The regulating effect of twisted angle on the photocatalytic overall water splitting for C3N/C3B heterojunction

Abstract

The construction of van der Waals heterojunctions for photocatalytic overall water splitting is a promising strategy for obtaining clean energy. Good carrier separation, broadened photo-absorption, and efficient catalytic activity are crucial factors remaining significantly challenging. Herein, based on first-principles calculations, taking C3N/C3B as an example, we demonstrate that the suitable twisted angle (θ) formed in the layered structure is an efficient strategy to regulate photocatalytic properties of two-dimensional materials. For the heterojunctions stacked with θ = 19.1° and 40.9°, the layer-to-layer interaction introduced by the moiré pattern provides an electrostatic potential difference of up to 2.1 eV, about 0.8 eV higher than non-twisted. The enhanced built-in electric field not only alleviates the redox potential limit of water splitting but also promotes the transfer of photogenerated carriers. Meanwhile, the twisted C3N/C3B improves the visible light response by opening the transition channels in the low-energy region. Especially for the difficult four-electron oxygen evolution reaction, the overpotential is reduced from 0.70 to 0.52 V based on the moiré potential, which can be easily conquered for the twisted C3N/C3B with sufficient redox potential. Interlayer torsion provides an effective regulation strategy to improve the photocatalytic overall water splitting performance for metal-free heterojunctions.