Template-Free Hydrothermal Synthesis of ZnIn₂S₄ Floriated Microsphere as an Efficient Photocatalyst for H₂ Production under Visible-Light Irradiation

Abstract

A series of ZnIn 2 S 4 floriated microspheres consisting of flakes were synthesized by a facile template-free hydrothermal method. The obtained ZnIn 2 S 4 products were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV−vis diffuse reflectance absorption spectroscopy, and nitrogen adsorption measurement. The effects of hydrothermal temperature and pH value on the crystal structures, morphologies, and optical properties of ZnIn 2 S 4 microspheres were investigated. The photocatalytic activities for hydrogen production of the as-prepared samples were evaluated under visible-light (λ ≥ 420 nm) irradiation. It was found that the 1.0 wt % Pt-loaded ZnIn 2 S 4 prepared hydrothermally at 160 °C with pH = 1.00 showed a higher and steady photoactivity for H 2 evolution from aqueous solutions containing sacrificial reagents SO 3 2− and S 2− than the products prepared at other hydrothermal temperatures. Moreover, an apparent quantum efficiency of up to 34.3% was achieved under incident monochromatic light of 420 nm, significantly higher than previously reported values.