Scheme 1

Synthesis procedure of NiO/ZIS composites."

Fig 1

(a) XRD patterns of ZIS, NiO and NiO/ZIS composites. (b) SEM, (c, d) TEM and (e) HRTEM images of 2-NiO/ZIS. (f) The elemental mapping of Zn, In, S, Ni and O in 2-NiO/ZIS."

Fig 2

(a) Survey XPS spectra of ZIS, 2-NiO/ZIS and NiO, (b–d) high-resolution XPS spectra of Zn 2p, In 3d and S 2p of ZIS and 2-NiO/ZIS, (e, f) high-resolution XPS spectra of O 1s and Ni 2p of NiO and 2-NiO/ZIS."

Fig 3

(a) UV-Vis DRS spectra of ZIS, NiO/ZIS and NiO, (b) Tauc plots of ZIS and NiO, (c) Mott-Schottky curves of ZIS and NiO, (d) DMPO spin-trapping EPR spectra of DMPO-•O2– and DMPO-•OH over 2-NiO/ZIS. The possible charge transfer mechanism of (e) traditional type Ⅱ and (f) S-scheme heterojunction over 2-NiO/ZIS."

Fig 4

(a–d) In situ irradiated XPS spectra of Zn 2p, In 3d, S 2p and Ni 2p for 2-NiO/ZIS, (e) TAS dynamics of ZIS under 350 nm irradiation fitted by two-exponential, and (f) TAS dynamics of 2-NiO/ZIS under 350 nm irradiation fitted by three-exponential functions."

Fig 5

(a) EIS (inset illustrates the equivalent circuit model used to fit the experimental data, where Rs represents total series resistance of the system, Ri corresponds to the internal resistance of the electrode combined with a constant phase element (CPEbulk, trap), and Rct signifies the charge transfer resistance from the surface states to the solution with the corresponding CPEs), (b) TPR, (c) SPV, (d) TRPL, and (e) LSV spectra of as-prepared samples. CV curves of (f) NiO, (g) ZIS, (h) 2-NiO/ZIS at different scan rates, and (i) the corresponding fitting curves between current density and scan rates."

Fig 6

(a) Time-yield plots and (b) the H2 evolution rate for ZIS, NiO/ZIS and NiO. (c) TRPL spectra of ZIS, NiO and 2-NiO/ZIS tested in deionized water. (d) The AQY of 2-NiO/ZIS at different wavelengths. (e) Comparison of AQY for 2-NiO/ZIS in this work with the reported ZIS-based photocatalysts. (f) PHE rate of 2-NiO/ZIS in the presence of different water sources, and (g) TRPL spectra of 2-NiO/ZIS tested in different water sources. (h) PHE rate of 2-NiO/ZIS in the presence of different salts, and (i) the average fluorescence lifetimes of 2-NiO/ZIS in different salt solutions."

Fig 7

(a, b) Calculated band structure of ZIS and NiO, (c, d) the work functions of ZIS and NiO calculated by DFT technique, (e) the optimized H adsorption configuration and corresponding adsorption energy at the heterojunction interface of NiO/ZIS, (f) the optimized H adsorption configuration and associated adsorption energy on the NiO surface within NiO/ZIS, (g) the H adsorption energy of ZIS, NiO/ZIS and NiO, (h) the charge transfer mechanism over NiO/ZIS heterojunction."