Enhanced visible-light-driven hydrogen generation by in situ formed photocatalyst RGO–CdS–NixS from metal salts and RGO–CdS composites

Abstract

Artificial photosynthesis for H₂ production is regarded as a promising strategy to deal with the future energy crisis and environmental problems. To design highly efficient and low-cost photocatalysts is highly desired. Herein, we develop a novel photocatalyst (RGO)_n–CdS–Ni_xS (n = 0–7) in situ made simply from the NiCl₂ precursor and (RGO)_n–CdS composites at room temperature with enhanced visible-light-driven H₂ evolution activity. (RGO)₂–CdS–Ni_xS shows the highest activity for H₂ production in ethanol aqueous solution with a rate up to 17.5 μmol h⁻¹ mg⁻¹, which is about 36 times higher than that of bare CdS, 23.4 times higher than that in the absence of Ni²⁺ ((RGO)₂–CdS), and 2.43 times higher than that in the absence of the graphene scaffold under the same conditions. UV-vis DRS, emission spectra, BET analysis and electrocatalytic activity as well as elemental mapping images suggest that the Ni²⁺ salt is well fabricated on (RGO)₂–CdS for enhanced photocatalytic performance. Accordingly, other metal-based photocatalysts (RGO)₂–CdS–M (M = Co²⁺, Fe²⁺ or Mn²⁺) also exhibit high H₂ evolution activity. This study highlights a simple in situ deposition method to fabricate low-cost and highly active photocatalysts for H₂ production.