Highly efficient Zn1−xCdxS catalysts with sphalerite structures synthesized via a novel green method for hydrogen production by water splitting

Abstract

The present study focuses on the development of a photochemical reactor coupled with a mass spectrometer for the in situ detection of the H₂ generation rate of the photochemical water splitting process. To do so, sphalerite-type Zn_1−xCd_xS catalysts were synthesized, characterized, and tested as a proof-of-concept for the development of the equipment with applied materials. The sulphides were obtained by means of a green synthetic method, which avoids the use of toxic non-aqueous solvents and the application of high temperatures. The prepared Zn/Cd sulphide catalysts were physicochemically characterized by XRD, TEM, diffuse reflectance spectroscopy and electrochemical impedance spectroscopy. Afterwards, the catalytic performance of the materials towards hydrogen (photo)production was studied by means of the photoreactor coupled with the mass spectrometer. On the one hand, the results show the suitability of the photoreactor designed to measure the reaction rate under in situ conditions, exhibiting clear changes in the scan rate upon increasing the light energy (from visible to UV light). On the other hand, a high hydrogen production was achieved for Zn_0.7Cd_0.3S with a maximum value of 29.5 mmol g_cat⁻¹ after 100 minutes under visible light. This production is significantly higher than those previously reported in the literature for other standard materials, indicating the high potential of our materials for green hydrogen production.