Photocatalytic oxidation of p-xylene coupled with hydrogen evolution over MOFs-based bifunctional catalyst

Photocatalytic oxidation of organic small molecules accompanied by the release of hydrogen is considered to be a dual optimal route to obtain green energy and high value-added oxidation products through a green way. A TiO2-CdS/Ni bi-functional catalyst combining the advantages of MOFs, semiconductor materials and metal nano -particles was prepared by using MIL-125 as a precursor. The prepared composite catalyst has strong photo -responsiveness, abundant catalytic sites and the ability to oxidize aromatic compounds. The hydrogen evolution capacity can reach 6.6 mmol center dot g-1 center dot h-1 over TiO2-CdS/Ni in the presence of hole sacrificial agent. The hydrogen production was 81.9 mu mol center dot g-1 h-1 in the system with PX instead of hole sacrificial agent, and 521.2 mu mol center dot g-1 of TALD oxidation products can be obtained with high selectivity. The high activity of the catalytic system can also be extended to the oxidation of toluene and benzyl alcohol, which can generate hydrogen of 33.3 mu mol center dot g- 1 center dot h-1 and 1.6 mmol center dot g-1 center dot h-1, and 620.3 mu mol center dot g-1 and 4.2 mmol center dot g-1 of benzaldehyde were produced at the same time, respectively. This study successfully extends the strategy of photocatalytic oxidation of organic small molecule coupled with hydrogen evolution to PX and other compounds.