Abstract
•Fe3O4 derived from iron scrap enhanced TiO2-Fe3O4 photocatalytic activity.•Iron scrap proved to be a sustainable precursor for Fe3O4 synthesis.•Fe3O4 reduced the bandgap to 1.45 eV extending visible light absorption.•Fe3O4 prolonged the charge separation of TiO2-Fe3O4 via its Fe2+/Fe3+ states.•TiO2(1)-Fe3O4(0.25) showed an excellent photocatalytic and photoelectric features.
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)-Fe3O4(0.25) as compared to pure TiO2 (0.07 mA cm-2, 24.80 Ω, and 0.40 ms). In comparison, TiO2(1)-Fe3O4(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.
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