Hydrogen evolution properties of Cr doped and (Cr, Er) co-doped ZnS nanoparticles

Abstract

In this study, the influence of transition metal ion doping and rare earth ion co-doping on the structural, optical, and hydrogen (H-2) production properties of nanocrystalline ZnS were estimated. A simple hydrothermal technique was utilized to prepare the ZnS, ZnS:Cr, and ZnS:(Cr,Er) nanoparticles (NPs). Comprehensive structural analysis confirming the effectual incorporation of Cr and Er in the place of Zn in ZnS matrix without disturbing the original structure. An-X-ray photoelectron narrow scans confirming the existence of zinc, sulfur, chromium, and erbium in the prepared sample as 2+, 2-, 3+, and 3+ chemical states, respectively. Surprisingly, the optical bandgap of ZnS was slightly enhanced after doping and co-doping. Anticipatedly, ZnS:(Cr,Er) system displayed highest H-2 production than those of ZnS and ZnS:Cr samples beneath artificial solar illumination. The plausible causes behind the enhanced H-2 evolution are discussed in detail.