Solar fuel generation over nature-inspired recyclable TiO2/g-C3N4 S-scheme hierarchical thin-film photocatalyst

Wang, Libo; Fei, Xingang; Zhang, Liuyang; Yu, Jiaguo; Ma, Yuhua

doi:10.1016/j.jmst.2021.10.016

Cited by 131 publications

(21 citation statements)

References 53 publications

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“…For example, WO3 and BiVO4 have strong oxidative ability and weak reductive ability, which are mostly used to degrade organic pollutants 85 , sterilization 86 , and NO removal 87,88 . The electrons of CdS and g-C3N4 photocatalysts with strong reductive ability are mainly used for photocatalytic H2 production 89 and CO2 photoreduction 90 , while the holes with weak oxidative ability are quenched by adding sacrificial agents. These visible photocatalysts not only suffer the problem of weak oxidation or reduction ability at one end, due to the inability of charges to be utilized in time 91 .…”

Section: Basic Principles Of Photocatalysismentioning

confidence: 99%

“…Therefore, the applications of their complexes in different fields of photocatalysis have been extensively investigated. There are hundreds of research papers on g-C3N4/TiO2 composite photocatalysts in the past decade 90,[107][108][109][110][111][112][113][114][115] . However, unfortunately, the debate about whether the g-C3N4/TiO2 composite photocatalyst is Type-II or direct Zscheme continued until 2016, and the direct Z-scheme mechanism of the g-C3N4/TiO2 composite photocatalyst was confirmed by more researchers.…”

Section: Dft Calculation For Photocatalytic Overall Redox Reactionsmentioning

confidence: 99%

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Overall Utilization of Photoexcited Charges for Simultaneous Photocatalytic Redox Reactions

Wang¹,

Wang²,

Zhang³

et al. 2022

Acta Physico Chimica Sinica

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The photoconversion of CO2 to carbon-containing fuels, splitting water into H2, selective organic synthesis, reduction of N2 to NH3, and hazardous organic contaminant degradation represent feasible schemes for solving environmental and energy issues. In 1972, TiO2 was applied for decomposing water into H2 and O2 via photocatalysis. Owing to its the low visible-light utilization, fast charge recombination, and high energy barrier for water oxidation, overall photocatalytic water-splitting efficiency is extremely low. Because H2 is more economically valuable than O2, sacrificial agent-assisted photocatalytic H2 evolution has been extensively investigated. Because the sacrificial agent can quickly consume photoexcited holes and effectively reduce the water oxidation energy barrier, photocatalytic H2 evolution efficiency can be increased by 3-4 orders of magnitude compared to photocatalytic water splitting. However, the overuse of sacrificial agents contributes to wasted photoexcited holes and expensive processes, while presenting potential environmental issues. Recently, overall charge utilization and improved redox efficiency have been achieved by coupling photocatalytic reduction with oxidation reactions. Moreover, overall charge utilization can boost charge separation and increase photocatalyst durability. However, the photocatalytic mechanism of the overall redox reactions remains unclear, owing to the complex reaction processes and design difficulties. Herein, the basic principles of photocatalysis are discussed from the perspective of light harvesting, photoexcited charge separation, thermodynamics, and redox reaction kinetics. Photocatalytic redox reactions, including overall water photodecomposition, photocatalytic H2 evolution coupled with organic oxidation, photocatalytic CO2 reduction coupled with organic oxidation, photocatalytic H2O2 production coupled with organic oxidation, photocatalytic N2 reduction coupled with N2 oxidation, and photocatalytic organic reduction coupled with organic oxidation, can be systematically classified according to the coupling of photocatalytic oxidation reactions with photocatalytic reduction reactions. Subsequently, the design of photocatalytic redox reactions is considered in terms of the modulation of photocatalyst materials, reaction conditions, and diversity of reactants and products. In addition, the vital role of density functional theory (DFT) calculations for unveiling photoexcited charge transfer, rate-determining steps, and redox reaction barriers are discussed in the context of the work function, electron density difference, Bader charge, and variation in the intermediate adsorption free energy profiles. The activity and mechanism of various photocatalytic redox reactions were elaborately analyzed through in situ characterizations and DFT calculations using representative cases. Finally, the overall photocatalytic redox reactions were summarized with a focus on the construction of an S-scheme heterojunction photocatalyst, reasonable loading of cocatalysts, photo...

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Section: Basic Principles Of Photocatalysismentioning

confidence: 99%

Section: Dft Calculation For Photocatalytic Overall Redox Reactionsmentioning

confidence: 99%

Overall Utilization of Photoexcited Charges for Simultaneous Photocatalytic Redox Reactions

Wang¹,

Wang²,

Zhang³

et al. 2022

Acta Physico Chimica Sinica

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“…To solve the above-mentioned problem and drawback of carrier transmission in conventional heterojunction systems, a novel step-scheme (S-scheme) carrier migration mechanism was first reported by Yu et al The S-scheme heterojunction not only effectively solves the charge transmission and achieves the fast separation, but also preserves the powerful redox abilities and improves the catalytic performance of photocatalytic system [28][29][30] . Up to now, the various S-scheme heterojunctions have been developed and utilized to convert solar energy into usable chemical fuels to decrease the use of fossil fuels, and the Sscheme heterojunctions can also be used to degrade the pollutants to reduce the harmful impact on environment associated with the consumption of fossil fuels (Fig.…”

Section: Introductionmentioning

confidence: 99%

Review of S-Scheme Heterojunction Photocatalyst for H<sub>2</sub>O<sub>2</sub> Production

Zhang¹,

Li²,

Yuan³

et al. 2023

Acta Physico Chimica Sinica

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Rapid industrialization throughout the 20th and 21st centuries has led to the excessive consumption of fossil fuels to satisfy global energy demands. The dominant use of these fuel sources is the main cause of the ever-increasing environmental issues that greatly threaten humanity. Therefore, the development of renewable energy sources is fundamental to solving environmental issues. Solar energy has received widespread attention over the past decades as a green and sustainable energy source. Solar radiation-induced photocatalytic processes on the surface of semiconductor materials are able to convert solar energy into other energy sources for storage and further applications. However, the preparation of highly efficient and stable photocatalysts remains challenging. Recently, a new step-scheme (S-scheme) carrier migration mechanism was reported that solves the drawbacks of carrier migration in conventional heterojunction photocatalysts. The S-scheme heterojunction not only effectively solves the carrier migration problem and achieves fast separation but also preserves the powerful redox abilities and improves the catalytic performance of the photocatalytic system. To date, various S-scheme heterojunctions have been developed and employed to convert solar energy into useful chemical fuels to decrease the reliance on fossil fuels. Furthermore, these systems can also be used to degrade pollutants and reduce the harmful impact on the environment associated with the consumption of fossil fuels, including H2 evolution, pollutant degradation, and the reduction of CO2. H2O2 has been used as an effective, multipurpose, and green oxidizing agent in many applications including pollutant purification, medical disinfection, and chemical synthesis. It has also been used as a high-density energy carrier for fuel cells, with only water and oxygen produced as by-products. Photocatalytic technology provides a low-cost, environmentally friendly, and safe way to produce H2O2, requiring only solar energy, H2O, and O2 gas as raw materials. This paper reviews new S-scheme heterojunction designs for photocatalytic H2O2 production, including g-C3N4-, sulfide-, TiO2-, and ZnO-based S-scheme heterojunctions. The main principles of photocatalytic H2O2 production and the formation mechanism of the S-scheme heterojunction are also discussed. In addition, effective advanced characterization methods for S-scheme heterojunctions have been analyzed. Finally, the challenges that need to be addressed and the direction of future research are identified to provide new methods for the development of high-performance photocatalysts for H2O2 production.

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“…In photocatalysis technology, solar energy is used to drive and excite light catalysts to produce a variety of strong-oxidizing active substances, destroy the molecular structure of pollutants, and finally convert organic pollutants into CO 2 , H 2 O or other pollution-free small molecules, which can be directly discharged into the environment ( Wang et al, 2019 ; Li et al, 2020b ; Li et al, 2022b ; Wang L. et al, 2022 ). Compared with traditional water pollution treatment methods, the photocatalytic degradation method has advantages including a high efficiency, simplicity, a good reproducibility and an easy treatment, which is often used to degrade organic pollutants ( Li et al, 2022a ; Tao et al, 2022 ; Wang W. et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic degradation of tetracycline hydrochloride with g-C3N4/Ag/AgBr composites

et al. 2022

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Graphite carbon nitride (g-C3N4), as a polymer semiconductor photocatalyst, is widely used in the treatment of photocatalytic environmental pollution. In this work, a Z-scheme g-C3N4/Ag/AgBr heterojunction photocatalyst was prepared based on the preparation of a g-C3N4-based heterojunction via in-situ loading through photoreduction method. The g-C3N4/Ag/AgBr composite showed an excellent photocatalytic performance in the degradation of tetracycline hydrochloride pollutants. Among the prepared samples, g-C3N4/Ag/AgBr-8% showed the best photocatalytic ability for the degradation of tetracycline hydrochloride, whose photocatalytic degradation kinetic constant was 0.02764 min−1, which was 9.8 times that of g-C3N4, 2.4 times that of AgBr, and 1.9 times that of Ag/AgBr. In the photocatalytic process, •O2– and •OH are main active oxygen species involved in the degradation of organic pollutants. The photocatalytic mechanism of g-C3N4/Ag/AgBr is mainly through the formation of Z-scheme heterojunctions, which not only effectively improves the separation efficiency of photogenerated electron-hole pairs, but also maintains the oxidation and reduction capability of AgBr and g-C3N4, respectively.

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Solar fuel generation over nature-inspired recyclable TiO2/g-C3N4 S-scheme hierarchical thin-film photocatalyst

Cited by 131 publications

References 53 publications

Overall Utilization of Photoexcited Charges for Simultaneous Photocatalytic Redox Reactions

Overall Utilization of Photoexcited Charges for Simultaneous Photocatalytic Redox Reactions

Review of S-Scheme Heterojunction Photocatalyst for H<sub>2</sub>O<sub>2</sub> Production

Photocatalytic degradation of tetracycline hydrochloride with g-C3N4/Ag/AgBr composites

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