Solar hydrogen generation from ambient humidity using functionalized porous photoanodes

Solar hydrogen is a promising sustainable energy vector and steady progress has been made in the development of photoelectrochemical cells. Most research in this field has focused on using acidic or alkaline liquid electrolytes for ionic transfer. However, the performance is limited by (i) scattering of light and blocking of catalytic sites by gas bubbles and (ii) mass transport limitations. An attractive alternative to a liquid water feedstock is to use the water vapor present as humidity in ambient air, which has been demonstrated to mitigate the above problems and can expand the geographical range where these devices can be utilized. We show here how the functionalization of porous TiO2 and WO3 photoanodes with solid electrolytes - proton conducting Aquivion® and Nafion® ionomers, enables the capture of water from ambient air and allows subsequent photoelectrochemical hydrogen production. The optimization strategy of the photoanode functionalization was examined through testing the effect of ionomer lo...