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 CO2 in form of valuable fuels. Recently, we set up an innovative concept of photoreactor to be applied to CO2 photoreduction, enabling operation up to 20 bar. This allows to improve CO2 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 TiO2 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. CH4 + H2, 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.