Surface engineering of hematite nanorods by 2D Ti3C2-MXene: Suppressing the electron-hole recombination for enhanced photoelectrochemical performance

[Display omitted] •Successful surface engineering of α-Fe2O3 by MXene via facile hydrothermal method.•α-Fe2O3/MXene hybrid NRs photoanode exhibits 7 times enhanced PEC performance.•MXene-derived layer greatly prolongs lifetime of photo-induced holes by 10 times. Photoelectrochemical (PEC) water splitting is a promising approach to improve solar energy conversion, but still suffers from poor efficiency due to intrinsic high charge recombination and low conductivity of semiconductor photocatalysts. In this work, we applied Ti3C2-MXene to construct hematite/MXene nanorods (α-Fe2O3/MXene NRs) with enhanced PEC performance. The as-formed MXene-derived Ti-rich layer could not only serve as a passivation layer to significantly suppress surface electron-hole recombination, but also act as Ti source to promote bulk electron transfer. The optimum α-Fe2O3/MXene5/1 NRs resulted in a 7 times PEC enhancement compared with pristine α-Fe2O3 NRs while maintaining high stability. Mechanism studies by in-situ ultrafast transient absorbance spectra (TAS) directly proved that the duration of the photo-induced holes for optimum α-Fe2O3/MXene NRs was 10 times longer than pristine α-Fe2O3 NRs, proving notably enhanced surface charge separation. This study gives a clue to construct series of MXene based anode materials with promoted performance.