First-principles prediction of new photocatalyst materials with visible-light absorption and improved charge separation: surface modification of rutile TiO₂ with nanoclusters of MgO and Ga₂O₃.
Titanium dioxide is an important and widely studied photocatalytic material, but to achieve photocatalytic activity under visible-light absorption, it needs to have a narrower band gap and reduced charge carrier recombination. First-principles simulations are presented in this paper to show that heterostructures of rutil TiO₂ modified with nanoclusters of MgO and Ga₂O₃ will be new photocatalytically active materials in the UV (MgO-TiO₂) and visible (Ga₂O₃-TiO₂) regions of the solar spectrum. In particular, our investigations of a model of the excited state of the heterostructures demonstrate that upon light excitation electrons and holes can be separated onto the TiO₂ surface and the metal oxide nanocluster, which will reduce charge recombination and improve photocatalytic activity. For MgO-modified TiO₂, no significant band gap change is predicted, but for Ga₂O₃-modified TiO₂ we predict a band gap change of up to 0.6 eV, which is sufficient to induce visible light absorption. Comparisons with unmodified TiO₂ and other TiO₂-based photocatalyst structures are presented.
Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland. michael.nolan@tyndall.ie
Michael
M
Nolan
D000042:Absorption; D002384:Catalysis; D003198:Computer Simulation; D005708:Gallium / Q000737:chemistry*; D008027:Light; D008277:Magnesium Oxide / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008956:Models, Chemical; D010316:Particle Size; D012031:Refractometry; D012542:Scattering, Radiation; D055672:Static Electricity; D014025:Titanium / Q000737:chemistry*
C009495:titanium dioxide; D008277:Magnesium Oxide; C038863:gallium oxide; D005708:Gallium; D014025:Titanium