Constructing interfacial electric field and Zn vacancy modulated ohmic junctions ZnS/NiS for photocatalytic H2 evolution

Abstract

Adjusting the interfacial transport efficiency of photogenerated electrons and the free energy of hydrogen adsorption through interface engineering is an effective means of improving the photocatalytic activity of semiconductor photocatalysts. Herein, hollow ZnS/NiS nanocages with ohmic contacts containing Zn vacancy (VZn-ZnS/NiS) are synthesized using ZIF-8 as templates. An internal electric field is constructed by Fermi level flattening to form ohmic contacts, which increase donor density and accelerate electron transport at the VZn-ZnS/NiS interface. The experimental and DFT results show that the tight interface and VZn can rearrange electrons, resulting in a higher charge density at the interface, and optimizing the Gibbs free energy of hydrogen adsorption. The optimal hydrogen production activity of VZn-ZnS/NiS is 10,636 μmol h−1 g−1, which is 31.9 times that of VZn-ZnS. This study provides an idea for constructing sulfide heterojunctions with ohmic contacts and defects to achieve efficient photocatalytic hydrogen production.

Keywords

• Zn vacancy
• Ohmic contact
• Donor density
• Hollow nanocages
• Photocatalytic H2 production