S-scheme Cs2AgBiBr6/Ag3PO4 heterojunction with efficient photocatalysis performance for H2 production and organic pollutant degradation under visible light

[Display omitted] •S-scheme heterojunction strategies enhance dual-function photocatalysis activity.•Nano-flower structure is good for a strong interface and high crystalline quality.•The predicted reaction sites on TC molecules are calculated by CDFT.•The calculation methods explain the TC mineralization pathway and reaction mechanism. A dual-function S-scheme Cs2AgBiBr6/Ag3PO4 (CA) heterojunction photocatalyst with nano-flower structure was synthesized to achieve green energy hydrogen (H2) production and persistent organic pollutants degradation under visible light. The high crystalline quality and strong interface of CA enhanced the photocatalysis performance. Specifically, the photodegradation efficiency of tetracycline hydrochloride (TC) reached to 92.43 % in 60 min. And the yield of photocatalytic H2 evolution (PHE) accumulated about 4915.4 μmol/g within 6 h. The effects of initial pH, catalysts dosage, initial TC concentration and various sacrificial agents were investigated. It was found that the photocatalytic performance of CA for TC degradation and PHE was mainly affected by pH and various sacrificial agents. The TC degradation efficiency and PHE yield remained at 89.3 % and 3798.12 μmol/g in the fifth time photocatalytic cycle experiment, showing a high photostability of CA. Additionally, the photodegradation kinetics of TC was fitted well the pseudo-first-order mode and the rate constant k (0.0931 min−1) proved fast photodegradation rate. The analysis of the charge transfer mechanism and density functional theory calculation revealed that more photoinduced active species (holes, ·O2- and ·OH) were inspired and attacked nucleophilic and radical reaction sites on TC molecules. Furthermore, the emerging intermediates were detected by LC-MS, and the three possible degradation pathways of TC were proposed.