Defect-engineered Zr-MOFs with enhanced O2 adsorption and activation for photocatalytic H2O2 synthesis

Defect engineering has recently received much attention as an effective approach for improving photocatalytic performances. Herein, UiO-66-NH2 with missing ligand defects (DUiO-66-NH2) wrapped by ZnIn2S4 was investigated for photocatalytic H2O2 production under visible light. The defects in DUiO-66-NH2 enable efficient charge separation and O-2 capture, which are the key factors in accelerating H2O2 production. Specifically, the O-2 adsorption capacity over ZnIn2S4/DUiO-66-NH2 was improved by a factor of 3.1 as compared to its counterpart without defects. As a result, in ambient air and pure water without any sacrificial agents, the H2O2 yield of ZnIn2S4/DUiO-66-NH2 was 340 mu mol L-1, which was significantly higher than that of ZnIn2S4/UiO-66-NH2 (150 mu mol L-1). The main H2O2 formation pathway over ZnIn2S4/DUiO-66-NH2 is an indirect oxygen reduction reaction with O-2(-) as the intermediate, and the defects in UiO-66-NH2 could act as active sites to adsorb and activate O-2 to produce O-2(-). However, the H2O2 generation over ZnIn2S4/UiO-66-NH2 undergoes both indirect and direct oxygen reduction reactions. This work could provide new insights and inspire further research into defect engineering of MOFs and photocatalytic H2O2 synthesis.

Automated summary

Defect engineering has been shown to improve the photocatalytic performance. This study investigated the use of defect-rich UiO-66-NH2 wrapped by ZnIn2S4 as a catalyst for photocatalytic H2O2 production. The defects in UiO-66-NH2 enhanced O-2 adsorption and charge separation, leading to higher H2O2 yield. The insights from this work can advance the research in defect engineering of MOFs and photocatalytic H2O2 synthesis.