Charge carrier trapping, recombination and transfer during TiO2 photocatalysis: An overview
Graphical abstract
Section snippets
Basic principles of semiconductor photocatalysis
According to literature surveys by Serpone et al. [1,2], the term photocatalysis firstly appeared in 1910 in a textbook of photochemistry. In 1911 a study about Prussian blue bleaching over illuminated ZnO particles was reported. Research in semiconductor photocatalysis grew in 1960–1970s and has surged since late 1980s. Up to now semiconductor photocatalysis has been developed as a versatile technology applicable in environmental remediation and solar energy conversion [[3], [4], [5], [6], [7]
Characterization techniques
Exploring the charge carrier kinetics is essential for understanding the photocatalytic mechanism occurring at semiconductor surface. Herein two key characterization techniques, namely, time-resolved spectroscopy and electron paramagnetic resonance (EPR) spectroscopy, are briefly introduced. The former technique is applied to monitor the charge carrier dynamics, while the latter is useful to identify the paramagnetic species formed upon reaction of the charge carriers.
Charge carrier trapping
The photogenerated charge carriers can be trapped in either in bulk or on the surface. In generally, surface trapping at either the subsurface or the surface region is preferred in semiconductor nanoparticles [70]. The temporal species including trapped holes, trapped electrons, and free electrons are the main states for charge carriers during the trapping stage. By using TAS in a wide wavelength range from 400 to 2500 nm, Yoshihara et al. [77] found that trapped holes and electrons are
Interfacial charge carrier transfer dynamics
After charge carrier separation the valence band holes and conduction band electrons can initialize the redox reactions. Photocatalytic reaction is a typical surface reaction. Adsorption-kinetic models, and, specifically, the Langmuir-Hinshelwood (L-H) model, are commonly applied to describe photocatalytic mineralization reactions [112]. Accordingly, it can be deduced that the photocatalytic reaction generally behaves as a pseudo-first-order reaction in kinetics, and its efficiency relies on a
Summary and perspective
We have overviewed recent progress in dynamics of interfacial electron transfer in photocatalysis with the assistants of various analytic techniques. Charge carrier generation, trapping, recombination, and interfacial transfer have been briefly described to illustrate how interfacial electron transfer perspectives can provide unique insights into the field of photocatalysis and motivate more knowledge sharing in research to cover major aspects of photocatalysis from fundamentals to
Acknowledgements
This work is supported by the National Nature Science Foundation of China (No. 51772094), Fundamental Research Funds for the Central Universities (No. JB2016ZZD04) and Beijing Natural Science Foundation (No. 2172052)
References (151)
- et al.
TiO2 photocatalysis and related surface phenomena
Surf. Sci. Rep.
(2008) - et al.
Titanium dioxide photocatalysis
J Photochem. Photobiol. C: Photochem. Rev.
(2000) Photocatalytic water treatment: solar energy applications
Sol. Energy
(2004)- et al.
Hydrous TiO2 spheres: An excellent platform for the rational design of mesoporous anatase spheres for photoelectrochemical applications
Catal. Today
(2014) - et al.
Anatase and rutile in Evonik Aeroxide P25: Heterojunctioned or individual nanoparticles?
Catal. Today
(2018) - et al.
TiO2(B) a new form of titanium dioxide and the potassium octatitanate K2Ti8O17
Mat. Res. Bull.
(1980) - et al.
Kinetics and mechanisms of charge transfer processes in photocatalytic systems: a review
J Photochem. Photobiol. C: Photochem. Rev.
(2012) - et al.
The role of electron transfer in photocatalysis: Fact and fictions
Appl. Catal. B
(2012) - et al.
Kinetics of the photocatalytic water-splitting reaction on TiO2 and Pt/TiO2 studied by time-resolved infrared absorption spectroscopy
J. Mol. Catal. A Chem.
(2003) Representative examples of infrared spectroscopy uses in semiconductor photocatalysis
Catal. Today
(2014)
Transient absorption spectra of nanocrystalline TiO2 films at high excitation density
Chem. Phys. Lett.
The use of diffuse reflectance laser flash photolysis to study primary photoprocesses in anisotropic media
Tetrahedron
Transient photoconductivity measurements of ultrasonic spray pyrolyzed tungsten oxide thin films
Mater. Res. Bull.
Probing paramagnetic species in titania-based heterogeneous photocatalysis by electron spin resonance (ESR) spectroscopy—A mini review
Chem. Eng. J.
In situ EPR studies of electron trapping in a nanocrystalline rutile
J. Photochem. Photobiol. A
EPR studies of electron and hole trapping in titania photocatalysts
Catal. Today
Photoluminescence and photoactivity of titania particles prepared by the sol–gel technique: effect of calcination temperature
J. Photochem. Photobiol. A
Morphology-sensitive trapping states of photogenerated charge carriers on SrTiO3 particles studied by time-resolved visible to mid-IR absorption spectroscopy: The effects of molten salt flux treatments
J. Photochem. Photobiol. A
Synthesis of photocatalytic TiO2 nanoparticles: optimization of the preparation conditions
J. Photochem. Photobiol. A
On the genesis of heterogeneous photocatalysis: a brief historical perspective in the period 1910 to the mid-1980s
Photochem. Photobiol. Sci.
A historical introduction to photocatalysis
Light-induced redox reactions in nanocrystalline systems
Chem. Rev.
Photocatalysis on TiO2 surfaces: Principles, mechanisms, and selected results
Chem. Rev.
Understanding TiO2 photocatalysis: Mechanisms and materials
Chem. Rev.
Photoelectrocatalytic materials for environmental applications
J. Mater. Chem.
Porous photocatalysts for advanced water purifications
J. Mater. Chem.
Solution-phase synthesis of titanium dioxide nanoparticles and nanocrystals
Chem. Rev.
Recent progress in the synthesis of spherical titania nanostructures and their applications
Adv. Funct. Mater.
Hollow micro-/nanostructures: synthesis and applications
Adv. Mater.
Titanium dioxide crystals with tailored facets
Chem. Rev.
Recent advances in micro-/nano-structured hollow spheres for energy applications: From simple to complex systems
Energy Environ. Sci.
Hierarchical TiO2 microspheres: synthesis, structural control and their applications in dye-sensitized solar cells
RSC Adv.
Comparison of dye-sensitized rutile- and anatase-based TiO2 solar cells
J. Phys. Chem. B
Band alignment of rutile and anatase TiO2
Nat. Mater.
Titanium dioxide nanomaterials: synthesis, properties, modifications, and applications
Chem. Rev.
Understanding polymorphic phase transformation behavior during growth of nanocrystalline aggregates
J. Phys. Chem. B
Tailored titanium dioxide nanomaterials: Anatase nanoparticles and brookite nanorods as highly active photocatalysts
Chem. Mater.
Brookite: Nothing new under the sun?
Catalysts
Influence of brookite impurities on the raman spectrum of TiO2 anatase nanocrystals
J. Phys. Chem. C
Trapping-induced enhancement of photocatalytic activity on brookite TiO2 powders: Comparison with anatase and rutile TiO2 powders
ACS Catal.
Enhanced photocatalytic hydrogen production with synergistic two-phase anatase/brookite TiO2 nanostructures
J. Phys. Chem. C
Photocatalytic CO2 reduction with H2O on TiO2 nanocrystals: Comparison of anatase, rutile, and brookite polymorphs and exploration of surface chemistry
ACS Catal.
Hierarchical tubular structures constructed from ultrathin TiO2(B) nanosheets for highly reversible lithium storage
Energy Environ. Sci.
From titanates to TiO2 nanostructures: Controllable synthesis, growth mechanism, and applications
Sci. China Chem.
Di(cyclooctatetraene)titanium and tri(cyclooctatetraene)dititanium
Angew. Chem. Int. Ed.
Mesoporous TiO2-B microspheres with superior rate performance for lithium ion batteries
Adv. Mater.
Nanosheet-constructed porous TiO2-B for advanced lithium ion batteries
Adv. Mater.
Environmental applications of semiconductor photocatalysis
Chem. Rev.
Reactivity of trapped and accumulated electrons in titanium dioxide photocatalysis
Catalysts
In situ mechanistic investigation at the liquid/solid interface by attenuated total reflectance FTIR: ethanol photo-oxidation over pristine and platinized TiO2 (P25)
ACS Catal.
Cited by (379)
Flower-like superstructure of boron carbon nitride nanosheets with adjustable band gaps for photocatalytic hydrogen peroxide production
2024, Journal of Materials Science and TechnologySynthesis of isotype heterojunction by series calcination of multicomponent for high efficiency photocatalytic reduction of uranium
2024, Journal of Solid State ChemistryPhotocatalytically active Ag-doped TiO<inf>2</inf> coatings developed by plasma electrolytic oxidation in the presence of colloidal Ag nanoparticles
2024, Journal of Physics and Chemistry of SolidsS-scheme homojunction and activate site engineering over TiO<inf>2</inf> for highly efficient photocatalytic nitrogen fixation
2024, Chemical Engineering Journal
- 1
These authors have equal contribution to this work.