Enhanced oxidation ability in SnO2/Pt-B-g-C3N4 towards 2,4-dichlorophenol removal.

Heterostructure type and valence band (VB) and conductor band (CB) potential governs the redox ability of photocatalysts, in which enhanced oxidation is a key for phenol degradation. To increase the photocatalytic oxidation ability of catalysts, broad band gap SnO2 was grown on Pt-decorated superior thin B-doped g-C3N4 (BCN) nanosheets for 2,4-dichlorophenol (2,4-DCP) removal. B-doped g-C3N4 nanosheets were created by a two-step thermal polymerization. Small Pt nanoparticles were grown on B-g-C3N4 nanosheets, in which B-doping resulted in the homogeneous distribution of Pt nanoparticles of 2-3 nm. These small Pt nanoparticles further supported the deposition of SnO2 nanoparticles with small sizes of 4-7 nm and narrow distribution by solvothermal synthesis to create SnO2/Pt/B-g-C3N4 heterostructures with well-developed interface and homogeneous component distribution. The much positive VB of SnO2 improved the oxidation of photogenerated holes. These heterostructure catalysts revealed a 2,4-DCP t removal rate of 90.5 % at a concentration of 70 mg/L. The removal efficiency of 2,4-DCP was further increased in peroxydisulfate (PDS) system, and 2,4-DCP of 98 % was finally degraded. The well charge carrier transfer ability of SnO2 and Z-scheme heterostructure formation with fine Pt nanoparticles decreased the photogenerated charge carrier recombination. The photocatalytic mechanism and degradation procedure of 2,4-DCP in PDS system were systemically discussed. The oxygen vacancies in SnO2 components allow accelerated charge carrier transfer and promote the degradation of the pollutants. These results supply a utilizable way for improving the redox ability of catalysts and the application in pollution degradation in low-cost PDS-activated systems.