Insight into hybridization of iron scrap derived Fe₃O₄ on TiO₂: Facile synthesis of an eco-friendly photocatalyst, characterization, and photoelectric properties

In this work, the hybridization effect of iron scrap-derived Fe₃O₄ on TiO₂ was investigated to develop an efficient, eco-friendly photocatalyst with enhanced photoelectric properties. A green and facile synthesis approach designed with Response Surface Methodology (RSM) was employed, using iron scrap as a sustainable precursor for obtaining Fe₃O₄, which was then tailored with TiO₂ to create the desired hybrid photocatalyst. RSM-quadratic model results showed the optimum conditions to achieve a 100 % Fe dissolution efficiency were 0.967 M citric acid concentration, 7.167 days, 8.358 M H₂O₂ concentration, and 1 number of plates. XRD, Raman, and SEM confirmed the successful production of Fe₃O₄ and TiO₂-Fe₃O₄ hybridization. UV–Vis DRS showed a significant reduction in bandgap from 2.41 eV to 1.45 eV with an increase in Fe₃O₄ composition as compared to pure TiO₂ (3.05 eV), extending the light absorption into the visible region. In addition, PL revealed prolonged electron-hole recombination in TiO₂-Fe₃O₄ hybrid, confirming an improved charge separation due to Fe₃O₄ mixed valence state structure, which prevents charge carrier accumulation and induces electron hopping between the Fe ions. Furthermore, comprehensive photoelectrochemical analysis revealed an excellent photocurrent response (0.03 mA cm^-2) and charge transfer resistance (26.03 Ω) with an increased electron lifetime (2.52 ms) for TiO₂₍₁₎-Fe₃O_4(0.25) as compared to pure TiO₂ (0.07 mA cm^-2, 24.80 Ω, and 0.40 ms). In comparison, TiO₂₍₁₎-Fe₃O_4(0.25) can offer a superior sustained redox catalysis due to its relatively high photocurrent density with a long electron lifetime. Iron scrap can be considered sustainable and tunable Fe²⁺/Fe³⁺ (Fe₃O₄) for photocatalytic applications.