Photocatalytic conversion of CO2 to hydrocarbon fuel using carbon and nitrogen co-doped sodium titanate nanotubes

Carbon and nitrogen co-doped sodium titanate nanotubes (C,N-TNT) active under simulated solar light are synthesized by a simple two-step process comprising an alkaline hydrothermal technique followed by calcination. Different samples of C,N-TNT with varied dopant concentrations are achieved by changing the amount of urea as a nitrogen and carbon dopants. The photocatalysts are characterized using numerous experimental techniques, and under simulated solar light investigated for the photocatalytic conversion of CO2 and water vapor to CH4. The C,N-TNT sample with an intermediate doping concentration yields the maximum methane yield of 9.75 mu mol/g h. The key factors contributing in the improvement of photocatalyst performance includes light absorption, surface area and Na+ ions concentration in TNT acting as CO2 adsorption site and photogenerated electrons recombination centers. The higher doping levels results in lower specific surface areas leading to decrease in photocatalyst performance. Our results suggest co-doping of nanostructured photocatalysts is an excellent pathway for improving textural and photocatalytic properties for the respective application domain. (C) 2015 Elsevier B.V. All rights reserved.