Improved Charge Separation and Effective H2 Production at Interface of Crystallized Ni(OH)2–SO4–Zn4(OH)6 Junction Derived from Chemically Bonded 2D–2D ZnO–NiS Nanopanel

In this research, NiS was incorporated as a supplementary light-absorbing component to enhance the primary ZnO photocatalyst. The two components were linked through chemical means and their crystal structures, optical properties, degree of defects, and catalytic activities were explored. During a hydrothermal treatment, both Ni and S sources were simultaneously added to the ZnO particles. The resulting ZnO–NiS junction exhibited a 2D–2D structure and a crystallized junction interface capable of absorbing light in the visible region. The crystalline Ni(OH) 2 –SO 4 –Zn 4 (OH) 6 junction interface provides a large surface area and induces fast charge transfer and slow exciton recombination. This is similar to an electron transport medium between the two components. The quantum efficiency of individual NiS is close to zero; NiS acts as a light absorption aid for ZnO, facilitating the transfer of excited electrons to the ZnO conduction band, thereby enhancing the photoactivity. Hydrogen production via water splitting on the optimized 1ZnO–1NiS junction catalyst was 452.8 µmol g −1 h −1 , which is 205 and 99 times higher than that produced using the pure NiS and ZnO catalysts, respectively. Charge transfer in the ZnO–NiS junction followed a typical Type II pattern. The crystallized junction interface resulting from chemical bonding of the two particles serves as a charge carrier, affording enhanced photoactivity. Graphical abstract