In-Situ Hydroxyl Modification of Monolayer Black Phosphorus for Stable Photocatalytic Carbon Dioxide Conversion

Abstract Black phosphorus (BP) is one of the most attracting materials that has been the subject of a theoretically predicted on photocatalytic CO2 reduction reactions. However, due to the limited stability, it has not been reported as a main catalyst in the photocatalytic reduction of CO2. For the first time, we have successfully demonstrated that an excellent stable monolayer BP with hydroxyl modification (M-BP-OH) can be in-situ obtained via a green exfoliation method assisted by liquid nitrogen, and used as photocatalysts for CO2 reduction. The hydroxy functional groups could occupy the lonely pair electrons site, inhibiting the reaction between this lonely pair electrons and oxygen to finally form stable monolayer BP. The as-prepared M-BP-OH showed a visible light active photocatalytic CO production rate of 112.6 μmol h−1 g−1, which was 4 times higher than that of bulk BP (25.3 μmol h−1 g−1). Moreover, the M-BP-OH survived with the stringent humid air (90 % humidity, 24 h), ambient conditions (30 days) and cycling tests (300 W Xe lamp, 60 h). Metal-free BP as a main catalyst, has high potential in photocatalytic CO2 reduction demonstrated by the combined characteristics of high stability, high performance and low cost.