Synthesis of a Bi2S3/CeO2 nanocatalyst and its visible light-driven conversion of CO2 into CH3OH and CH4

Due to shortage of fossil fuels and rapid growth of energy demand, exploration of new energy resources becomes essential. Moreover, the CO2 level is increasing day by day, which has caused global warming as well as environmental pollution. Designing a suitable photocatalyst that can solve both issues always remains a challenge. In this work, we have designed such a nanocatalyst that may be helpful in solving these issues. A hydrothermal method has been used for the synthesis of Bi2S3 and CeO2, and their nanocomposite (Bi2S3/CeO2) has been prepared by a two-step method. X-ray diffraction results confirm the formation of the target materials. High resolution transmission electron microscopy and scanning electron microscopy show that Bi2S3 is rod-shaped and CeO2 is in the form of spherical particles. Both Bi2S3 and CeO2 are well distributed in the nanocomposite. The optical properties of the obtained nano-catalysts are analyzed by UV/visible absorption spectroscopy and photoluminescence spectroscopy. X-ray photoelectron spectra are used to determine the position of the valence band. All the synthesized materials are applied to the photoreduction of CO2 with water under visible-light irradiation (lambda >= 420 nm). The Bi2S3/CeO2 nanocomposite exhibits higher yields of methane and methanol than the individual semiconductors. Moreover, the nanocomposite shows improved stability compared to the individual catalysts.