CO2 photoconversion to fuels under high pressure: effect of TiO2 phase and of unconventional reaction conditions

Artificial photosynthesis is an up to date topic for the fixation of CO 2 in form of valuable fuels. Recently, we set up an innovative concept of photoreactor to be applied to CO 2 photoreduction, enabling operation up to 20 bar. This allows to improve CO 2 solubility and to explore unconventional operating conditions for this very challenging reaction. Following a preliminary communication, to demonstrate the validity of the approach systematic testing has been here carried out on different TiO 2 photocatalysts (anatase, rutile and anatase + rutile) doped with 0.1 wt% Au, by tuning pressure, temperature and pH. The operating conditions have been selected to maximise the production of gas phase products, i.e. CH 4 + H 2 , with respect to liquid phase organic compounds. The present results overperform many of the recent achievements reported in the literature and throw the basis for a further optimisation of the photocatalytic material and of the photoreactor. Effect of CO 2 saturation and reactor pressure on H 2 (full triangles) and CH 4 (circles) productivity at pH = 11.4, T = 65 °C. H 2 productivity (empty triangles) at pH 5.5, T = 65 °C. Sample 0.1 wt% Au/P25.