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Chao J, Yang X, Zhu Y, Shen J. Oxygen doping regulation of Co single atom catalysts for electro-Fenton degradation of tetracycline. J Colloid Interface Sci 2024; 673:434-443. [PMID: 38878377 DOI: 10.1016/j.jcis.2024.06.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/02/2024] [Accepted: 06/05/2024] [Indexed: 07/26/2024]
Abstract
Electro-Fenton is an effective process for degrading hard-to-degrade organic pollutants, such as tetracycline (TC). However, the degradation efficiency of this process is limited by the activity and stability of the cathode catalyst. Herein, a temperature gradient pyrolysis strategy and oxidation treatment is proposed to modulate the coordination environment to prepare oxygen-doped cobalt monoatomic electrocatalysts (CoNOC). The CoNOC catalysts can achieve the selectivity of 93 % for H2O2 with an electron transfer number close to 2. In the H-cell, the prepared electrocatalysts can achieve more than 100 h of H2O2 production with good stability and the yield of 1.41 mol gcatalyst-1 h-1 with an average Faraday efficiency (FE) of more than 88 %. The calculations indicate that the epoxy groups play a crucial role in modulating the oxygen reduction pathway. The O doping and unique N coordination of Co single-atom active sites (CoN(Pd)3N(Po)1O1) can effectively weaken the O2/OOH* interaction, thereby promoting the production of H2O2. Finally, the electro-Fenton system could achieve a TC degradation rate of 94.9 % for 120 min with a mineralization efficiency of 87.8 % for 180 min, which provides a reliable option for antibiotic treatment. The significant involvement of OH in the electro-Fenton process was confirmed, and the plausible mineralization pathway for TC was proposed.
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Affiliation(s)
- Jiayu Chao
- Shanghai Engineering Research Centre of Hierarchical Nanomaterials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xiaoling Yang
- Shanghai Engineering Research Centre of Hierarchical Nanomaterials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yihua Zhu
- Shanghai Engineering Research Centre of Hierarchical Nanomaterials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.
| | - Jianhua Shen
- Shanghai Engineering Research Centre of Hierarchical Nanomaterials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.
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Li Y, Liu BY, Chen Y, Liu ZF. From 2e- to 4e- pathway in the alkaline oxygen reduction reaction on Au(100): Kinetic circumvention of the volcano curve. J Chem Phys 2024; 160:244705. [PMID: 38916267 DOI: 10.1063/5.0211477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 06/10/2024] [Indexed: 06/26/2024] Open
Abstract
We report the free energy barriers for the elementary reactions in the 2e- and 4e- oxygen reduction reaction (ORR) steps on Au(100) in an alkaline solution. Due to the weak adsorption energy of O2 on Au(100), the barrier for the association channel is very low, and the 2e- pathway is clearly favored, while the barrier for the O-O dissociation channel is significantly higher at 0.5 eV. Above 0.7 V reversible hydrogen electrode (RHE), the association channel becomes thermodynamically unfavorable, which opens up the O-O dissociation channel, leading to the 4e- pathway. The low adsorption energy of oxygenated species on Au is now an advantage, and residue ORR current can be observed up to the 1.0-1.2 V region (RHE). In contrast, the O-O dissociation barrier on Au(111) is significantly higher, at close to 0.9 eV, due to coupling with surface reorganization, which explains the lower ORR activity on Au(111) than that on Au(100). In combination with the previously suggested outer sphere electron transfer to O2 for its initial adsorption, these results provide a consistent explanation for the features in the experimentally measured polarization curve for the alkaline ORR on Au(100) and demonstrate an ORR mechanism distinct from that on Pt(111). It also highlights the importance to consider the spin state of O2 in ORR and to understand the activation barriers, in addition to the adsorption energies, to account for the features observed in electrochemical measurements.
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Affiliation(s)
- Yuke Li
- Department of Chemistry and Centre for Scientific Modeling and Computation, Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Bing-Yu Liu
- Hefei National Research Center for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yanxia Chen
- Hefei National Research Center for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zhi-Feng Liu
- Department of Chemistry and Centre for Scientific Modeling and Computation, Chinese University of Hong Kong, Shatin, Hong Kong, China
- CUHK Shenzhen Research Institute, No. 10, 2nd Yuexing Road, Nanshan District, Shenzhen, China
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Deng M, Wang D, Li Y. General Design Concept of High-Performance Single-Atom-Site Catalysts for H 2O 2 Electrosynthesis. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2314340. [PMID: 38439595 DOI: 10.1002/adma.202314340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/25/2024] [Indexed: 03/06/2024]
Abstract
Hydrogen peroxide (H2O2) as a green oxidizing agent is widely used in various fields. Electrosynthesis of H2O2 has gradually become a hotspot due to its convenient and environment-friendly features. Single-atom-site catalysts (SASCs) with uniform active sites are the ideal catalysts for the in-depth study of the reaction mechanism and structure-performance relationship. In this review, the outstanding achievements of SASCs in the electrosynthesis of H2O2 through 2e- oxygen reduction reaction (ORR) and 2e- water oxygen reaction (WOR) in recent years, are summarized. First, the elementary steps of the two pathways and the roles of key intermediates (*OOH and *OH) in the reactions are systematically discussed. Next, the influence of the size effect, electronic structure regulation, the support/interfacial effect, the optimization of coordination microenvironments, and the SASCs-derived catalysts applied in 2e- ORR are systematically analyzed. Besides, the developments of SASCs in 2e- WOR are also overviewed. Finally, the research progress of H2O2 electrosynthesis on SASCs is concluded, and an outlook on the rational design of SASCs is presented in conjunction with the design strategies and characterization techniques.
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Affiliation(s)
- Mingyang Deng
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Dingsheng Wang
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yadong Li
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
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Kim SG, Kim D, Oh J, Son YJ, Jeong S, Kim J, Hwang SJ. Phosphorus-Ligand Redox Cooperative Catalysis: Unraveling Four-Electron Dioxygen Reduction Pathways and Reactive Intermediates. J Am Chem Soc 2024. [PMID: 38597246 DOI: 10.1021/jacs.4c01748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
The reduction of dioxygen to water is crucial in biology and energy technologies, but it is challenging due to the inertness of triplet oxygen and complex mechanisms. Nature leverages high-spin transition metal complexes for this, whereas main-group compounds with their singlet state and limited redox capabilities exhibit subdued reactivity. We present a novel phosphorus complex capable of four-electron dioxygen reduction, facilitated by unique phosphorus-ligand redox cooperativity. Spectroscopic and computational investigations attribute this cooperative reactivity to the unique electronic structure arising from the geometry of the phosphorus complex bestowed by the ligand. Mechanistic study via spectroscopic and kinetic experiments revealed the involvement of elusive phosphorus intermediates resembling those in metalloenzymes. Our result highlights the multielectron reactivity of phosphorus compound emerging from a carefully designed ligand platform with redox cooperativity. We anticipate that the work described expands the strategies in developing main-group catalytic reactions, especially in small molecule fixations demanding multielectron redox processes.
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Affiliation(s)
- Sung Gyu Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Dongyoung Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Jinrok Oh
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Yeong Jun Son
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Sangmin Jeong
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Joonghan Kim
- Department of Chemistry, The Catholic University of Korea, Bucheon 14662, Republic of Korea
| | - Seung Jun Hwang
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Institute for Convergence Research and Education in Advanced Technology (I-CREATE), Yonsei University, Seoul 03722, Republic of Korea
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Razzaq S, Exner KS. Why efficient bifunctional hydrogen electrocatalysis requires a change in the reaction mechanism. iScience 2024; 27:108848. [PMID: 38313059 PMCID: PMC10837630 DOI: 10.1016/j.isci.2024.108848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/31/2023] [Accepted: 01/04/2024] [Indexed: 02/06/2024] Open
Abstract
Hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) are both two-electron processes that culminate in the formation or consumption of gaseous hydrogen in an electrolyzer or a fuel cell, respectively. Unitized regenerative proton exchange membrane fuel cells merge these two functionalities into one device, allowing to switch between the two modes of operation. This prompts the quest for efficient bifunctional electrode materials catalyzing the HER and HOR with reasonable reaction rates at low overpotentials. In the present study using a data-driven framework, we identify a general criterion for efficient bifunctional performance in the hydrogen electrocatalysis, which refers to a change in the reaction mechanism when switching from cathodic to anodic working conditions. The obtained insight can be used in future studies based on density functional theory to pave the design of efficient HER and HOR catalysts by a dedicated consideration of the kinetics in the analysis of reaction mechanisms.
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Affiliation(s)
- Samad Razzaq
- University Duisburg-Essen, Faculty of Chemistry, Theoretical Inorganic Chemistry, Universitätsstraße 5, 45141 Essen, Germany
| | - Kai S Exner
- University Duisburg-Essen, Faculty of Chemistry, Theoretical Inorganic Chemistry, Universitätsstraße 5, 45141 Essen, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
- Center for Nanointegration (CENIDE) Duisburg-Essen, Duisburg, Germany
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Exner KS. Importance of the Walden Inversion for the Activity Volcano Plot of Oxygen Evolution. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2305505. [PMID: 37904648 PMCID: PMC10754130 DOI: 10.1002/advs.202305505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/25/2023] [Indexed: 11/01/2023]
Abstract
Since the birth of the computational hydrogen electrode approach, it is considered that activity trends of electrocatalysts in a homologous series can be quantified by the construction of volcano plots. This method aims to steer materials discovery by the identification of catalysts with an improved reaction kinetics, though evaluated by means of thermodynamic descriptors. The conventional approach for the volcano plot of the oxygen evolution reaction (OER) relies on the assumption of the mononuclear mechanism, comprising the * OH, * O, and * OOH intermediates. In the present manuscript, two new mechanistic pathways, comprising the idea of the Walden inversion in that bond-breaking and bond-making occurs simultaneously, are factored into a potential-dependent OER activity volcano plot. Surprisingly, it turns out that the Walden inversion plays an important role since the activity volcano is governed by mechanistic pathways comprising Walden steps rather than by the traditionally assumed reaction mechanisms under typical OER conditions.
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Affiliation(s)
- Kai S. Exner
- Faculty of ChemistryTheoretical Inorganic ChemistryUniversity Duisburg‐EssenUniversitätsstraße 545141EssenGermany
- Cluster of Excellence RESOLV44801BochumGermany
- Center for Nanointegration (CENIDE) Duisburg‐Essen47057DuisburgGermany
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Exner KS. On the mechanistic complexity of oxygen evolution: potential-dependent switching of the mechanism at the volcano apex. MATERIALS HORIZONS 2023; 10:2086-2095. [PMID: 36928519 DOI: 10.1039/d3mh00047h] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The anodic four-electron oxygen evolution reaction (OER) corresponds to the limiting process in acidic or alkaline electrolyzers to produce gaseous hydrogen at the cathode of the device. In the last decade, tremendous efforts have been dedicated to the identification of active OER materials by electronic structure calculations in the density functional theory approximation. Most of these works rely on the assumption that the mononuclear mechanism, comprising the *OH, *O, and *OOH intermediates, is operative under OER conditions, and that a single elementary reaction step (most likely *OOH formation) governs the kinetics. In the present manuscript, six different OER mechanisms are analyzed, and potential-dependent volcano curves are constructed to comprehend the electrocatalytic activity of these pathways in the approximation of the descriptor Gmax(U), a potential-dependent activity measure based on the notion of the free-energy span model. While the mononuclear description mainly describes the legs of the volcano plot, corresponding to electrocatalysts with low intrinsic activity, it is demonstrated that the preferred pathway at the volcano apex is a strong function of the applied electrode potential. The observed mechanistic complexity including a switch of the favored pathway with increasing overpotential sets previous investigations aiming at the identification of reaction mechanisms and limiting steps into question since the entire breadth of OER pathways was not accounted for. A prerequisite for future atomic-scale studies on highly active OER catalysts refers to the evaluation of several mechanistic pathways so that neither important mechanistic features are overlooked nor limiting steps are incorrectly determined.
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Affiliation(s)
- Kai S Exner
- University Duisburg-Essen, Faculty of Chemistry, Theoretical Inorganic Chemistry, Universitätsstraße 5, 45141 Essen, Germany.
- Cluster of Excellence RESOLV, 44801 Bochum, Germany
- Center for Nanointegration (CENIDE) Duisburg-Essen, 47057 Duisburg, Germany
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Exner KS. Toward data‐ and mechanistic‐driven volcano plots in electrocatalysis. ELECTROCHEMICAL SCIENCE ADVANCES 2023. [DOI: 10.1002/elsa.202200014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- Kai S. Exner
- Faculty of Chemistry Theoretical Inorganic Chemistry University Duisburg‐Essen Essen Germany
- Cluster of Excellence RESOLV Bochum Germany
- Center for Nanointegration (CENIDE) Duisburg‐Essen Duisburg Germany
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