Direct Z-scheme Fe₂(MoO₄)₃/MoO₃ heterojunction: Photo-Fenton reaction and mechanism comprehension

The photo-Fenton reaction consisted of photocatalytic reaction and heterogeneous Fenton reaction is an effective technique for pollutant degradation, because the degradation rate is faster than individual reactions. In this work, Fe₂(MoO₄)₃/MoO₃ heterojunction was prepared via a grinding-calcination method. Work function measurement indicated that the inner electric field was build at the interface between Fe₂(MoO₄)₃ and MoO₃, leading to a Z-scheme electron (e^-) transfer pathway, and this result was supported by the radical quenching experiment and band structure analysis. In photo-Fenton reaction, the degradation rate was 57 and 170 times higher than those in heterogeneous Fenton reaction and photocatalytic reaction, respectively. This improvement was because H₂O₂ not only served as an oxidant in heterogeneous Fenton reaction, but also acted as scavenger of e^- in photocatalytic reaction. Synergistic effect was established between heterogeneous Fenton reaction and Z-scheme photocatalytic process via H₂O₂ as a medium, and 1140% extra degradation efficiency was yielded by coupling these two reactions together. Besides high activity, 92.6% of degradation efficiency was remained after the 5^th cycle, indicating an outstanding recyclability.