Visualization of Hydrogen Evolution at Individual Platinum Nanoparticles at a Buried Interface

Abstract

Electrochemical processes occurring at solid/solid and solid/membrane interfaces govern the behavior of a variety of energy storage devices, including electrocatalytic reactions at electrode/membrane interfaces in fuel cells and ion insertion at electrode/electrolyte interfaces in solid-state batteries. Due to the heterogeneity of these systems, interrogation of interfacial activity at nanometer length scales is desired to understand system performance, yet the buried nature of the interfaces makes localized activity inaccessible to conventional electrochemical techniques. Herein, we demonstrate nanoscale electrochemical imaging of hydrogen evolution at individual Pt nanoparticles (PtNPs) positioned at a buried interface using scanning electrochemical cell microscopy (SECCM). Specifically, we image the hydrogen evolution reaction (HER) at individual carbon-supported PtNP electrocatalysts covered by a 100 to 800 nm thick layer of the proton exchange membrane Nafion. The rate of hydrogen evolution at PtNP at this buried interface is shown to be a function of Nafion thickness, with the highest activity observed for ∼200 nm thick films.

Engineering Catalyst Layers for Next‐Generation Polymer Electrolyte Fuel Cells: A Review of Design, Materials, and Methods

“…For example, 60 nm films have been reported to have lower proton resistance than 42 nm films, and 200 nm films have been observed to have greater through‐plane proton conductivity than both thinner and thicker layers. [ 233 ] This is likely an effect of the differing nanostructures and suggests that reducing the ionomer content in the CL to minimize proton resistance will only be successful if the covering ionomer films are homogenously maintained at ≈10 nm, rather than the heterogeneous layering commonly observed with areas <10 nm and >50 nm.…”

Large‐Scale Synthesis of Functionalized Nanowires to Construct Nanoelectrodes for Intracellular Sensing

“…[1d,e,2] Fore xample,n anoelectrodes provide au seful avenue to precisely reveal the relationship between the functionality (catalytic activity) of nanoparticles and their structures (e.g., size,shape and crystal structure) at as ingle-nanoparticle level to avoid ensemble averaging. [3] Especially in the field of biological applications, endowed with the nano-size and high spatiotemporal solution, nanoelectrode electrochemistry presents exceptional superiority in exploring subcellular biological processes (e.g., intracellular events [4] and single synapse behavior [5] )w hile well maintaining cell vitality.Further incorporating with other techniques such as scanning electrochemical microscopy, atomic force microscopy and scanning ion-conductance microscopy,n anoelectrochemistry provides am ore comprehensive tool to simultaneously acquire both electrochemical and topographical information. [2,6] So far, several common strategies have been developed for nanoelectrode fabrication.…”

Scanning electrochemical cell microscopy for the study of (nano)particle electrochemistry: From the sub‐particle to ensemble level

“…In addition, the overall HER rate was shown to be a function of membrane thickness, with the highest apparent activity observed with ≈200 nm thick films, attributed to a complex balance between the concentration and mobility of H + in the aqueous solution within the SECCM probe ([H + ] = 0.025 M; relatively high H + mobility) relative to the Nafion membrane ([H + ] ≈ 1 M; relatively low H + mobility; water content dependent). [ 52 ]…”