Structure engineering of 1T/2H multiphase MoS2 via oxygen incorporation over 2D layered porous g-C3N4 for remarkably enhanced photocatalytic hydrogen evolution

Abstract

Two-dimension (2D) layered porous graphite-like carbon nitride (p-g-C3N4) has shown broad prospect in photocatalytic H2 generation due to its simple synthesis, low cost, unique porous 2D layered structure, excellent chemical and thermal stability, an appropriate band gap as well as more negative conduction band position with stronger reduction capacity. Yet, direct and efficient photocatalytic hydrogen evolution (HER) activity of bare p-g-C3N4 encountered a huge restriction of the rapid recombination of photocarriers. Herein, we study that oxygen incorporating 1T and 2H multiphase MoS2 (O-1T/2H–MoS2) as a cocatalyst can promote p-g-C3N4 nanosheets (NSs) to realize tremendously efficient photocatalytic H2 production. The prepared O-1T/2H–MoS2/g-C3N4 hybrids display extremely boosted photocatalytic H2 generation performance and outstanding cycle stability. The optimized 7%-O-1T/2H–MoS2/g-C3N4 hybrids show a tremendously improved photocatalytic H2 evolution rate of 1487 μmol/h/g, which is approximately 297 and 11 times of bare p-g-C3N4 (5 μmol/h/g) and 7 wt %-1T/2H–MoS2/p-g-C3N4 hybrids (140 μmol/h/g), respectively. Besides, the apparent quantum efficiency (AQE) of all the samples was computed under the light at λ = 370 nm, in which the AQE of 7%-O-1T/2H–MoS2/g-C3N4 hybrids is up to 20.32%. The experimental data and the DFT calculation suggest that the excellent HER activity of O-1T/2H–MoS2/g-C3N4 hybrids is attributed to the O doping causing the distortion of MoS2 crystal where O displaced some S atoms in 1T/2H–MoS2 to adjust the electronic structure and further promote conductivity as well as produce a lot of active sites, which also effectively decreases the H binding free energy for HER. Accordingly, the O-1T/2H–MoS2 cocatalyst loading effectively boosted the photocatalytic activity of p-g-C3N4 for H2 evolution. And the project promotes fast development on the progress of low-cost and high-efficiency photocatalysts for photocatalytic H2 generation.