Graphitic carbon nitride/antimonene van der Waals heterostructure with enhanced photocatalytic CO2 reduction activity

Abstract

Photocatalytic reduction of CO 2 into valuable fuels is one of the potential strategies to solve the carbon cycle and energy crisis. Graphitic carbon nitride (g-C 3 N 4 ), as a typical two-dimensional (2D) semiconductor with a bandgap of ∼2.7 eV, has attracted wide attention in photocatalytic CO 2 reduction. However, the performance of g-C 3 N 4 is greatly limited by the rapid recombination of photogenerated charge carriers and weak CO 2 activation capacity. Construction of van der Waals heterostructure with the maximum interface contact area can improve the transfer/seperation efficiency of interface charge carriers. Ultrathin metal antimony (Sb) nanosheet (antimonene) with high carrier mobility and 2D layered structure, is a good candidate material to construct 2D/2D Sb/g-C 3 N 4 van der Waals heterostructure. In this work, the density functional theory (DFT) calculations indicated that antimonene has higher carrier mobility than g-C 3 N 4 nanosheets. Obvious charge transfer and in-plane structure distortion will occur at the interface of Sb/g-C 3 N 4 , which endow stronger CO 2 activation ability on di-coordinated N active site. The ultrathin g-C 3 N 4 and antimonene nanosheets were prepared by ultrasonic exfoliation method, and Sb/g-C 3 N 4 van der Waals heterostructures were constructed by self-assembly process. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) indicated that the Sb/g-C 3 N 4 van der Waals heterostructures have a better photogenerated charge separation efficiency than pure g-C 3 N 4 nanosheets. In-situ FTIR spectroscopy demonstrated a stronger ability of CO 2 activation to *COOH on Sb/g-C 3 N 4 van der Waals heterostructure. As a result, the Sb/g-C 3 N 4 van der Waals heterostructures showed a higher CO yield with 2.03 umol g −1 h −1 , which is 3.2 times that of pure g-C 3 N 4 . This work provides a reference for activating CO 2 and promoting CO 2 reduction by van der Waals heterostructure.