Black Ultrathin Single‐Crystalline Flakes of CuVP2S6 and CuCrP2S6 for Near‐Infrared‐Driven Photocatalytic Hydrogen Evolution

Abstract

AbstractThe development of new near‐infrared‐responsive photocatalysts is a fascinating and challenging approach to acquire high photocatalytic hydrogen evolution (PHE) performance. Herein, near‐infrared‐responsive black CuVP2S6 and CuCrP2S6 flakes, as well as CuInP2S6 flakes, are designed and constructed for PHE. Atom‐resolved scanning transmission electron microscopy images and X‐ray absorption fine structure evidence the formation of ultrathin single‐crystalline sheet‐like structure of CuVP2S6 and CuCrP2S6. The synthetic CuVP2S6 and CuCrP2S6, with a narrow bandgap of ≈1.0 eV, shows the high light‐absorption edge exceeding 1100 nm. Moreover, through the femtosecond‐resolved transient absorption spectroscopy, CuCrP2S6 displays the efficient charge transfer and long charge lifetime (18318.1 ps), which is nearly 3 and 29 times longer than that of CuVP2S6 and CuInP2S6, respectively. In addition, CuCrP2S6, with the appropriate d‐band and p‐band, is thermodynamically favorable for the H+ adsorption and H2 desorption by contrast with CuVP2S6 and CuInP2S6. As a result, CuCrP2S6 exhibits high PHE rates of 9.12 and 0.66 mmol h−1 g−1 under simulated sunlight and near‐infrared light irradiation, respectively, far exceeding other layered metal phospho–sulfides. This work offers a distinctive perspective for the development of new near‐infrared‐responsive photocatalysts.