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

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 mu mol g(-1) h(-1), much higher than that of most known photocatalysts. Pristine UiO-66 displays a much lower activity (314 mu mol 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 O-2 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 O-2 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.