Growth of tunable Au-BaO@TiO2/CdS heterostructures: Acceleration of hydrogen evolution from water splitting

Abstract

The need for efficient and sustainable catalysts to generate clean energy through water splitting is a requirement of the current era. In this study, TiO2/CdS heterostructures were synthesized using hydrothermal reaction. To enhance the photocatalytic performances of TiO2/CdS, BaO and Au were in-situ deposited via chemical reduction and hydrothermal treatment at 165 °C for 6 h. Finally Au-BaO@TiO2/CdS catalysts were synthesized for photocatalytic hydrogen generation from water splitting. The optical and structural properties of catalysts were examined with FT-IR, XRD, Raman and UV–Vis-DRS techniques. The morphology and chemical properties of catalysts were obtained using EDX, AFM, XPS and SEM techniques. Photoreaction and H2 production activities were monitored at Pyrex reactor (150 mL) and GC-TCD (Shimadzu-2014). The tunable fabrication approach provides a novel strategy for tailoring the properties of TiO2/CdS heterostructures, allowing for optimization of their photocatalytic performance. The enhanced surface plasmon impact achieved through Au-NPs incorporation opens up new possibilities for improving the efficiency. The results demonstrate that Au-BaO@TiO2/CdS catalysts exhibit significantly higher H2 generation activity (13.54 mmol g−1h−1). This H2 evolution activity was found higher than other catalysts i.e. TiO2/CdS, BaO@TiO2/CdS and Au@TiO2/CdS. Higher catalytic activity in case of Au-BaO@TiO2/CdS was attributed to the co-existence of BaO and Au-NPs. The Au-NPs provide hot electrons (via SPR effect) that increase the electron pool over the surfaces of TiO2/CdS heterostructures. During photoreaction, BaO assists the transfer of photoexcited electrons from TiO2/CdS system to the active centers (i.e. Au cocatalysts). In addition, various factors that affect the H2 production rates (i.e. pH, temperature, catalyst dose and effect of light intensity) were evaluated and discussed.