Tareq Al-Attas, Karthick Kannimuthu, Mohd Adnan Khan* and Md Golam Kibria*,
{"title":"通过现场检测反应中间产物揭示电化学甲烷氧化机制","authors":"Tareq Al-Attas, Karthick Kannimuthu, Mohd Adnan Khan* and Md Golam Kibria*, ","doi":"10.1021/acscatal.4c00675","DOIUrl":null,"url":null,"abstract":"<p >The electrochemical partial oxidation of methane (CH<sub>4</sub>) to value-added chemicals under ambient conditions provides a solution for harnessing abundant natural gas resources. Here, we investigate α-Fe<sub>2</sub>O<sub>3</sub> as a model catalyst to gain a mechanistic understanding of the electrochemical CH<sub>4</sub> oxidation reaction (eCH<sub>4</sub>OR). During chronoamperometric experiments, we obtain liquid products (formic acid, acetic acid, and acetone) with ∼6.5% total Faradaic efficiency at 2.3 V versus the reversible hydrogen electrode (V<sub>RHE</sub>). At lower potentials below 2.0 V<sub>RHE</sub>, non-Faradaic CH<sub>4</sub> adsorption occurred, confirmed by in situ ATR-SEIRAS (attenuated total reflectance–surface-enhanced infrared absorption spectroscopy) and impedance spectroscopies. In addition to verifying the presence of the Fe<sup>IV</sup>O species, in situ spectroelectrochemical measurements revealed that CH<sub>4</sub> oxidation initiates via H-abstraction to form •OCH<sub>3</sub> species. The reaction undergoes further oxidation steps, leading to formate. Coupling between •OCH<sub>3</sub> and formate generates •OCOCH<sub>3</sub> species. Further, C–C coupling between – COCH<sub>3</sub> and – CH<sub>3</sub> resulted in acetone formation. Real-time proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS) confirms the proposed pathways. Based on these observations, we propose a mechanistic pathway for selective CH<sub>4</sub> electrooxidation.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":null,"pages":null},"PeriodicalIF":11.3000,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Uncovering Electrochemical Methane Oxidation Mechanism through the In Situ Detection of Reaction Intermediates\",\"authors\":\"Tareq Al-Attas, Karthick Kannimuthu, Mohd Adnan Khan* and Md Golam Kibria*, \",\"doi\":\"10.1021/acscatal.4c00675\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >The electrochemical partial oxidation of methane (CH<sub>4</sub>) to value-added chemicals under ambient conditions provides a solution for harnessing abundant natural gas resources. Here, we investigate α-Fe<sub>2</sub>O<sub>3</sub> as a model catalyst to gain a mechanistic understanding of the electrochemical CH<sub>4</sub> oxidation reaction (eCH<sub>4</sub>OR). During chronoamperometric experiments, we obtain liquid products (formic acid, acetic acid, and acetone) with ∼6.5% total Faradaic efficiency at 2.3 V versus the reversible hydrogen electrode (V<sub>RHE</sub>). At lower potentials below 2.0 V<sub>RHE</sub>, non-Faradaic CH<sub>4</sub> adsorption occurred, confirmed by in situ ATR-SEIRAS (attenuated total reflectance–surface-enhanced infrared absorption spectroscopy) and impedance spectroscopies. In addition to verifying the presence of the Fe<sup>IV</sup>O species, in situ spectroelectrochemical measurements revealed that CH<sub>4</sub> oxidation initiates via H-abstraction to form •OCH<sub>3</sub> species. The reaction undergoes further oxidation steps, leading to formate. Coupling between •OCH<sub>3</sub> and formate generates •OCOCH<sub>3</sub> species. Further, C–C coupling between – COCH<sub>3</sub> and – CH<sub>3</sub> resulted in acetone formation. Real-time proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS) confirms the proposed pathways. Based on these observations, we propose a mechanistic pathway for selective CH<sub>4</sub> electrooxidation.</p>\",\"PeriodicalId\":9,\"journal\":{\"name\":\"ACS Catalysis \",\"volume\":null,\"pages\":null},\"PeriodicalIF\":11.3000,\"publicationDate\":\"2024-06-28\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"ACS Catalysis \",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/acscatal.4c00675\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Catalysis ","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acscatal.4c00675","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Uncovering Electrochemical Methane Oxidation Mechanism through the In Situ Detection of Reaction Intermediates
The electrochemical partial oxidation of methane (CH4) to value-added chemicals under ambient conditions provides a solution for harnessing abundant natural gas resources. Here, we investigate α-Fe2O3 as a model catalyst to gain a mechanistic understanding of the electrochemical CH4 oxidation reaction (eCH4OR). During chronoamperometric experiments, we obtain liquid products (formic acid, acetic acid, and acetone) with ∼6.5% total Faradaic efficiency at 2.3 V versus the reversible hydrogen electrode (VRHE). At lower potentials below 2.0 VRHE, non-Faradaic CH4 adsorption occurred, confirmed by in situ ATR-SEIRAS (attenuated total reflectance–surface-enhanced infrared absorption spectroscopy) and impedance spectroscopies. In addition to verifying the presence of the FeIVO species, in situ spectroelectrochemical measurements revealed that CH4 oxidation initiates via H-abstraction to form •OCH3 species. The reaction undergoes further oxidation steps, leading to formate. Coupling between •OCH3 and formate generates •OCOCH3 species. Further, C–C coupling between – COCH3 and – CH3 resulted in acetone formation. Real-time proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS) confirms the proposed pathways. Based on these observations, we propose a mechanistic pathway for selective CH4 electrooxidation.
期刊介绍:
ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels.
The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.