Fabrication of CdS-SBA-15 nanomaterials and their photocatalytic activity for degradation of salicylic acid under visible light

CdS-SBA-15 nanomaterials were synthesized by solvothermal method using cadmium nitrate as cadmium source and thiourea as sulfur source. The properties of as-prepared materials were characterized by means of XRD, FTIR, TEM, XPS, N-2 physisorption, UV-Vis DRS and PL spectra, etc. The results show as-synthesized materials have partially ordered mesoporous structure, larger specific surface area, and higher content of CdS and good crystallinity. The combination of SBA-15 and CdS did almost no reduction in the absorption light range of CdS, but greatly increased the photocapacity of the composite. The synergistic effect of CdS and SBA-15 leads to improving the photocatalytic degradation activity of salicylic acid under visible light. When the photocatalyst was 30 mg (0.75 g/L) and the concentration of salicylic acid was 10 mg/L, the maximum degradation efficiency of salicylic acid was 84.93% after 6 h of light. Photocatalytic reaction has a lower activation energy (2.90 kJ/mol), activation enthalpy (3.13 kJ/mol) and activation entropy (-281.00 J/(mol K)). The photocatalytic mechanism study demonstrates that superoxide radicals (O-2(center dot-)) are the most key active species, e(-) and h(+) have something to do with the photocatalytic reaction, while center dot OH has little to do with the photocatalytic reaction. In sum, the protection effect of SBA-15 on CdS nanomaterials makes the composite have a higher photolumination intensity and a higher photocatalytic activity.