Transition Metal Chalcogenides/MXene Quantum Dot Heterostructure with Polyelectrolyte-Mediated Boosted Charge Separation for Photocatalytic Organic Transformation

MXene quantum dots (QDs) possess the electron-withdrawing capability of MXene nanosheets (NSs) with more abundant active sites, rendering it an emerging charge mediator for photocatalysis. Nevertheless, few MXene QD-based photocatalytic systems have been explored, and the contribution of MXene QDs for the modulation of charge transfer remains elusive. Herein, we show the construction of cascade charge flow over transition metal chalcogenides (TMCs), which are coated via a polyelectrolyte layer of poly(dialyldimethylammonium chloride) (PDDA), followed by MXene QD deposition. It was unleashed that the intermediate PDDA layer serves as a charge relay medium to boost the electron transfer from TMC NSs to MXene QDs, boosting the charge transfer kinetics, promoting the interfacial charge separation, and endowing the TMCs@PDDA-M QD heterostructures with considerably enhanced visible-light-driven photoactivities for reduction of aromatic nitro compounds.