Fig. 1. (Color online) Schematic illustration and TEM images of the product evolution from Cu_1.94S NCs to different types of heterostructured and alloyed NCs^[53].

Fig. 2. TEM images and morphology diagrams of 1D, quasi-2D and 2D CuGaS₂ NCs^[64].

Fig. 3. (a) TEM images and (b) STEM-EDS elemental mapping images of the L-shaped Cu–Ga–Zn–S NCs. (c) XRD patterns of the products obtained at different reaction time. (d–h) TEM images of wurtzite Cu–Ga–Zn–S NCs synthesized at 240 °C for different reaction time: (d) 7 min, (e) 23 min, (f) 45 min, (g) 60 min, and (h) 120 min^[66].

Fig. 4. (Color online) (a) The hydrogen production rate of the Cu_1.94S NCs, CuInS₂ and CuGaS₂ alloyed NCs. (b) The hydrogen production rate of Cu_1.94S NCs, Cu_1.94S–ZnS, Cu_1.94S–CdS and Cu_1.94S–MnS heterostructured NCs. (c) The energy level diagram of Cu_1.94S NCs (black), CuInS₂ alloyed NCs (red), CuGaS₂ alloyed NCs (blue), Cu_1.94S–ZnS (pink), Cu_1.94S–CdS (green) and Cu_1.94S–MnS heterostructured NCs (orange)^[53].

Fig. 5. (Color online) (a) The energy level diagrams of 1D, quasi-2D and 2D CuGaS₂ NCs. (b) The photocatalytic hydrogen production rates of 1D, quasi-2D and 2D CuGaS₂NCs.

Fig. 6. (Color online) Schematic models of the (a) (001) surface and (b) (100) surface of stimulated wurtzite CuGaS₂ after geometry optimization. Work function for the (c) CuGaS₂ (001) surface and (d) (100) surface. The calculated PDOS for (e) CuGaS₂ (001) and (f) (100) surfaces, where the PDOS contains the total layer surface, top layer surface and bottom layer surface for simulated every surface^[64].

Fig. 7. Photocatalytic hydrogen evolution of binary Cu₃₁S₁₆NCs, ternary CuGaS₂ NCs and quaternary L-shaped Cu–Ga–Zn–S nanorods^[66].

Fig. 8. (Color online) Cycling tests of hydrogen production for (a) Cu_1.94S–CdS (red) and Cu_1.94S (black) NCs and (b) L-shaped Cu–Ga–Zn–S nanorods under simulated solar illumination^[66].