IMPACT OF CO-DOPING AND TRI-DOPING ON THE PHOTOCATALYSIS OF ANATASE TiO2

Abstract

TiO2 photocatalysis is widely employed in several applications and products in the environmental and energy areas, including self-cleaning surfaces, air and water purification, sterilization, hydrogen evolution, and photoelectrochemical conversion. Each one of these
applications is possible under ultraviolet (UV) light. Anatase TiO2 is the most commonly used catalyst due to its abundance and low cost. However, its high band gap reduces its efficiency. Experiments have used various metal and non-metal atoms to lower the anatase’s band gap and shift photocatalyst activity under visible regions. In this study, we attempted to employ a hybrid periodic Density Functional Theory. The DFT method is used to simulate the solid-state phase of an anatase photocatalyst and investigate how co-doping of (N, Cu), (N, Fe), and tri-doping of (N, Fe, Cu) can reduce the band gap. Co-doping with (Cu, N) lowers the band gap of pure anatase from 2.191 to 1.58 eV. It will produce a new energy level over the valence band and below the CB of TiO2 and hence reduce the band gap of TiO2. This will cause a p-type because the fermi level is shifted below the valence band. Similarly, co-doping with (Fe, N) lowers the band gap of pure anatase from 2.191 to 1.42 eV. Tri-doping reduces the band value by up to 1eV. The optical absorption coefficient results demonstrate that tri-doping (Cu, Fe, N) in anatase has higher optical absorption in the visible region when compared to the other two co-doped anatase titanium dioxide. The explanation for this is recombination and the oxidation-reduction process.