we report an electrophoretically prepared electrode based on photosensitive 2D-MoSe2–MoOx for electrocatalytic hydrogen evolution reaction (HER). Large-area and binder-free electrodes show rapid electrocatalysis due to suitable intrinsic properties such as low charge-transfer resistance, an onset potential of −160 mV versus RHE (reversible hydrogen electrode), an overpotential of about −210 mV versus RHE at −10 mA/cm2, and a double-layer capacitance of 16.2 mF/cm2. Furthermore, injection of photogenerated electrons leads to an onset potential as low as −90 mV versus RHE and an overpotential of −150 mV versus RHE under the illumination of visible light. The photocathode demonstrates excellent photoresponsivity in the spectral range 390–670 nm. The electrode exhibits photocurrents of 0.42 mA/cm2 at 0 mV and 10.19 mA/cm2 at −240 mV versus RHE under the illumination of 670 nm, 30 mW/cm2 light. Owing to optimized light-harvesting abilities, 2D-MoSe2–MoOx demonstrates a high photoresponsivity of 0.34 A/W (1.4 × 10–2 A/W) and an external quantum efficiency of 62.9% (2.6%) at −240 mV (0 mV) versus RHE. Finally, the photocathode encourages the use of sunlight for increasing the rate of electrocatalytic HER for the production of clean energy.