Phase engineering of CdS optimized by BP with p-n junction: Establishing spatial-gradient charges transmission mode toward efficient photocatalytic water reduction

As one of appealing storage patterns of solar energy, the efficient photocatalytic hydrogen evolution from water splitting has great potentiality in sustainable development for renewable energy, but it still suffers the low conversion level due to sluggish spatial behavior of photocarriers. Herein, on the basis of phase engineering theory, a novel conceptual design of energy band-gradient distribution is presented to consolidate the spatial transportation continuity of photocarriers, which is realized in the phase junction of CdS for the first time. Further being integrated with black phosphorus (BP) nanodots, the utilization of incident photons is extended to cover broad solar light-responsive window, and the p-n junctions with powerful internal electric fields resemble many accelerators distributed on the energy band-gradient pathway, thus furnishing sufficient internal dynamical transfer force for separation and migration of photocarriers with prolonged lifetime. The peculiar compound photocatalyst exhibits an excellent hydrogen evolution activity of 163.65 μmol·h−1·g−1 and 5.72 mmol·h−1·g−1, as well as high apparent quantum yields (0.73 % and 25.7 % at 420 nm) under different conditions (with or without sacrificial agents). This study proposes a new exploitation strategy for the manipulation of energy band-gradient configuration in designing superior photocatalytic systems with available solar conversion efficiency.