Enhanced photocatalytic hydrogen production of CdS embedded in cationic hydrogel

In this study, we describe the successful fabrication of CdS in ionic hydrogels by an in situ growth method and demonstrate that the as-prepared CdS in hydrogels (CdS/HGel) can be used as cost-effective and recyclable catalysts for photocatalytic hydrogen generation. The structure and morphology of CdS/HGels were characterized by various techniques including X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. The resultant CdS in cationic hydrogel (CdS/HGelPDAM2) showed the best performance of photocatalytic hydrogen production and the hydrogen production rate was up to 10.35 or 7.70 mmol h−1 g−1 when triethanolamine or Na2S–Na2SO3 was used as sacrificial agent. However, CdS in anionic hydrogel (CdS/HGelPAAM) showed poor photocatalytic hydrogen production performance under the same conditions. The solution pH and sacrificial agent type are also indispensable factors that affect the photocatalytic hydrogen production. The enhancement of hydrogen production comes from interaction between polymer chains and Cd2+, high dispersibility of CaS nanoparticles in hydrogels, high hydrophilic and swelling ability of hydrogel, high diffusion rate of reactant in hydrogel, and inhibited binding possibility of photogenerated electron-hole pairs. Since CdS/HGelPDAM has excellent hydrogen production efficiency and ease recovery property, it will be a potential photocatalyst for photocatalytic reactions.