Controlled fabrication of Au@NH2-MIL-125(Ti)/CdS with enhanced photocatalytic ability for the degradation of MB

The application of CdS in pollutant degradation was limited due to the rapid compounding of photogenerated carriers. A ternary Au@NH2-MIL-125(Ti)/CdS (5Au@40NMT/CdS) composite catalyst was synthesized with a two-step method and methylene blue (MB) was used as simulate contaminants to evaluate its photocatalytic performance under simulated visible light. The compounding of NH2-MIL-125 and the loading of Au nanoparticles significantly enhanced the photodegradation performance of the composite catalyst. Compared with pure CdS, the ternary composite catalyst exhibited higher degradation efficiency (93.3 %) and higher degradation rate (9 times that of CdS)within 30 min, which was attributed to the high specific surface area and the synergistic effect of the three components that accelerated the carrier separation and broadened the photoresponse range. In addition, superoxide radical (·O2-) was identified as the main active species in the MB degradation process by the electron spin resonance (ESR) technique. This work was expected to give a strategy for the fabrication and design of CdS/MOF composite catalysts in the field of pollutant degradation.