The ability of CaFe2O4 manufactured through a straightforward nitrate method for effective H2 generation

Abstract

Researchers are now working on creating a highly effective solar-powered device that splits water using a catalyst, addressing the energy crisis and generating green hydrogen. Herein, calcium spinel ferrite CaFe₂O₄ was successfully employed as a photocatalyst for hydrogen production under visible lighting. CaFe₂O₄ was prepared using the nitrate route method with nitrates as salt precursors, followed by calcination at 850 °C. Thermal analysis (TGA-DT), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), UV visible diffuse reflectance, FT-IR spectroscopy, and scanning electron microscopy (SEM/EDX) were used for structural, compositional, morphological, and optical characterization of the prepared material. XRD verified a single phase of CaFe₂O₄, showing an orthorhombic structure with a mean crystallite size of 31 nm. The direct band gap of 1.85 eV was estimated from diffuse reflectance data. SEM micrographs exhibited heterogeneous grains with irregular shapes and medium porosity. EDX elemental analysis revealed the occurrence of Ca, Fe, and O, indicating the high purity of the prepared material, while XPS analysis supported these results. The photocatalytic ability of the resultant sample showed optimal hydrogen generation of approximately 139.04 μmol in a Na₂SO₄ electrolyte (10⁻³ M) upon visible exposure, even lacking hole scavengers. Interestingly, the occurrence of SO₃²⁻ as hole scavengers increased the hydrogen generation by 1.19 times after 30 min of illumination. Also, the stability of the sample was also evaluated throughout 3 straight uses, demonstrating promising stability with a performance drop of (∼21 %). Considering the simplified manufacturing approach and remarkable effectiveness, this research argues that CaFe₂O₄ might be a promising photocatalyst for renewable and green energy generation.