Design and construction of double heterojunction is favorable to improve the separation and migration efficiency of photogenerated carriers, thus preferably solve the problems of environmental pollution and energy crisis. Herein, TiO2 nanoparticles (NPs) are in-situ grown on highly conductive Ti3C2 nanosheets via low-temperature hydrothermal strategy, and then black phosphorus quantum dots (BPQDs) are introduced on the surface of TiO2 NPs. Under hydrothermal temperature 120 °C, the BPQDs/Ti3C2@TiO2 photocatalyst exhibits remarkable enhanced photocatalytic degradation of methyl orange (MO) and hydrogen evolution reaction (HER) compared with BPQDs/Ti3C2 and Ti3C2@TiO2 composites. Enhanced photocatalytic activity can be attributed to (i) the BPQDs with tunable bandgaps are deposited on the TiO2 NPs to form intimate heterojunction, which facilitates the electrons transfer from the conduction band (CB) of BPQDs to the CB of TiO2; (ii) the electrons quickly migrate from CB of TiO2 NPs to the Ti3C2 nanosheets with excellent electronic conductivity via electron transfer channel, which is beneficial to prolong the lifetime of electrons and hinder the recombination of photogenerated carriers; (iii) the enhanced visible light absorption and enlarged specific surface area of BPQDs/Ti3C2@TiO2 further accelerate the photocatalytic reaction. This work emphasizes the essential role of quantum dots in the construction of double heterojunction and the potential application of Ti3C2 MXene for improving photocatalytic activity.
Keywords: charge transfer; double heterojunction; hydrogen evolution reaction; photocatalytic degradation.