Hierarchical Cds/Ni3s4/Ni2p@C Photocatalyst for Efficient H2 Evolution Under Visible Light Irradiation

Abstract

The structural and morphology modulations of semiconductors play a crucial role in effective charge separation and improvement of photocatalytic performance under visible light. In this paper, a novel CdS/Ni3S4/Ni2P@C heterojunction was constructed and applied to visible-light-driven photocatalytic water splitting to generate H2. The binary Ni3S4/Ni2P co-catalyst encapsulated in carbon substrate was prepared by sequential carbonization and phosphorization of Ni-MOF precursor. Combined characterization and photoelectrochemical measurement results reveal that the highly porous Ni3S4/Ni2P@C facilitates the assembly of CdS nanowires on its surface, thus enhancing the visible light response capability of the CdS/Ni3S4/Ni2P@C heterojunction catalyst by reducing the forbidden bandgap of CdS. The hydrogen production rate of 21.56 mmol h-1 g-1 for CdS/Ni3S4/Ni2P@C with Ni3S4/Ni2P@C mass fraction of 10 wt% was 26 times higher than that of CdS in the photolytic aquatic hydrogen system with lactic acid as the sacrificial agent. A possible mechanism for the photocatalytic enhancement of the Ni3S4/Ni2P@C co-catalyst was systematically investigated and discussed. This research opens a new strategy for synthesizing unique ternary heterojunction photocatalysts via MOF precursors.

Keywords: Ni-MOF, CdS, Ni3S4/Ni2P co-catalyst, Photocatalytic hydrogen evolution