Recent Advances in Ternary Metal Oxides Modified by N Atom for Photocatalysis

Abstract

Ternary metal oxides (TMOs) with flexible band structures are of significant potential in the field of photocatalysis. The efficient utilization of renewable and green solar energy is of great importance to developing photocatalysts. To date, a wide range of TMOs systems has been developed as photocatalysts for water and air purification, but their practical applications in visible light-assisted chemical reactions are hindered mainly by its poor visible light absorption capacity. Introduction of N atoms into TMOs can narrow the band-gap energy to a lower value, enhance the absorption of visible light and suppress the recombination rate of photogenerated electrons and holes, thus improving the photocatalytic performance. This review summarizes the recent research on N-modified TMOs, including the influence of N doping amounts, N doping sites, and N-induced phase transformation. The introduced N greatly tuned the optical properties, electronic structure, and photocatalytic activity of the TMOs. The optimal N concentration and the influence of N doping sites are investigated. The substitutional N and interstitial N contributed differently to the band gap and electron transport. The introduced N can tune the vacancies in TMOs due to the charge compensation, which is vital for inducing different activity and selectivity. The topochemical ammonolysis process can convert TMOs to oxynitride with visible light absorption. By altering the band structures, these oxynitride materials showed enhanced photocatalytic activity. This review provides an overview of recent advances in N-doped TMOs and oxynitrides derived from TMOs as photocatalysts for environmental applications, as well as some relevant pointers for future burgeoning research development.

Perspectives for Photocatalytic Decomposition of Environmental Pollutants and Pathogens on Photoactive Particles of Soil Minerals

“…Another popular and quite effective way to 'tune' EBG, Fermi-level (i.e. reduction-potentials of CB e  and VB h  ), the molar absorption coefficient (), and other characteristics of the material, is by the engineering that introduces dopants and other defects into the structure of the semiconductor [47][48][49][50][51][52][53][54][55][56]. Thus, under certain conditions, even high dielectric constant oxides like ZrO2 can be utilized to build binary oxide photocatalysts [57][58][59][60][61].…”

Enhanced visible-light photocatalytic activity of N-doped C/Na2Ti6O13/TiO2 hollow spheres for efficient dye degradation

“…Asahi et al extensively studied N-doping to improve the photo-efficiency of TiO 2 by annealing it in N 2 gas, resulting in visible light-responsive photocatalytic activity and improved charge carrier separation [ 27 ]. Additionally, N-doping in ternary metal oxides (TMOs) narrows the bandgap, facilitates electron capture by forming vacancies, reduces the recombination velocity of photoinduced carriers, and enhances photocatalytic degradation [ 28 ]. However, compared to the extensive research on N-doping in binary metal oxides, such as TiO 2 , the exploration of N-doping in TMOs has received relatively less attention.…”

Mechanistic Insights into the Phase Formation of an Atypical Iron Oxynitride (FexOyNz) System and Its Multifunctional Photocatalytic Applications

“…In this direction, tantalum oxynitride (TaON) is often used to demonstrate how an “oxynitride” phase influences the band structure of a system compared to its oxide (Ta 2 O 5 ) and nitride (Ta 3 N 5 ) phases . Importantly, it is reported that the band gap energy of Ta 2 O 5 is decreased from ∼3.9 to ∼2.4 eV in the case of TaON. , Similarly, many oxynitride systems have also been substantially demonstrated to have a decreased band gap energy compared to their oxide phases, along with offering improved overall photocatalytic efficiencies. − However, many conventional oxide-based photocatalysts (such as TiO 2 , ZnO, Fe 2 O 3 , etc.) have been hardly developed in their oxynitride form toward their photocatalytic applications …”

“…11 Importantly, it is reported that the band gap energy of Ta 2 O 5 is decreased from ∼3.9 to ∼2.4 eV in the case of TaON. 12, 13 Similarly, many oxynitride systems have also been substantially demonstrated to have a decreased band gap energy compared to their oxide phases, along with offering improved overall photocatalytic efficiencies. 14−16 However, many conventional oxide-based photocatalysts (such as TiO 2 , ZnO, Fe 2 O 3 , etc.)…”