Iodide‐Induced Fragmentation of Polymerized Hydrophilic Carbon Nitride for High‐Performance Quasi‐Homogeneous Photocatalytic H<sub>2</sub>O<sub>2</sub> Production

Che, Huinan; Gao, Xin; Chen, Juan; Hou, Jun; Ao, Yanhui; Wang, Peifang

doi:10.1002/anie.202111769

Cited by 367 publications

(130 citation statements)

References 51 publications

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“…The formation of different types of oxygenic radicals such as singlet oxygen ( 1 O 2 ) and superoxide anion (O 2 •− ) in a catalytic reaction allows for the control of reaction products, given that these radicals possess unequal redox potentials. [39][40][41] Nonetheless, its usefulness for CH bond activation after an oxygen molecule receives a free electron from an excited photocatalyst remains unclear.…”

Section: Introductionmentioning

confidence: 99%

A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

Xiao

Ruan

et al. 2022

Advanced Materials

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examples is the oxidation of ethylbenzene, yielding acetophenone that is an important raw material for producing medicines, fragrances, cellulose ethers, resins, flavoring agents, and many others. [6][7][8][9] However, the CH bond of ethylbenzene is so strong that its activation and cleavage usually require harsh conditions such as high temperatures. [10][11][12][13][14][15] In general, tert-butyl hydroperoxide or hydrogen peroxide is utilized to create hydroxyl radicals (•OH) with the help of a catalyst. •OH is highly reactive and can easily oxidize ethylbenzene. Nonetheless, the reaction also creates phenethyl alcohol and other byproducts, resulting in reduced selectivity with respect to acetophenone. [16][17][18][19] Given the great utility of this organic compound, it is necessary to develop strategies for improving the reaction selectivity under mild conditions. As a type of sustainable technology, photocatalysis that is able to use solar energy to generate reactive species has already shown tremendous potentials in organic synthesis.Polymeric carbon nitride (CN) as a metal-free photocatalyst has captured widespread attention. [20][21][22][23][24] Under light illumination, free electrons [25][26][27][28] and holes [29][30][31][32] are generated in CN, Selective oxidation of CH bonds is one of the most important reactions in organic synthesis. However, activation of the α-CH bond of ethylbenzene by use of photocatalysis-generated superoxide anions (O 2 •− ) remains a challenge. Herein, the formation of individual Fe atoms on polymeric carbon nitride (CN), that activates O 2 to create O 2 •− for facilitating the reaction of ethylbenzene to form acetophenone, is demonstrated. By utilizing density functional theory and materials characterization techniques, it is shown that individual Fe atoms are coordinated to four N atoms of CN and the resultant low-spin Fe-N 4 system (t 2g 6 e g 0 ) is not only a great adsorption site for oxygen molecules, but also allows for fast transfer of electrons generated in the CN framework to adsorbed O 2 , producing O 2 •− . The oxidation reaction of ethylbenzene triggered by O 2•− ions turns out to have a high conversion rate of 99% as well as an acetophenone selectivity of 99%, which can be ascribed to a novel reaction pathway that is different from the conventional route involving hydroxyl radicals and the production of phenethyl alcohol. Furthermore, it possesses great potential for other CH activation reactions besides ethylbenzene oxidation.

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Section: Introductionmentioning

confidence: 99%

A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

Xiao

Ruan

et al. 2022

Advanced Materials

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“…[10][11][12][13][14] Thus, exploring photocatalysts with high carrier separation efficiency and lightutilization efficiency is the focus of many research workers.Heretofore, countless semiconductors have been used to photocatalytic technology, such as CuIn 5 S 8 , WO 3 , CdS, ZnIn 2 S 4 , g-C 3 N 4 , and so on. [14][15][16][17][18][19][20][21][22] Among these traditional and popular semiconductors, ZnIn 2 S 4 as a low-cost ternary metal sulfide has been applied in photocatalytic reduction of CO 2 field owing to its suitable bandgap, good light resistance, and excellent photoelectric characteristics. [23,24] In addition, compared with independent 1D and 2D, the 3D ZnIn 2 S 4 assembled by ultrathin structures provides superior specific surface area and enriches CO 2 -adsorption sites, thereby improving the ability to anchor CO 2 molecules.…”

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confidence: 99%

NiS Cocatalyst–Modified ZnIn₂S₄ as Ohmic‐Junction Photocatalyst for Efficient Conversion of CO₂

et al. 2022

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Improved photogenerated carrier separation efficiency is of importance for improving photocatalytic activity. Herein, the photocatalytic CO2 reduction of a 3D/0D ZnIn2S4/NiS ohmic‐junction photocatalyst under simulated sunlight is studied. The ZnIn2S4–2%NiS sample has the best excellent photoreduction CO2 performance facilitated by triethanolamine (TEOA) reagents, the ZnIn2S4–2%NiS sample with a CO yield of 12.63 μmol g−1 h−1, which is two times that for pure ZnIn2S4 (6.37 μmol g−1 h−1). It is demonstrated that NiS nanoparticles not only improve the efficiency of electron generation and charge separation by constructing a tight contact ohmic‐junction, but also act as a cocatalyst to extend the photoreaction range and lower the reaction barrier, which effectively accelerates the photocatalytic reduction reaction. Additionally, the 3D structure of ZnIn2S4 has an excellent specific surface area that facilitates the dispersion of NiS. The generation, separation, and migration of photogenerated electron holes are studied from the kinetics perspective through transient photocurrent response, linear sweep voltammetry curve and photoluminescence spectroscopy. In situ Fourier transform infrared spectroscopy is applied to study the CO2 photoreduction process. Herein, the important role of cocatalyst and ohmic‐junction in improving photocatalytic activity is revealed and a new idea for the construction of efficient photocatalysts is provided.

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“…The ineffective hole scavenging via water oxidation and the resulting charge recombination often necessitates the addition of organic electron donors [22,23] . Besides, low selectivity toward H2O2 synthesis via twoelectron O2 reduction compared to the four-electron reduction of O2 or two-electron H2 evolution required manipulating noble metallic sites as cocatalysts to improve both the activity and selectivity of H2O2 production [19,[24][25][26] . However, the excessive addition of sacrificial agents and heavy metal ions not only raises the consumption of raw materials but also increases the subsequent purification difficulty of H2O2 in industrial production, which is more adverse to the development of efficient H2O2 application in life and health field, such as cancer therapy [20,24] .…”

Section: Introductionmentioning

confidence: 99%

Extended Conjugation Refining Carbon Nitride with Thermodynamically Boosted Photocatalytic H2O2 Production and Application for Hypoxic Tumor Therapy

Ma¹,

Peng²,

Ye³

et al. 2022

Preprint

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Artificial photosynthesis offers a promising strategy to efficiently produce hydrogen peroxide (H2O2)-not only an essential industrial chemical but also a promising intermediate product in tumor therapy. However, the rapidly consumed dissolving O2, the competition between oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), and poor activity of water oxidation reaction (WOR) in the photocatalytic processes greatly restrict the efficiency of photocatalytic H2O2 production. In this study, we report a well-defined metal-free C5N2 photocatalyst for efficiently H2O2 production without sacrificial reagents and stabilizers both in normoxic and hypoxic systems. Experimental and computational investigations indicated that the strengthened delocalization of electrons by imine facilitated the formation of electronic structure matching H2O2 production both at the conduction band and valence band in thermodynamics, thus an efficient electron-hole separation and the realistic redox selectivity were successfully enabled. Under simulated solar irradiation, C5N2 achieved an apparent quantum efficiency of 15.4% at 420 nm together with a solar-to-chemical conversion efficiency of 0.55% for H2O2 synthesis, among the best H2O2 production photocatalysts in normoxic systems. More interestingly, due to the dual channels of H2O2 generation, C5N2 could efficiently remove hypoxia restriction and further induce more severe cell damage in photodynamic therapy (PDT). Our findings provided essential insights into the design and synthesis of the dual-channel H2O2 production photocatalysts at the molecular level and would pave more broad applications of photocatalytic H2O2 production.

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Iodide‐Induced Fragmentation of Polymerized Hydrophilic Carbon Nitride for High‐Performance Quasi‐Homogeneous Photocatalytic H₂O₂ Production

Cited by 367 publications

References 51 publications

A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

NiS Cocatalyst–Modified ZnIn₂S₄ as Ohmic‐Junction Photocatalyst for Efficient Conversion of CO₂

Extended Conjugation Refining Carbon Nitride with Thermodynamically Boosted Photocatalytic H2O2 Production and Application for Hypoxic Tumor Therapy

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Iodide‐Induced Fragmentation of Polymerized Hydrophilic Carbon Nitride for High‐Performance Quasi‐Homogeneous Photocatalytic H2O2 Production

Cited by 367 publications

References 51 publications

A Unique Fe–N4 Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

A Unique Fe–N4 Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

NiS Cocatalyst–Modified ZnIn2S4 as Ohmic‐Junction Photocatalyst for Efficient Conversion of CO2

Extended Conjugation Refining Carbon Nitride with Thermodynamically Boosted Photocatalytic H2O2 Production and Application for Hypoxic Tumor Therapy

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Iodide‐Induced Fragmentation of Polymerized Hydrophilic Carbon Nitride for High‐Performance Quasi‐Homogeneous Photocatalytic H₂O₂ Production

A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

NiS Cocatalyst–Modified ZnIn₂S₄ as Ohmic‐Junction Photocatalyst for Efficient Conversion of CO₂