A dual-functional catalyst: wood-templated BiVO₄-CdS for wood dye wastewater

A large quantity of wastewater is released from wood processing, posing a serious pollution problem to the natural environment. Photocatalysis has become a reliable method for effluent purification. In this paper, balsa-templated BiVO₄-CdS (BBC) was synthesized by impregnation calcination and chemical deposition using wood residue as a template. Rhodamine B (RhB) is used as a wood colorant and is present in wood processing wastewater. The performance of BBC in photocatalytic degradation with simultaneous hydrogen production was identified using RhB as simulated wood dye wastewater and a sacrificial electron donor. Compared to the BiVO₄-CdS without a template, the BBC exhibited higher photocatalytic degradation performance (98.32%), which was attributed to the laminar porous structure of the wood being replicated. Because of the existence of a porous structure, BBC has better adsorption properties, which accelerated photodegradation and the production process of H₂. Furthermore, surface modification with CdS nanoparticles formed Z-scheme heterojunctions, which greatly inhibited the photogenerated electron-hole compounds. When RhB provided electrons to BiVO₄ and CdS, it was also removed by the oxidation of h⁺ and ·OH, which were simultaneously generated by balsa-templated BiVO₄-CdS. BBC produced hydrogen at a higher rate (61.2 μmol g^-1 h^-1), realizing dual-functional photocatalysis. Therefore, the results support further development of dual-functional catalysts by the use of wood residues.