Photo/electro catalytic green hydrogen production promoted by Ga modified Co_0.6Cu_0.4Fe₂O₄ nano catalysts

The current work concentrates on the fabrication of Ga doped Co_0.6Cu_0.4Fe₂O₄ nanocatalysts via sol-gel auto-combustion (SGA) for the production of green and sustainable source of energy i.e., hydrogen through photocatalytic and electrocatalytic routes. Single-phased cubic crystal structure with Fd3m geometry was observed through XRD patterns. FESEM images show the aggregated and spherical shaped grains with distinct grain boundaries and average grain size of 1.04 and 1.39 μm for the Co_0.6Cu_0.4Fe₂O₄, and Co_0.6Cu_0.4Ga_0.02Fe_1.98O₄ nanomaterials. Soft magnetic behaviour with a coercivity (H_c) and saturation magnetization (M_s) of 235.32–357.26 Oe and 54.65–61.11 emu/g was obtained for the produced nanomaterials. The estimation of photocatalytic nature for generating H₂ was conducted using the sacrificial agents i.e., 0.128 M Na₂S and 0.079 M Na₂SO₃. The analysis focused on measuring the maximum H₂ generation was achieved by photocatalysts throughout three consecutive 4-h cycles. Out of all compositions, Co_0.6Cu_0.4Ga_0.02Fe_1.98O₄ nanomaterial have the highest photocatalytic activity of 16.71 mmol g_cat⁻¹. However, the electrocatalytic behaviour of prepared Co_0.6Cu_0.4Ga_xFe_2-xO₄ (x = 0.00–0.03) electrocatalysts were determined for HER (Hydrogen evolution reaction) reaction. The overpotential values of Co_0.6Cu_0.4Fe₂O₄, Co_0.6Cu_0.4Ga_0.01Fe_1.99O₄, Co_0.6Cu_0.4Ga_0.02Fe_1.98O₄, and Co_0.6Cu_0.4Ga_0.03Fe_1.97O₄ catalysts at 10 mA cm⁻² were −0.81, −0.85, −1.03, and 1.21 V, correspondingly. Thus, at cathode current density of 10 mA/cm⁻², an elevation in overpotential was noted, which indicates that the undoped Co_0.6Cu_0.4Fe₂O₄ (x = 0.00) electrocatalyst have remarkable electrocatalytic HER activity. Consequently, owing to photo/electro catalytic water splitting traits, the prepared catalysts are highly efficient for the green hydrogen generation.