Easily recoverable Cd _x Zn_1−x S-Gel photocatalyst with a tunable band structure for efficient and stable H₂ production mediated by visible light

A photocatalyst consisting of a cellulose hydrogel loaded with Cd _x Zn_1−x S (Cd _x Zn_1−x S-Gel) was prepared, and its photocatalytic water splitting activity was studied. At room temperature, the Cd _x Zn_1−x S particles with an average size of about 3 nm were loaded in carboxymethyl cellulose hydrogel by an in situ chemical reaction. This synthesis method was simple and repeatable. Diffuse reflectance UV–vis results showed that it is possible to adjust the optical properties of the synthesized photocatalysts by adjusting their composition. Under visible light irradiation, the hydrogen production rate of the photocatalysts was greatly improved. In the absence of a co-catalyst, Cd_0.2Zn_0.8S-Gel obtained the highest hydrogen production rate of 1762.5 μmol g⁻¹ h⁻¹, which is almost 104 times of that of the pure CdS. Moreover, after four hydrogen production cycles, the hydrogen production rate did not decrease significantly, showing excellent stability. It is noteworthy that the Cd _x Zn_1−x S-Gel can easily be removed from the aqueous solution after hydrogen production. This is a new approach for manufacturing easy recoverable visible-light-driven photocatalysts, which is vital for hydrogen production through a “green” process.