Constructing hollow porous Pd/H-TiO2 photocatalyst for highly selective photocatalytic oxidation of methane to methanol with O2

The partial oxidation of methane to methanol with O2 is an attractive catalytic reaction, but the catalysts still face great challenges in terms of activity and selective oxidation, especially how to avoid overoxidation. Herein, Pd/ H-TiO2 with a unique hollow porous nanocage structure was prepared for selective photooxidation of methane into methanol by O2 under mild conditions. The as-obtained Pd/H-TiO2 exhibited a high methanol production rate of 4.5 mmol/g/h with selectivity reaching up to 70 % under optimized conditions, exceeding most reported values. The mechanism study indicated that center dot OH radicals, produced by photogenerated holes, played an important role in the activation of methane into center dot CH3 species, and the latter was further oxidized into methanol by center dot O2-radicals formed by photogenerated electrons. The strong metal-support interaction and unique porous hollow structure also effectively enhanced the catalytic activity. These new insights provide us guidance for the design of high-performance photocatalysts for selective photocatalytic oxidation of methane.

Automated summary

In this study, a unique hollow porous nanocage structure was prepared for Pd/ H-TiO2 catalysts to selectively convert methane into methanol under mild conditions with the reaction of O2. The obtained Pd/H-TiO2 exhibited a high methanol production rate of 4.5 mmol/g/h with a selectivity of up to 70% under optimized conditions, surpassing most reported values. The mechanism study revealed the significant role of ˙OH radicals produced by photogenerated holes in the activation of methane into ˙CH3 species, which were further oxidized into methanol by ˙O2 radicals formed by photogenerated electrons. The strong metal-support interaction and unique porous hollow structure effectively enhanced the catalytic activity. These findings provide guidance for the design of high-performance photocatalysts for the selective photocatalytic oxidation of methane.