Significantly boosted photocatalytic hydrogen evolution by Pd–TiO ₂ /ZnIn ₂ S ₄ nanowires heterojunction under simulated sunlight

In this work, Pd-TiO₂/ZnIn₂S₄nanowires (Pd-Ti-Nws/ZIS) heterostructures catalysts were prepared and applied to photocatalytic hydrogen evolution under simulated sunlight. The results revealed that the hydrogen production rate of Pd-Ti-Nws-40/ZIS was as high as 66.7 mmol·g^-1·h^-1, which was 20.5 and 418 times as much as that of pure ZIS and Pd-Ti-Nws, respectively. After 5 cycles, the hydrogen production of the photocatalyst can still reach about 60 mmol within 120 min. According to the results of photochemistry and x-ray photoelectron spectroscopy, Pd-Ti-Nws/ZIS meets the S-scheme heterojunction system, which is beneficial to inhibit the recombination of photogenerated holes and electrons and increase carrier transport rate through the S-scheme heterojunction. Under light radiation, Pd-Ti-Nws is positively charged due to the accumulation of holes, and ZIS is negatively charged due to the accumulation of electrons with higher reducing power. Moreover, Pd nanoparticles obviously improve the response range and intensity of the catalyst to sunlight. Therefore, the photocatalytic hydrogen production rate obviously increased. This work provides a reasonable method for designing efficient catalysts for photocatalytic hydrogen production.