Fe₁/TiO₂ Hollow Microspheres: Fe and Ti Dual Active Sites Boosting the Photocatalytic Oxidation of NO

Abstract

Recently, single‐atom catalysts have aroused extensive attention in fields of clean energy and environmental protection due to their unique activity and efficient utilization of the active atoms. It is of great importance but still remains a great challenge to unveil the effect of single atoms on precise catalysis. Herein, it is reported that doping TiO2 hollow microspheres (TiO2‐HMSs) with single atomic Fe can boost the photoreactivity of TiO2‐HMSs towards NO oxidation due to the synergistic effects of atomically dispersed Fe and bonded Ti atom which act as dual active sites. The atomically dispersed Fe atoms occupy the subsurface Ti vacancies, and the interaction between Ti 3d and Fe 3d orbitals result in the formation of FeTi bond. Single atomic Fe modulates the electronic structure of the bonded Ti atoms by electron transfer, which facilitates the adsorption and activation of NO and O2 at Fe and bonded Ti sites, respectively. In addition, the introduction of single atomic Fe sharply suppresses the production of toxic NO2 byproduct. The synergistic effects of the dual active sites then cause a drastic promotion in photocatalytic oxidation of NO.

Research Progress and Application of Single-Atom Catalysts: A Review

“…Through first-principles calculations, Li et al [78] found that the Cr single-atom catalyst supported on graphene is the most promising single-atom catalyst for NO oxidation. Compared with precious metals, the 3D orbitals of transition metals Fe and Co do not form paired electrons, so they have unique activities [79]. In addition, the synergy between the double active sites of metal atoms can also be used to catalyze the oxidation of NO, so that the adsorption of NO and O 2 on the active surface is enhanced, and at the same time, the occurrence of side reactions is inhibited.…”

In situ Irradiated XPS Investigation on S‐Scheme TiO2@ZnIn2S4 Photocatalyst for Efficient Photocatalytic CO2 Reduction

“…[15,17,19,37,38] Photocatalysts with hollow structures have attracted great attention owing to manifold advantages including larger specific surface area, abundant active sites, shortened diffusion distance as well as improved light reflection and scattering. [37,[39][40][41][42][43][44] Therefore, the design of hollow S-scheme heterojunction photocatalyst is of vital importance to enhance photocatalytic performance.ZnIn 2 S 4 , as a typical reduction photocatalyst, stands out for its layered structure, narrow bandgap, suitable redox potentials, and good chemical stability. And it has been used for various photocatalytic applications including hydrogen production, CO 2 reduction, and organic degradation.…”

“…[15,17,19,37,38] Photocatalysts with hollow structures have attracted great attention owing to manifold advantages including larger specific surface area, abundant active sites, shortened diffusion distance as well as improved light reflection and scattering. [37,[39][40][41][42][43][44] Therefore, the design of hollow S-scheme heterojunction photocatalyst is of vital importance to enhance photocatalytic performance.…”

Single atoms supported on metal oxides for energy catalysis

“…178,243 In addition to the CO 2 reduction reaction, photocatalysis based on SACs has also made some achievements in other reactions. 24,98,140,244 For example, Wang and co-workers designed a novel molten salt method (MSM) to prepare a TiO 2 -supported single Ni co catalyst for the hydrogen evolution reaction (HER). 24 In the MSM process, it is found that Ni atoms on TiO 2 are benecial to the formation of oxygen vacancies, which facilitate the transfer of charge and the reaction of hydrogen evolution.…”