Nonmetal Surface Doping and Carrier Transportation in Black Tio2 And Its Application in Photoelectrochemical Water Splitting, A Computational Study
DescriptionBlack TiO2 is a promising photocatalyst that can be used in photoelectrochemcial (PEC) applications such as H2 and O2 production (ideal carriers of clean chemical energy) by water splitting. In our recent work, we have successfully obtained a surface nitrogendoped rutile TiO2 with good photo-induced charge separation performance. It is realized that certain doping could not only improve the conductivity of charge carriers but also significantly improve the optical absorption properties. Although doping can directly enhance the conductivity, there is still much room for improvement. Complicated experimental results are by far so poorly understood that convincing doping mechanisms are urgently demanded. Systematic theoretical calculations would be beneficial for understanding the intrinsic mechanism so as to guide the doping strategy and optimize PEC conditions in green energy applications.We believe that the surface passivation mechanism accompanied by charge transfer plays an important role in the surface doping of black TiO2. Therefore, we propose in this project to conduct computational research in accordance with such a mechanism to find optimal doping design and to complement previous explorations based on substitutional and interstitial doping mechanisms. We will model the doping systems by placing nonmetal dopants such as H, B, C, N, S and P atoms into the surface nanostructures of black TiO2. We will simulate the gradient doping of these atoms in the surface regions as well as the adsorption and desorption of water molecules and other possible species such as H+/OH- and O2/H2O involved in PEC. The calculation will include geometry optimizations and molecular dynamics simulations at ground states and/or excited states, transition state searches of possible chemical reactions involved, and charge populations as well as band structures and density of states, at the level of accurate density functional theory (DFT) and time-dependent DFT functionals. We expect that our work would deliver useful information about doping types and configurations as determined by charge transfers, which provide the carriers for the conduction due to the dopant accumulation at interface and surface of the black TiO2 as well as the adsorptions and desorptions of species from the electrolyte. We will also reveal the interfacial chemical reactions involving dopants in PEC applications and identify the reactions with products on stable surfaces from photoinduced reconstruction of the black TiO2 material.
|Effective start/end date||1/01/20 → …|