Improving the Photocatalytic H2 Evolution of CdS by Adjusting the (002) Crystal Facet

In general, the activities for H2 evolution are dependent on the morphologies and exposed facet of semiconductor-based photocatalysts. Here, we reported that CdS with the (002) crystal facet and a small capacitance was vital for enhancing photocatalytic H2 evolution. After loading CoP as a co-catalyst, the H2 evolution activity of CoP/CdS-P (particle-like, dominant (002) facet) increased remarkably to 24 600 μmol/(h g), which was 1.28 times that of CoP/CdS-L (leaflike), 2.09 times that of CoP/CdS-R (rodlike), and 5.67 times that of CoP/CdS-S (spherelike). Electrochemical tests and surface photovoltage spectra demonstrated that CdS-P with a large proportion of the (002) facet and the smallest capacitance of 4.31 F/cm2 leads to the highest separation and transportation of photoexcited electrons. This study reveals the superiority of CdS with the (002) facet and gives an idea to design efficient semiconductor-based photocatalysts with a small capacitance.