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

A series of ZnIn2S4 floriated microspheres consisting of flakes were synthesized by a facile template-free hydrothermal method. The obtained ZnIn2S4 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 ZnIn2S4 microspheres were investigated. The photocatalytic activities for hydrogen production of the as-prepared samples were evaluated under visible-light (lambda >= 420 nm) irradiation. It was found that the 1.0 wt % Pt-loaded ZnIn2S4 prepared hydrothermally at 160 degrees C with pH = 1.00 showed a higher and steady photoactivity for H-2 evolution from aqueous solutions containing sacrificial reagents SO32- and S2- 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.