Mechanistic insights into water adsorption and dissociation on amorphous TiO2-based catalysts

Despite having defects, amorphous titanium dioxide (aTiO(2)) have attracted significant scientific attention recently. Pristine, as well as various doped aTiO(2) catalysts, have been proposed as the potential photocatalysts for hydrogen production. Taking one step further, in this work, the author investigated the molecular and dissociative adsorption of water on the surfaces of pristine and Fe2+ doped aTiO(2) catalysts by using density functional theory with Hubbard energy correction (DFT+U). The adsorption energy calculations indicate that even though there is a relatively higher spatial distance between the adsorbed water molecule and the aTiO(2) surface, pristine aTiO(2) surface is capable of anchoring H2O molecule more strongly than the doped aTiO(2) as well as the rutile (1 1 0) surface. Further, it was found that unlike water dissociation on crystalline TiO2 surfaces, water on pristine aTiO(2) catalyst experience the dissociation barrier. However, this barrier reduces significantly when aTiO(2) is doped with Fe2+, providing an alternative route for the development of an inexpensive and more abundant catalyst for water splitting. [GRAPHICS] Graphical abstract showing the reduction in water splitting barrier due to doping in amorphous TiO2, bringing the catalytic acivity of amorphous TiO2 close to crystalline TiO2.