Mo2CF2/WS2: Two-Dimensional Van Der Waals Heterostructure for Overall Water Splitting Photocatalyst from Five-Step Screening

Abstract

With the increasing demand for renewable energy and clean energy, photocatalysis is considered an economical and feasible source of energy. In this work, we select two-dimensional (2D) materials of X2CT2 (X = Cr, Hf, Mo, Sc, Ti, Zr; T = Cl, F, O, OH), Mxene, and MS2 (M = Mo, W) to form 20 systems of 2D van der Waals (vdW) heterostructures. We establish five screening steps, and the 2D Mo2CF2/WS2 vdW heterostructures meet all the screening conditions. Mo2CF2/WS2 is a type II semiconductor with a band gap of 1.58 eV, proper band edge position and high solar-to-hydrogen efficiency (17.15%) and power conversion efficiency (23.4%). An excellent electron-hole recombination time of 21.2 ps and electron (hole) migration time of 149 (265) fs are obtained in the 2D Mo2CF2/WS2 vdW heterostructure. In addition, the calculation results of Gibbs free energy show that a hydrogen reduction reaction and water oxidation reaction can proceed smoothly under the driving of photogenerated holes.