Boron containing metal–organic framework for highly selective photocatalytic production of H2O2 by promoting two-electron O2 reduction

Abstract

A zirconium-based metal–organic framework containing boron (UiO-66-B) is prepared, which displays efficient photocatalytic H₂O₂ production. The H₂O₂ evolution rate is about 1002 μmol g⁻¹ h⁻¹, much higher than that of most known photocatalysts. Pristine UiO-66 displays a much lower activity (314 μmol g⁻¹ h⁻¹) under the same conditions, suggesting the significant role of boron. Both theoretical calculations and the combined experimental results verify the above conclusion, and the role of boron is ascribed to the following aspects: (1) enhanced O₂ adsorption, (2) highly selective proton-coupled two-electron transfer, (3) faster carrier separation and surface charge transfer, and (4) faster generation but slower decomposition rates of H₂O₂. This work highlights key factors in the two-electron O₂ reduction reaction (ORR), presents a deeper understanding of the role of boron in enhancing H₂O₂ production, and provides a new strategy for designing photocatalysts with excellent H₂O₂ evolution efficiency.