Boosting Photocatalytic Hydrogen Peroxide Production from Oxygen and Water Using a Hafnium-Based Metal-Organic Framework with Missing-Linker Defects and Nickel Single Atoms

Metal-organic frameworks (MOFs) are one of the most promising candidates for photocatalytic hydrogen peroxide (H2O2) production from dioxygen (O2) and water. However, MOF-driven H2O2 production from O2 and water remains a challenge because MOF photocatalysts need to exhibit high structural stability in aqueous reaction systems while suppressing H2O2 decomposition. In the present study, we demonstrate that a Hf-based UiO-66-NH2 with missing-linker defects and Ni single atoms dramatically promotes the photocatalytic production of H2O2 from O2 and water under visible-light (lambda > 420 nm) irradiation. The acetate-capped missing-linker defects lead to suppression of the non radiative relaxation of organic linkers and to the prevention of H2O2 decomposition, whereas the Ni single-atom cocatalysts promote the separation of photogenerated charges and selective two-electron oxidation of water to generate H2O2. The synergetic effect of missing-linker defects and Ni single atoms dramatically improves photocatalytic H2O2 production, resulting in a 6.3-fold increase in activity compared with that of pristine Hf-UiO-66-NH2. This study provides not only new insights into defect engineering in MOF photocatalysts but also an important strategy for achieving highly selective H2O2 production via O2 reduction and water oxidation.

Automated summary

This study demonstrates the successful promotion of photocatalytic H2O2 production by introducing missing-linker defects and Ni single atoms in MOFs. The missing-linker defects suppress the non radiative relaxation of organic linkers and prevent H2O2 decomposition, while the Ni single atoms promote the separation of photogenerated charges and selective oxidation of water to generate H2O2. The synergetic effect of missing-linker defects and Ni single atoms significantly improves the photocatalytic H2O2 production activity.