Seed-mediated growth of heterostructured CuS-MS (M = Zn, Cd, Mn) and alloyed CuNS (N = In, Ga) nanocrystals for use in structure- and composition-dependent photocatalytic hydrogen evolution.

Multinary copper-based chalcogenide nanocrystals (NCs) as light-driven photocatalysts have attracted extensive research interest due to their great potential for generating sustainable energy without causing environmental concerns. However, systematic studies on the growth mechanism and related photocatalytic activities involving different valent metal ions (either M or N) as foreign cations and monoclinic CuS NCs as the 'parent lattice' have rarely been carried out. In this work, we report an effective seed-mediated method for the synthesis of heterostructured CuS-MS NCs (M = Zn, Cd and Mn) and alloyed CuNS NCs (N = In and Ga). A typical cation exchange process took place prior to the growth of heterostructured NCs, while further inter-cation diffusion occurred only for the alloyed NCs. When compared with CuS NCs, all the heterostructured CuS-MS NCs and CuGaS NCs showed enhanced photocatalytic activities toward hydrogen production by water splitting, owing to their tailored optical band gaps and energy level alignments. Although optically favored, CuInS ANCs were not comparable to others due to their low conduction band minimum for the reduction of HO to H.