Tailoring high-index-facet and oxygen defect of black In2O3_x/In2O3 as highly photothermal catalyst for boosting photocatalytic hydrogen evolution and contaminant degradation

Defect engineering and the high index surface (HIF) can be regarded as two effective methods to tuning the microstructure of catalysts and photocatalytic activities. So far, the integration of the synergistic effects of ox-ygen vacancies and HIF advantages into semiconductors to enhance photocatalytic performance has received little attention. Herein, Black In2O3_x/In2O3 with oxygen vacancy and exposed (321) surface active crystal plane has been synthesized as excellent photocatalysts via a facile method. The catalysts of Black In2O3_x/In2O3 can reach the highest photocatalytic hydrogen evolution rate (1046 mu mol h_ 1 g_ 1) and degradation efficiency of MB (0.017 min_1) with 120 min, respectively. As a special phase junction, Black In2O3_x/In2O3 could effectively boost the separation and transfer of photogenerated charges because of unique defect homojunction micro-structure resulting in exposing abundant photocatalyst redox active sites. The experiment characterization and density functional theory (DFT) calculations can further employ to unveil mechanism of enhanced hydrogen evolution reaction (HER) activity. It is obvious that enhanced HER activity was attributed to synergy of oxygen defect and exposed (321) surface active crystal planes due to electron distribution and lower Gibbs free energy of H adsorption. This work might open up new avenues to integrate exposed facets and oxygen vacancy for enhancing the photocatalytic hydrogen evolution with renewable energy sources and environmental remediation.

Automated summary

Defect engineering and high index surface are two effective methods for tuning the microstructure and photcatalytic activities of catalysts. This study focuses on integrating oxygen vacancies and high index surfaces into semiconductors to enhance photocatalytic performance. Black In2O3_x/In2O3 catalysts with oxygen vacancies and exposed (321) surface have been synthesized and exhibit excellent photocatalytic hydrogen evolution rate and degradation efficiency. The enhanced hydrogen evolution activity is attributed to the synergy of oxygen defects and exposed (321) surface active crystal planes.