Precision ChemistryPub Date : 2025-01-08DOI: 10.1021/prechem.4c0008110.1021/prechem.4c00081
Er-Fei Zhen, Bing-Yu Liu, Meng-Ke Zhang, Lu−Lu Zhang, Chen-Yu Zhang, Jun Cai, Marko M. Melander, Jun Huang* and Yan-Xia Chen*,
{"title":"Disentangling Multiple pH-Dependent Factors on the Hydrogen Evolution Reaction at Au(111)","authors":"Er-Fei Zhen, Bing-Yu Liu, Meng-Ke Zhang, Lu−Lu Zhang, Chen-Yu Zhang, Jun Cai, Marko M. Melander, Jun Huang* and Yan-Xia Chen*, ","doi":"10.1021/prechem.4c0008110.1021/prechem.4c00081","DOIUrl":"https://doi.org/10.1021/prechem.4c00081https://doi.org/10.1021/prechem.4c00081","url":null,"abstract":"<p >Understanding how the electrolyte pH affects electrocatalytic activity is a topic of crucial importance in a large variety of systems. However, unraveling the origin of the pH effects is complicated often by the fact that both the reaction driving forces and reactant concentrations in the electric double layer (EDL) change simultaneously with the pH value. Herein, we employ the hydrogen evolution reaction (HER) at Au(111)-aqueous solution interfaces as a model system to disentangle different pH-dependent factors. In 0.1 M NaOH, the HER current density at Au(111) in the potential range of −0.4 V < <i>E</i><sub>RHE</sub> < 0 V is up to 60 times smaller than that in 0.1 M HClO<sub>4</sub>. A reaction model with proper consideration of the local reaction conditions within the EDL is developed. After correcting for the EDL effects, the rate constant for HER is only weakly pH-dependent. Our analysis unambiguously reveals that the observed pH effects are mainly due to the pH-dependent reorganization free energy, which depends on the electrostatic potential and the local reaction conditions within the EDL. Possible origins of the pH and temperature dependence of the activation energy and the electron transfer coefficients are discussed. This work suggests that factors influencing the intrinsic pH-dependent kinetics are easier to understand after proper corrections of EDL effects.</p>","PeriodicalId":29793,"journal":{"name":"Precision Chemistry","volume":"3 3","pages":"135–148 135–148"},"PeriodicalIF":0.0,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/prechem.4c00081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143675855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Boosting Turnover in the Triarylborane-Catalyzed Hydrogenation of <i>N</i>-Substituted Indoles via Olefin-to-Nitrogen Lewis Base Switching in H<sub>2</sub>-Cleavage Steps.","authors":"Taiki Hashimoto, Masakazu Tanigawa, Kimitaka Kambe, Sensuke Ogoshi, Yoichi Hoshimoto","doi":"10.1021/prechem.4c00090","DOIUrl":"10.1021/prechem.4c00090","url":null,"abstract":"<p><p>The shelf-stable heteroleptic borane B(2,6-Cl<sub>2</sub>C<sub>6</sub>H<sub>3</sub>)(3,5-Br<sub>2</sub>-2,6-F<sub>2</sub>C<sub>6</sub>H)<sub>2</sub> (<b>B</b> <sup><b>7</b></sup> ) efficiently catalyzes the solvent-free hydrogenation of various substituted indoles to indolines with an unprecedented turnover number of 8,500, which is more than 400-fold higher than that reported for B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> under diluted conditions. Mechanistic studies revealed that this hydrogenation proceeds via an olefin-to-nitrogen switching of Lewis bases involved in the H<sub>2</sub>-cleavage steps: initially, H<sub>2</sub> cleavage is mediated by a frustrated Lewis pair (FLP) comprising the indole C3-carbon and boron atoms, which then switches to an FLP system comprising the indoline nitrogen and boron atoms after formation of the indoline. This study demonstrates the potential of relatively benign main-group elements for the catalytic synthesis of valuable N-containing molecules using H<sub>2</sub>.</p>","PeriodicalId":29793,"journal":{"name":"Precision Chemistry","volume":"3 3","pages":"128-134"},"PeriodicalIF":0.0,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11938162/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143731911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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