Transition metal (Ni, co)-doped graphitic carbon nitride/MoS2 heterojunctions as efficient photocatalysts for hydrogen evolution reaction under visible light

New photocatalysts comprising the 2D/2D heterojunction of graphitic carbon nitride (gCN) and molybdenum disulfide (MoS2) semiconductors doped with nickel (Ni) or cobalt (Co), denoted as gCN/MoS2-M (M: Ni, Co), were fabricated for the photocatalytic hydrogen evolution reaction (HER) under visible light illumination. First, the binary gCN/MoS2 heterojunctions were fabricated by using an in-situ solvothermal method and then they were doped with Ni or Co via a chemical reduction method. The photocatalytic HER experiments revealed that the prepared gCN/MoS2-M (M: Ni, Co) photocatalysts showed enhanced HER activities and stabilities compared to pristine gCN and binary gCN/MoS2 heterojunctions. Total H-2 productions of 5924 mu mol g(cat)(-1) and 5159 mu mol g(cat)(-1) in 8 hours were provided by using gCN/MoS2-Ni and gCN/MoS2-Co photocatalysts, respectively, under visible light illumination. The detailed structural characterization and examination of optical properties of gCN/MoS2-M (M: Ni, Co) photocatalysts revealed that their enhanced photocatalytic activities were attributed to the formation of 'type-I' 2D/2D heterojunction between gCN and MoS2 semiconductors and the creation of S-deficient MoS2 nanostructures after Ni or Co doping, which promoted the separation of the photogenerated electron-hole pairs, the charge mobility, and the visible light absorption.

Automated summary

New photocatalysts consisting of 2D/2D heterojunction of graphitic carbon nitride (gCN) and molybdenum disulfide (MoS2) semiconductors doped with nickel (Ni) or cobalt (Co) were fabricated for the photocatalytic hydrogen evolution reaction (HER) under visible light illumination. The prepared gCN/MoS2-Ni and gCN/MoS2-Co photocatalysts exhibited enhanced HER activities and stabilities compared to pristine gCN and binary gCN/MoS2 heterojunctions.