Hollow and mesoporous ZnTe microspheres: synthesis and visible-light photocatalytic reduction of carbon dioxide into methane

Abstract

Hollow and mesoporous microstructures have been found to be an attractive class of materials due to their superior physical properties and potential applications. In the present work, a hydrothermal method has been used to synthesize hollow and mesoporous ZnTe hierarchical microspheres. The as-synthesized microspheres are characterized by a variety of techniques, including X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. Nitrogen adsorption–desorption measurements and the curve of relative pore size distribution via Brunauer–Emmett–Teller analysis confirm the existence of mesopores in the obtained nanomaterials. Different reaction parameters such as NaOH concentration, reaction temperature and time, and concentration of the tellurium precursor have been studied and the detailed growth mechanism has been proposed. These hollow and mesoporous microspheres are also used for the photoreduction of carbon dioxide into methane under visible-light illumination (λ ≥ 420 nm) with a solar energy conversion efficiency of 0.072%.