Environment friendly and remarkably efficient photocatalytic hydrogen evolution based on metal organic framework derived hexagonal/cubic In2O3 phase-junction

The direct overall water splitting with low/non-toxicity semiconductor-based photocatalysts is regarded as a feasible but challenging method for hydrogen production. Herein, we firstly propose the feasily obtained rhombohedral corundum/cubic In2O3 (rh/c-In2O3) phase-junction by direct annealing metal organic framework (MIL-68(In)-NH2) in air atmosphere. The spectroscopic characterization and photo-electrochemistry test indicate that this special phase-junction could effectively accelerate the separation and transfer of photogenerated charges between rh-In2O3 and c-In2O3. The optimal In2O3 phase-junction shows hydrogen production rate of 2244 mu mol h(-1) g(-1) in 15 vol % triethanolamine aqueous solution, corresponding to the apparent quantum yields of 35 % at 400 nm, is approximately 12 times higher than that of bare c-In2O3. The results of vitro cytotoxicity assay and cellular reactive oxygen species (ROS) generation suggest that In2O3 samples are safety photocatalysts to environment and human being. The Density Functional Theory (DFT) calculations and experiment results manifest the photo-induced electron transfer from c-In2O3 to rh-In2O3 with a Z-scheme mechanism. This work not only reports a novel Z-scheme phase-junction photocatalysts but also provides an idea for the design of environmentally friendly photocatalysts for water splitting hydrogen production.

Automated summary

A novel rhombohedral corundum/cubic In2O3 (rh/c-In2O3) phase-junction is proposed through direct annealing of a metal organic framework, demonstrating enhanced separation and transfer of photogenerated charges and increased hydrogen production rate. Moreover, the In2O3 samples are shown to be safe for the environment and human beings, and the study provides insights for the design of environmentally friendly photocatalysts for water splitting hydrogen production.