Preparation of a novel Z-scheme AgI/Ag/Bi₂₄O₃₁Cl₁₀ catalyst with enhanced photocatalytic performance via an Ag⁰ electron transfer intermediate

In this work, a novel Z-scheme AgI/Ag/Bi₂₄O₃₁Cl₁₀ photocatalyst was prepared by molecular calcination followed a precipitation–photoreduction process. AgI/Ag/Bi₂₄O₃₁Cl₁₀ combines the advantages of a heterojunction with noble metal deposition. The crystalline phase, morphology, optical and photo-electrochemical properties of the prepared AgI/Ag/Bi₂₄O₃₁Cl₁₀ composites have been determined. The photocatalytic activity of AgI/Ag/Bi₂₄O₃₁Cl₁₀ composites was evaluated by degrading methyl orange (MO) and phenol under visible light irradiation. A mass ratio of 8% AgI in the composite was found to be optimal for the efficient degradation of MO and phenol. This was shown to degrade 84.3% of the methyl orange and 55.1% of the phenol introduced after irradiation with visible light for 2 and 4 h, respectively. Futhermore this composite is highly stable and retains excellent activity after four reaction cycles. A mechanism for the photocatalytic activity of the AgI/Ag/Bi₂₄O₃₁Cl₁₀ composite has been proposed via band structure and trapping experiments. Metallic Ag⁰ acts as an important electron transfer intermediate between Bi₂₄O₃₁Cl₁₀ and AgI. This work extends on the study of Z-scheme modifications for Bi₂₄O₃₁Cl₁₀.