S-scheme heterojunction of core–shell biphase (1T-2H)-MoSe2/TiO2 nanorod arrays for enhanced photoelectrocatalytic production of hydrogen peroxide

Developing high-performance photocatalytic electrodes is significant for realizing the efficient photoelectrocatalytic generation of H2O2 for converting naturally available chemicals. It is also a challenge to achieve high conversion efficiencies. Herein, we construct a step-scheme (S-scheme) heterojunction using core–shell 2H semiconductor MoSe2 phase at TiO2 nanorod arrays (2H-MoSe2/TiO2 NRAs) with an in-situ synthesis of 1 T metallic phase in the initial 2H-MoSe2 overlayer to build coupled, biphasic (1 T-2H)-MoSe2/TiO2 NRAs successfully. This S-scheme heterojunction of both 2H-MoSe2/TiO2 NRAs and (1 T-2H)-MoSe2/TiO2 NRAs presents excellent photoelectrocatalytic activities for H2O2 production under ultraviolet light illumination. The former yields an H2O2 production rate that is 3.3 times as high as the pristine TiO2 NRAs, while the latter biphasic interface achieves a 4.7-fold enhancement. The 1 T metallic MoSe2 plays a vital role as the charge carrier transfer bridge between 2H-MoSe2 and TiO2 to promote the S-type charge transportation. Further DFT calculations and experimental results indicate that the MoSe2 overcoating could effectively suppress H2O2 decomposition. This work provides a promising strategy to construct high-performance S-scheme heterojunctions through in-situ interface modulation.