Quantification of Active Site Density and Turnover Frequency: from Single-Atom Metal to Nanoparticle Electrocatalysts

Title
Quantification of Active Site Density and Turnover Frequency: from Single-Atom Metal to Nanoparticle Electrocatalysts
Authors
오형석배근수김해솔최한솔정평화김동현권한창이국성최민희Frederic Jaouen최창혁
Keywords
Single-atom catalysts; Fe?N?C catalysts; active site density; turnover frequency; oxygen reduction reaction
Issue Date
2021-04
Publisher
JACS Au
Citation
VOL 1, NO 3, 온라인게재
Abstract
Single-atom catalysts (SACs) featuring atomically dispersed metal cations covalently embedded in a carbon matrix show significant potential to achieve high catalytic performance in various electrocatalytic reactions. Although considerable advances have been achieved in their syntheses and electrochemical applications, further development and fundamental understanding are limited by a lack of strategies that can allow the quantitative analyses of their intrinsic catalytic characteristics, that is, active site density (SD) and turnover frequency (TOF). Here we show an in situ SD quantification method using a cyanide anion as a probe molecule. The decrease in cyanide concentration triggered by irreversible adsorption on metal-based active sites of a model Fe?N?C catalyst is precisely measured by spectrophotometry, and it is correlated to the relative decrease in electrocatalytic activity in the model reaction of oxygen reduction reaction. The linear correlation verifies the surface-sensitive and metal-specific adsorption of cyanide on Fe?Nx sites, based on which the values of SD and TOF can be determined. Notably, this analytical strategy shows versatile applicability to a series of transition/noble metal SACs and Pt nanoparticles in a broad pH range (1?13). The SD and TOF quantification can afford an improved understanding of the structure?activity relationship for a broad range of electrocatalysts, in particular, the SACs, for which no general electrochemical method to determine the intrinsic catalytic characteristics is available.
URI
http://pubs.kist.re.kr/handle/201004/73066
ISSN
2691-3704
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KIST Publication > Article
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