Abstract: High photogenerated carrier recombination rate and weak spectral response are the two main factors restricting photocatalytic activities of photocatalysts. In this work, a novel Ag/Bi₂₄O₃₁Cl₁₀ heterojunction has been developed by the in-situ photoreduction technique to address the preceding issues. Physicochemical properties of as-synthesized 0.7 wt% Ag/Bi₂₄O₃₁Cl₁₀ photocatalysts were investigated in detail. The Ag clusters can be seen as surface plasmon polaritons to light absorption capacity and photothermal effect, which was demonstrated via Raman and UV-Vis diffuse reflectance spectra (UV-Vis DRS). Density functional theory (DFT) calculations show that the additional unoccupied crystal orbital by the silver (Ag) will accelerate the charge separation where some of the excited electrons to the conduction band of Bi₂₄O₃₁Cl₁₀ will drift to these orbitals which in turn prevent charge recombination. Therefore, Ag metal cluster-decorated Bi₂₄O₃₁Cl₁₀ photocatalysts can be identified as electron trappers to boost the spatial separation of the photogenerated carrier, and finally, the CH₄ generation rate and the rhodamine b (RhB) degraded efficiency of Ag/Bi₂₄O₃₁Cl₁₀ photocatalysts are enhanced about 1.54 and 5.20 times, respectively. The Ag/Bi₂₄O₃₁Cl₁₀ composite photocatalyst retained high photocatalytic activities after four cycles indicating the stability and repeatability of the Ag/Bi₂₄O₃₁Cl₁₀ composite. This work aims to provide new insight into modifying ideal semiconductor materials for high photocatalytic activity.

Key words: Photocatalyst, Bi₂₄O₃₁Cl₁₀, Ag clusters, Surface plasmon polariton, Electron trapper