In situ synthesis of TiO2@NH2-MIL-125 composites for use in combined adsorption and photocatalytic degradation of formaldehyde

TiO2@NH2-MIL-125, composite photocatalysts with close interfacial contact between NH2-MIL-125 and TiO2, were successfully synthesized via an in-situ solvothermal method for formaldehyde (HCHO) removal under UV irradiation. Samples were characterized by using a variety of analytical techniques. The results showed that TiO2 particles were highly dispersed on the surface of NH2-MIL-125, and there was a strong electronic interaction (Ti-N-C) between elements of the composite. TiO2@NH2-MIL-125 exhibited significantly enhanced photocatalytic performance for HCHO removal compared to pure TiO2 and NH2-MIL-125 that was ascribed to the synergistic combination of high adsorption capacity of NH2-MIL-125, high dispersion of TiO2 and efficient interfacial charge transfer between TiO2 and NH2-MIL-125. Furthermore, the HCHO removal rate over the composite remained at 90% after 122 h of continuous photocatalytic reaction, indicating the high stability of the catalyst. This work provides new insights that will be helpful in the further development of photocatalysts for indoor air purification.