Regulating Deep and Shallow Defects of CuInS2 Quantum Dots To Enhance Photocatalytic Hydrogen Production

The effective capture and transmission of charge carriers are the key to improving their conversion of solar energy into hydrogen. The utilization of a photon-generated carrier by increasing the active site has attracted much interest. Recently, quantum dot materials located within nanospecifications with a high specific surface area are expected to provide a large number of active sites and are confirmed as promising photocatalysts. However, the high recombination rate of photogenerated electrons resulting in the small number of effective photogenerated electrons used for photocatalytic hydrogen production limits their further application. The high recombination rate of photogenerated electron holes in conventional quantum dots leads to a large reduction in the number of effective photogenerated electrons involved in the photocatalytic hydrogen production process, limiting their further application. Here, water-soluble “nonclassical” CuInS2 quantum dots (CIS QDs) with rich surface defects are prepared by the interface nucleation mechanism. The proportion of deep defects and shallow defects is controlled by partial coating shell and heating, and the photocatalytic hydrogen production performance is effectively improved. Under this strategy, using Ni(OH)2 as a cocatalyst and ascorbic acid as a sacrificial agent to consume excess holes, “nonclassical” CIS/ZnS QDs exhibit a photocatalytic hydrogen production rate of 35.6 mmol·g–1·h–1, which is ∼240 times that of traditional CIS QDs. Moreover, the strategy of regulating deep and shallow defects can provide an efficient path to improve carrier separation efficiency and will help in the development of highly efficient photocatalysts.