Synergy of heterojunction and interfacial strain for boosting photocatalytic H evolution of black phosphorus nanosheets.

As an emerging post-graphene two-dimensional material, black phosphorus (BP) has attracted enormous interest as a promising cocatalyst for photocatalytic hydrogen (H) evolution, however, the activity of either pristine bulk or BP nanosheets is far from satisfactory. Herein, we present an effective strategy to greatly boost the H evolution performance of BP via applying the synergistic effect of heterojunction and interfacial lattice strain. A multilayered heterostructure coupling BP nanosheets and nickel oxide (NiO) nanosheets with abundant interface P-Ni and PO bonds is synthesized and utilized as a proof-of-concept material for our design. Both the experimental and theoretical results have revealed that the strain is formed in BP-NiO multilayered heterostructure. The generated lattice strain induces the charge redistribution at the interface between BP and NiO, which leads to the improved electron transfer efficiency and favorable H* adsorption kinetics for photocatalytic H evolution reaction. As a result, the BP-NiO heterostructure with strain effect exhibits much enhanced photocatalytic H evolution activity in the presence of Eosin Y (EY) as photosensitizer, exceeding that of zero-strained BP/NiO heterostructure and many other reported noble-metal-free cocatalyst.