A porous hybrid material based on calixarene dye and TiO2 demonstrating high and stable photocatalytic performance
A highly robust hybrid material based on calixarene dye (HO-TPA) and titanium dioxide with a micro/mesoporous structure and a large surface area (denoted as HO-TPA–TiO2) has been prepared by a facile sol–gel method. When Pt nanoparticles (Pt NPs) or fac-[Re(4,4′-disphosphonic acid-2,2′-bipyridine)(CO)3Cl] (ReP) as co-catalysts are introduced onto the hybrids, respectively, the two hybrid systems can display dual-functional photocatalytic properties. Under visible-light irradiation, the optimized Pt/HO-TPA–TiO2 system exhibits high hydrogen production activity (618.3 mmol g−1 h−1 based on Pt mass) and performs with excellent stability even after being used for 15 times (a turnover number of 6417 after 75 h). On the other hand, the optimum ReP/HO-TPA–TiO2 material displays persistent photocatalysis of CO2 reduction to CO and gives a turnover number of 534 over 26 h (854.4 mmol g−1 based on ReP mass), which is one of the highest among all the reported heterogeneous catalytic systems under visible light. The high activity and stability of the HO-TPA–TiO2 based hybrid materials can be attributed to the stable coordination linkage and efficient electron transfer between HO-TPA and micro/mesoporous TiO2. The current study offers inspiration for the design and application of new multi-functional organic–inorganic hybrid systems for efficient photocatalysis.