Bottom-up approach to quasi-monolayer black phosphorus advancing photocatalytic H2 evolution

A mild bottom-up approach is developed to prepare quasi-monolayer black phosphorus (BP) from precursor red phosphorus. Linear diamine-induced “dissolution-crystallization” mechanism via polyphosphide clusters is proposed to account for the phosphorus phase transition in solution. For the first time, the application of quasi-monolayer BPs in photocatalytic H2 evolution is demonstrated. Particularly, ethylenediamine-intercalated quasi-monolayer BP (eda-BP) exhibits 57.2-folds enhancement in photocatalytic H2 evolution activity than pure BP. The greatly improved photocatalytic performance is ascribed to the optimized bandgap with stronger redox capacity and significantly suppressed photogenerated charges recombination due to strong electron transfer from eda to BP layers. Additionally, the unique intercalation structure endows the quasi-monolayer eda-BP with improved stability. This bottom-up intercalation strategy provides a new opportunity to advance the photocatalytic H2 evolution activity of BP and offers extendable availability for other 2D photocatalyst materials.