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

Abstract

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.