The Intrinsic Relationship between Photoluminescence and Photocatalysis of MMoO4/MWO4 (M = Mg, Ca, Sr and Ba) Heterojunctions: Heterojunction Construction, Mechanism Insight and Development Tendency

The migration behavior of electron and hole pairs determines both photoluminescence and photocatalytic activity, which are two distinct properties of semiconductor materials. The photoluminescence and photocatalytic activity of semiconductor materials also exhibit strong method-dependent behavior under the influence of synthesis methods. In this review, the synthesis methods of MMoO4, MWO4 and MMoO4/MWO4 (M = Mg, Ca, Sr and Ba) heterojunction composites and their photoluminescence and photocatalytic activities are reviewed for the first time. The effects of different M ions on the photoluminescence and photocatalytic activity of MMoO4/MWO4 heterojunction composites are also reviewed. There is also a discussion about the intrinsic correlation mechanism between photoluminescence and photocatalytic activity. Different M ions result in different coordination environments in MMoO4/MWO4 heterojunction composites, which leads to different photoluminescence and photocatalytic mechanisms of different MMoO4/MWO4 heterojunction composites. This review provides theoretical reference and technical guidance for future research on MMoO4/MWO4 heterojunction composites.