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

Abstract

• Fe 3 O 4 derived from iron scrap enhanced TiO 2 -Fe 3 O 4 photocatalytic activity. • Iron scrap proved to be a sustainable precursor for Fe 3 O 4 synthesis. • Fe 3 O 4 reduced the bandgap to 1.45 eV extending visible light absorption. • Fe 3 O 4 prolonged the charge separation of TiO 2 -Fe 3 O 4 via its Fe 2+ /Fe 3+ states. • TiO 2(1) -Fe 3 O 4(0.25) showed an excellent photocatalytic and photoelectric features. In this work, the hybridization effect of iron scrap-derived Fe 3 O 4 on TiO 2 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 Fe 3 O 4 , which was then tailored with TiO 2 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 H 2 O 2 concentration, and 1 number of plates. XRD, Raman, and SEM confirmed the successful production of Fe 3 O 4 and TiO 2 -Fe 3 O 4 hybridization. UV-Vis DRS showed a significant reduction in bandgap from 2.41 eV to 1.45 eV with an increase in Fe 3 O 4 composition as compared to pure TiO 2 (3.05 eV), extending the light absorption into the visible region. In addition, PL revealed prolonged electron-hole recombination in TiO 2 -Fe 3 O 4 hybrid, confirming an improved charge separation due to Fe 3 O 4 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 TiO 2(1) -Fe 3 O 4(0.25) as compared to pure TiO 2 (0.07 mA cm -2 , 24.80 Ω, and 0.40 ms). In comparison, TiO 2(1) -Fe 3 O 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 Fe 2+ /Fe 3+ (Fe 3 O 4 ) for photocatalytic applications.