Photocatalytic Reduction of Carbon dioxide to Renewable Methane using Titanium dioxide modified with Bismuth and Copper

Research Subject: 

The conversion of anthropogenous CO2 gas into value-add chemicals known as solar fuel technology attracted much consideration from the beginning of the 21st century owing to the potential of this technology in solving the climate change and energy shortage issues.

Research Approach:

 In the current study, Bismuth and copper modified TiO2 were prepared using sol-gel and wet impregnation method in order to investigate as a catalyst for photocatalytic conversion of carbon dioxide into renewable methane.  

The results of X-ray diffraction analysis, Field emission scanning microscope images and Transmission electron microscope images demonstrated that titanium dioxide nanoparticles with 20 nm in size were synthesized that after the addition of bismuth, the size of particles became smaller. Also, using energy dispersive x-ray analysis and elemental mapping technique, it was determined that the bismuth and copper were uniformly inserted in the prepared nanoparticles. Diffuse reflectance spectroscopy showed that the bandgap became smaller in bismuth and copper-containing samples, which resulted in visible light absorption. In addition, photoluminescence spectroscopy showed an impressive decrease in the rate of electron-hole separation in the prepared nanocomposite. The result of CO2 photoreduction experiments revealed that the incorporation of 3 wt% Bismuth and 1.5 wt% copper into the structure of TiO2 would increase the amount of methane production to 7.6 times greater than bare TiO2. This superior activity for methane generation could be related to the ability of bismuth compounds in adsorption and activation of carbon dioxide molecules and also the efficient separation of charge carriers given by copper. Additionally, the smaller particle size and increase in the surface area had also a positive effect on the CO2 reduction enhancement.