In the present work, we described the synthesis and characterization of the ternary Cu2O/CuS/ZnS nanocomposite using a facile two-step wet chemical method for blue LED-light-induced photocatalytic hydrogen production. The concentrations of the ZnS precursor and reaction time were essential in controlling the photocatalytic hydrogen production efficiency of the Cu2O/CuS/ZnS nanocomposite under blue LED light irradiation. The optimized Cu2O/CuS/ZnS nanocomposite exhibited a maximum photocatalytic hydrogen evolution rate of 1109 µmolh−1g−1, which was remarkably higher than Cu2O nanostructures. Through the cycle stability it can be observed that the hydrogen production rate of the Cu2O/CuS/ZnS nanocomposite decreased after 4 cycles (1 cycle = 3 h), but it remained at 82.2% of the initial performance under blue LED light irradiation. These reasons are mainly attributed to the introduction of CuS and ZnS to construct a rationally coupled reaction system, which enables the synergistic utilization of photogenerated carriers and the increased absorption of visible light for boosting blue LED-light-driven photocatalytic hydrogen evolution.

The Au@CdS nanocomposites have been synthesized using a combination of wet chemical and hydrothermal approaches at lower reaction temperatures. The concentrations of CdS precursors and reaction temperature can be essential in influencing photocatalytic water splitting under blue-LED light excitation. The optimized Au@CdS nanocomposites (5 mM CdS precursors and 100 °C) exhibited the highest hydrogen evolution rate of 1.041 mmolh−1 g−1, which is 175.3 times higher than CdS nanoparticles for de-ionized water under blue-LED light excitation. This result is ascribed to separate photogenerated charge carriers and increased light absorption by the Au core. The Au@CdS nanocomposites (1.204 mmolh−1 g−1) revealed significant applications in photocatalytic tap water splitting under blue-LED light excitation, which is 512.3 times higher than CdS nanoparticles. In addition, reusability experiments demonstrate that Au@CdS nanocomposites exhibit excellent stability for the long-term photocatalytic tap water splitting process. Furthermore, this research shows that Au nanoparticles decorated with CdS shells effectively achieve high-efficiency conversion from light to hydrogen energy.

In this study, a facile and rapid microwave-assisted synthesis method was used to synthesize In2S3 nanosheets, ZnS nanosheets, and ZnIn2S4 nanosheets with sulfur vacancies. The two-dimensional semiconductor photocatalysts of ZnIn2S4 nanosheets were characterized by XRD, FESEM, BET, TEM, XPS, UV–vis diffuse reflectance, and PL spectroscopy. The ZnIn2S4 with sulfur vacancies exhibited an evident energy bandgap value of 2.82 eV, as determined by UV–visible diffuse reflectance spectroscopy, and its energy band diagram was obtained through the combination of XPS and energy bandgap values. ZnIn2S4 nanosheets exhibited about 33.3 and 16.6 times higher photocatalytic hydrogen production than In2S3 nanosheets and ZnS nanosheets, respectively, under visible-light irradiation. Various factors, including materials, sacrificial reagents, and pH values, were used to evaluate the influence of ZnIn2S4 nanosheets on photocatalytic hydrogen production. In addition, the ZnIn2S4 nanosheets revealed the highest photocatalytic hydrogen production from seawater, which was about 209.4 and 106.7 times higher than that of In2S3 nanosheets and ZnS nanosheets, respectively. The presence of sulfur vacancies in ZnIn2S4 nanosheets offers promising opportunities for developing highly efficient and stable photocatalysts for photocatalytic hydrogen production from seawater under visible-light irradiation.

The g-C3N4@ZnIn2S4 heterostructures were successfully synthesized through a combination of thermal annealing and hydrothermal methods. To enhance the photocatalytic hydrogen production performance and explore the interface between charge carriers, heterostructures of g-C3N4@ZnIn2S4 were fabricated using varying weights of g-C3N4 nanostructures under visible light irradiation. Remarkably, the photocatalytic hydrogen production efficiency of g-C3N4@ZnIn2S4 heterostructures with 0.01 g g-C3N4 nanostructures was significantly improved, showing approximately 228.6 and 2.58 times higher than that of g-C3N4 nanostructures and ZnIn2S4 nanostructures, respectively. This enhancement in photocatalytic performance is attributed to the effective utilization of visible light and the efficient separation of photogenerated electron-hole pairs facilitated by the heterojunction structures. Moreover, the reusability test validated the outstanding performance of g-C3N4@ZnIn2S4 heterostructures, as they maintained high photocatalytic hydrogen production even after undergoing eight cycles without any noticeable decrease in efficiency. This study offers a promising strategy for designing and synthesizing an environmentally friendly g-C3N4@ZnIn2S4 heterojunction with potential applications in photocatalytic hydrogen evolution.