Boron containing metal-organic framework for highly selective photocatalytic production of HO by promoting two-electron O reduction.

A zirconium-based metal-organic framework containing boron (UiO-66-B) is prepared, which displays efficient photocatalytic HO production. The HO evolution rate is about 1002 μmol g h, much higher than that of most known photocatalysts. Pristine UiO-66 displays a much lower activity (314 μmol g h) 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 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 HO. This work highlights key factors in the two-electron O reduction reaction (ORR), presents a deeper understanding of the role of boron in enhancing HO production, and provides a new strategy for designing photocatalysts with excellent HO evolution efficiency.