Prussian blue analogue in situ derived hierarchical flower-like ZnS/FeS2 Z-scheme heterojunction for boosted visible-light responsive photocatalytic degradation of Rhodamine B with synergistic peroxydisulfate activation

Abstract

A micro/nano hierarchical flower-like ZnS/FeS₂ direct Z-scheme heterojunction visible-light catalyst was in situ derived from a Prussian blue analogue cube (Zn–Fe PBA) using a facile one-pot hydrothermal sulfidation strategy. The as-prepared ZnS/FeS₂ catalyst shows extraordinarily boosted visible-light photocatalytic degradability for Rhodamine B (RhB) with the synergism of peroxydisulfate (PDS). Under visible-light illumination, 98.5% degradation efficiency can be achieved within 15 min and 100% within 20 min with excellent structural stability of ZnS/FeS₂. The degradation kinetic constant of ZnS/FeS₂ + PDS is 9.33 times that of ZnS/FeS₂, 23.02 times that of p-ZnS/FeS₂, 24.05 times that of FeS₂, and 28.25 times that of ZnS, respectively. The ZnS/FeS₂ heterojunction shows significant synergistic benefits in the photocatalytic degradation reaction. More advantageously, ZnS/FeS₂ + PDS shows excellent photocatalytic degradation performance in a wide pH range (1–10). A reasonable direct Z-scheme heterojunction mechanism for visible-light responsive photocatalytic degradation of RhB with ˙OH, h⁺, ˙O₂⁻, and ˙SO₄⁻ as the crucial active species is recommended for the ZnS/FeS₂ + PDS composite system. The micro/nano hierarchical flower-like structure of ZnS/FeS₂ simultaneously combines the high activity of nano-materials with the advantages of easy recycling of micro-sized materials. The in situ transformation characteristics of ZnS/FeS₂ from the PBA template contribute to the advantageous high performance and structural stability.