Photocatalytic and photoelectrochemical performance of CoFe2O4 spinel for visible-light-driven hydrogen generation

Hydrogen is a clean and sustainable energy source, making the development of efficient production technologies essential for meeting global energy demands and mitigating carbon emissions. In this study, the optical and photo-electrochemical properties of CoFe₂O₄ (CFO) nanoparticles have been investigated, highlighting their effectiveness in hydrogen generation. CFO was synthesized using the wet method and formed at 700 °C, the spinel was identified by X-ray diffraction (XRD), FTIR spectroscopy, Raman, and X-ray photoelectron spectroscopy (XPS). The XRD pattern revealed a cubic phase, with a lattice constant of 8.0374 Å and a crystallite size of 36 nm. The morphology was examined by scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX). The gap of CFO, obtained from UV–VIS diffuse reflectance spectroscopy, was 1.46 eV. The flat band potential (E_fb = 0.06 V_SCE) was obtained from the capacitance-potential (C⁻²—E) characteristic in NaOH (0.1 M) solution with p-type behavior. The cyclic voltammetry of CFO indicated favorable hydrogen generation under visible light irradiation, with a potential of -0.7 V_SCE. An H₂ liberation rate of 48 μmol min⁻¹g⁻¹ was reached under optimal conditions: 1g/L of catalyst, basic medium NaOH at a temperature of 50 °C in the presence of hole scavenger SO₃²⁻ (10^–3 M).