2D/2D type-II Cu2ZnSnS4/Bi2WO6 heterojunctions to promote visible-light-driven photo-Fenton catalytic activity

In this work, a set of novel Cu2ZnSnS4/Bi2WO6 (CZTS/BWO) two-dimensional (2D)/two-dimensional (2D) type-II heterojunctions with different CZTS weight ratios (1%, 2%, and 5%) were successfully synthesized via a brief secondary solvothermal process. The successful formation of the heterojunctions was affirmed by characterization methods such as X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. The photocatalytic activity results showed that the prepared CZTS/BWO heterojunctions had excellent photocatalytic behaviors for organic degradation, especially when the mass fraction of CZTS with respect to BWO in the composite was 2%. Moreover, the addition of hydrogen peroxide (H2O2) could further improve the dye and antibiotic degradation efficiencies. The reinforced photocatalytic and photo-Fenton degradation performance were primarily attributable to the introduction of BWO, which afforded increased active sites, expanded the solar spectral response range, and accelerated the cycle of Cu(II)/Cu(I); after four cycling times, its catalytic activity did not decrease significantly. In addition, reasonable hypotheses of the photocatalytic and photo-Fenton catalytic mechanisms were formulated. This study is expected to provide a visual approach for designing a novel photo-Fenton catalyst to jointly utilize the photocatalytic and Fenton activities, which can be better applied to the purification of residual organics in wastewater. (C) 2020, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.