Self-assembled three-dimensional flowerlike Mn0.8Cd0.2S microspheres as efficient visible-light-driven photocatalysts for H2 evolution and CO2 reduction

In this work, we demonstrated the polyvinylpyrrolidone-assisted solvothermal synthesis of three-dimensional (3D) flowerlike Mn0.8Cd0.2S microspheres assembled from nanosheets. The as-synthesized products were characterized by using various methods including powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microcopy/selected area electron diffraction, elemental mapping, X-ray photoelectron spectroscopy, inductively-coupled plasma emission spectroscopy, N2 adsorption–desorption, UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and photoelectrochemical experiments. The possible formation mechanism of the unique structures was discussed. The resultant 3D flowerlike Mn0.8Cd0.2S architectures exhibit better photocatalytic activities for H2 evolution and CO2 reduction under visible light irradiation than the Mn0.8Cd0.2S nanoparticles. A hydrogen evolution rate of 3560.3 μmol g−1 h−1 and a CH3OH production rate of 10.7 μmol g−1 h−1 are achieved on the flowerlike Mn0.8Cd0.2S microspheres. Several possible reasons for the enhanced photocatalytic activity of the Mn0.8Cd0.2S hierarchical microspheres have been taken into consideration. In addition, the Mn0.8Cd0.2S microspheres are stable during the reaction and can be used repeatedly.