Synthesis of lead-free Cu/CuFeO₂/CZTS thin film as a novel photocatalytic hydrogen generator from wastewater and solar cell applications

The sewage water is tested as a source of hydrogen production with a high efficiency value of 25.44% using Cu/CuFeO₂ (delafossite)/CZTS (Cu₂ZnSnS₄, kesterite) as an investigated photocatalyst. The X-ray diffraction (XRD) analysis of the investigated photocatalyst (Cu/CuFeO₂/CZTS) revealed a compact crystalline material, as witnessed by the diffraction peaks with high intensities. From the optical characterization, the recorded band gap values of Cu/CuFeO₂/CZTS, Cu/CuFeO₂, and CZTS are 1.15, 1.97, and 1.43 eV, respectively, inferring an obvious enhancement in the optical properties of the investigated photocatalyst, Cu/CuFeO₂/CZTS. The photoelectrochemical (PEC) performance of the investigated photocatalyst for hydrogen (H₂) generation was examined in wastewater. The current–time characteristic and the PEC behavior of Cu/CuFeO₂/CZTS in dark and under light illumination using various power densities, monochromatic wavelengths, and different temperatures were studied. The current densities (J_Ph) under light illumination and (J_o) in the dark were − 8.0 and − 0.7 mA cm⁻², respectively. The H₂ generation rate for the Cu/CuFeO₂/CZTS electrode was 0.049 mA/h. The thermodynamic parameters, respectively, ΔS^*, ΔE, and ΔH^* were 28.76 kJ mol⁻¹ K⁻¹, 21.0, and 18.28 kJ mol⁻¹ at 390 nm. The findings of the work hold great promise for addressing energy production and the hindrances of sewage treatment at the same time.