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

Abstract

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 CO<inf>2</inf> and water vapor to CH<inf>4</inf>. The C,N-TNT sample with an intermediate doping concentration yields the maximum methane yield of 9.75 μmol/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 CO<inf>2</inf> 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. © 2015 Elsevier B.V. All rights reserved.