Changes in the oxidation state of Pt single-atom catalysts upon removal of chloride ligands and their effect for electrochemical reactions

Shin, Sangyong; Kim, Jiwhan; Park, Subin; Kim, Hee Eun; Sung, Yung‐Eun; Lee, Hyunjoo

doi:10.1039/c9cc01593k

Cited by 48 publications

(29 citation statements)

References 39 publications

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“…Our previous work showed that the single atomic Pt catalyst supported on Sb‐doped SnO 2 , in which Pt weight percentage was also 4 wt %, showed very high activity for FAOR of 3.3 A mg Pt −1 at 0.60 V . The oxidation state of supported single atoms can play an essential role for modulating the activity . The Pt single atoms in C@C 3 N 4 ‐4 %Pt showed better FAOR activity while the Pt single‐atoms in C@C 3 N 4 ‐0.5 %Pt or C@C 3 N 4 ‐1 %Pt showed no FAOR activity, because the former has more metallic Pt state while the latter has more oxidic Pt state.…”

Section: Resultsmentioning

confidence: 99%

Palladium Single‐Atom Catalysts Supported on C@C₃N₄ for Electrochemical Reactions

et al. 2019

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Single atom catalysts (SACs) maximize the utilization of noble metal whereas nanoparticle catalysts have inner metal atoms unavailable. In this study, various electrocatalytic reactions were investigated for Pd and Pt SACs. The single atoms were immobilized on thin layers of graphitic carbon nitride with carbon black (for simplicity, C@C3N4) to produce an electrochemically efficient and stable SACs. Single atomic structure was confirmed by high‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and extended X‐ray absorption fine structure (EXAFS) analyses. Oxygen reduction reaction (ORR) and CO stripping experiments were conducted, and the results were compared with the corresponding nanoparticle catalysts. Lack of ensemble sites in the SACs resulted in two‐electron pathway for ORR; single atomic Pd on C@C3N4 (C@C3N4−Pd1) showed high activity and selectivity for H2O2 formation. DFT calculations showed that C@C3N4−Pd1 follows a downhill path for H2O2 formation unlike single atomic Pt on C@C3N4 (C@C3N4‐Pt1), resulting in enhanced H2O2 selectivity. Weaker adsorption of oxygen intermediates on C@C3N4−Pd1 resulted in enhanced ORR activity. The SACs showed no interaction with CO as confirmed by no CO stripping peak. This resulted in no activity for formic acid oxidation following indirect pathway or methanol oxidation, which necessitates COads as reaction intermediates. SACs can be efficient electrocatalysts with high activity and unique selectivity.

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Section: Resultsmentioning

confidence: 99%

Palladium Single‐Atom Catalysts Supported on C@C₃N₄ for Electrochemical Reactions

et al. 2019

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“…Likewise, during the oxygen reduction reaction (ORR) on Pt catalyst surfaces, the Pt sites can be readily covered by various anions, like CN − , F − , Cl − , Br − and I − [23][24][25][26] present in the electrolyte or in the catalyst synthesis medium, with Cl − anions being commonly known for their presence in reference electrodes like the calomel (Hg/Hg 2 Cl 2 ) and Ag/AgCl and are capable of blocking Pt active sites thus hindering the reaction. These anions can be released in the electrolyte due to a concentration gradient near the reference electrode surface which can enhance the escape of such anions from the electrode compartment into the electrolyte in the course of prolonged use.…”

Section: Effect Of Impurities On Electrocatalysismentioning

confidence: 99%

The Effect of Iron Impurities on Transition Metal Catalysts for the Oxygen Evolution Reaction in Alkaline Environment: Activity Mediators or Active Sites?

et al. 2020

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There is an ongoing debate on elucidating the actual role of Fe impurities in alkaline water electrolysis, acting either as reactivity mediators or as co-catalysts through synergistic interaction with the main catalyst material. This perspective summarizes the most prominent oxygen evolution reaction (OER) mechanisms mostly for Ni-based oxides as model transition metal catalysts and highlights the effect of Fe incorporation on the catalyst surface in the form of impurities originating from the electrolyte or co-precipitated in the catalyst lattice, in modulating the OER reaction kinetics, mechanism and stability. Graphic Abstract

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“…Contemporary research on SACs feature atomically dispersed precious metals (<1 wt %) over TMC supports (e. g. TiC, WC, TiN, Mo 2 C, etc. ), where electronically bound atomic metals to promote catalysis with claims of “100 % metal utilization efficiency” [4,5] . A similar application occurs in nanoparticle catalysis, where catalyst NPs are dispersed over TMC supports preventing agglomeration and enabling maximum utilization of nanoparticles .…”

Section: Introductionmentioning

confidence: 99%

Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO₂ Core‐Shell Structures

et al. 2021

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Titanium carbide (TiC) is an attractive support material used in electro‐catalysis and sensing. We report the electrochemistry of TiC nanoparticles (NPs, 35–50 nm in diameter) in different electrolytes in the pH range of 0 to 8. The TiC NPs undergo irreversible oxidation in acidic, basic, and neutral media, attributed to the partial conversion into titanium dioxide (TiO2) with the amount of oxidation highly dependent on the pH of the solution. In H2SO4 (pH 0), multiple voltammetric scans revealed the conversion to be partial but repeated scans allowed a conversion approaching 100 % to be obtained with 20 scans generating a ca 60 % level of oxidation. The process is inferred to lead to the formation of TiC@TiO2 core‐shell nanoparticles (∼12.5 nm core radius and ∼5 nm shell width for a 60 % conversion) and this value sharply decreases with an increase of pH. Independent measurements were conducted at a single NP level (via nano‐impact experiments) to confirm the oxidation of the NPs, showing consistent agreement with the bulk measurements.

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Changes in the oxidation state of Pt single-atom catalysts upon removal of chloride ligands and their effect for electrochemical reactions

Abstract: The activity of Pt single-atom catalysts can be maximized by controlling the oxidation state of the single-atoms.

Cited by 48 publications

References 39 publications

Palladium Single‐Atom Catalysts Supported on C@C₃N₄ for Electrochemical Reactions

Palladium Single‐Atom Catalysts Supported on C@C₃N₄ for Electrochemical Reactions

The Effect of Iron Impurities on Transition Metal Catalysts for the Oxygen Evolution Reaction in Alkaline Environment: Activity Mediators or Active Sites?

Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO₂ Core‐Shell Structures

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Changes in the oxidation state of Pt single-atom catalysts upon removal of chloride ligands and their effect for electrochemical reactions

Abstract: The activity of Pt single-atom catalysts can be maximized by controlling the oxidation state of the single-atoms.

Cited by 48 publications

References 39 publications

Palladium Single‐Atom Catalysts Supported on C@C3N4 for Electrochemical Reactions

Palladium Single‐Atom Catalysts Supported on C@C3N4 for Electrochemical Reactions

The Effect of Iron Impurities on Transition Metal Catalysts for the Oxygen Evolution Reaction in Alkaline Environment: Activity Mediators or Active Sites?

Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO2 Core‐Shell Structures

Contact Info

Product

Resources

About

Palladium Single‐Atom Catalysts Supported on C@C₃N₄ for Electrochemical Reactions

Palladium Single‐Atom Catalysts Supported on C@C₃N₄ for Electrochemical Reactions

Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO₂ Core‐Shell Structures