Enhancing the photocatalytic reduction of CO2 with undoped and Cu-doped TiO2 nanofibers synthesized in supercritical medium

The photocatalytic reduction of CO2 with water vapour using titania nanofibers (TNFs) synthesized in supercritical medium has been assessed. TNFs have been produced from titanium isopropoxide (TTIP) precursor at different pressures (200-240 bar) and temperatures (40-80 degrees C). Synthesized materials were later characterized by scanning and transmission electron microscopy, BET surface area analysis, X-ray diffraction, and UV-vis diffuse reflectance spectroscopy. Better defined morphologies were obtained at the highest pressure and temperatures tested, so the catalyst synthesized at 240 bar and 60 degrees C was doped with copper (0.4-2 wt. %) in order to study the influence of metal doping on CO2 reduction. All undoped and Cu-doped TNFs have been found to exhibit higher CO2 reduction rates than commercial catalyst (P-25) and other TNF-based catalysts produced with traditional methods, although methane and CO remain the only two reaction products. Moreover, it has been found that copper doping improves CO2 conversion in comparison with the equivalent undoped catalyst.