Electrodeposition of Isolated Platinum Atoms and Clusters on Bismuth—Characterization and Electrocatalysis

Abstract

We describe a method for the electrodeposition of an isolated single Pt atom or small cluster, up to 9 atoms, on a bismuth ultramicroelectrode (UME). This deposition was immediately followed by electrochemical characterization via the hydrogen evolution reaction (HER) that occurs readily on the electrodeposited Pt but not on Bi. The observed voltammetric current plateau, even for a single atom, which behaves as an electrode, allows the estimation of deposit size. Pt was plated from solutions of femtomolar PtCl, which allowed precise control of the arrival of ions and thus the plating rate on the Bi UME, to one ion every few seconds. This allowed the atom-by-atom fabrication of isolated platinum deposits, ranging from single atoms to 9-atom clusters. The limiting currents in voltammetry gave the size and number of atoms of the clusters. Given the stochasticity of the plating process, we show that the number of atoms plated over a given time (10 and 20 s) follows a Poisson distribution. Taking the potential at a certain current density as a measure of the relative rate of the HER, we found that the potential shifted positively as the size increased, with single atoms showing the largest overpotentials compared to bulk Pt.

The Multifaceted Reactivity of Single‐Atom Heterogeneous Catalysts

“…[5] These have mainly focused on Pt-based catalysts, [55,[114][115][116][117] because their established practical relevance,o ra lternatives based on earth-abundant metals (primarily Co or Fe). [5] These have mainly focused on Pt-based catalysts, [55,[114][115][116][117] because their established practical relevance,o ra lternatives based on earth-abundant metals (primarily Co or Fe).…”

“…In the majority of cases,t he performance of SACs has been evaluated with respect to the commercial Pt/C NP-based catalyst. [116] While strong correlations were evident, no complementary characterization data was provided to confirm the speciation or stability.Inthe case of other metals, and despite promising observations,t he comparative performance of NPs has not been explored. Significantly enhanced activity has been reported in the hydrogen evolution reaction (HER) over pseudo-SACs based on N-doped graphene nanosheets (37 times) [55] or single-walled carbon nanotubes (up to 333 times) [114] in acidic media.…”

A New Generation of Platinum‐Copper Electrocatalysts with Ultra‐Low Concentrations of Platinum for Oxygen‐Reduction Reactions in Alkaline Media

“…The n value is ∼4.0, indicating that the O 2 is reduced into H 2 O completely without any production of intermediates. n value manifests that the as‐prepared Pt−Cu NPs are promising ORR catalysts . The accelerating durability tests (ADTs) of the electrocatalysts are critical for their large‐scale implementation in fuel cells .…”

“…n value manifests that the as-prepared PtÀ Cu NPs are promising ORR catalysts. [40,41] The accelerating durability tests (ADTs) of the electrocatalysts are critical for their large-scale implementation in fuel cells. [42][43][44] CV-ADTs of Pt 0.25 Cu and Pt/C were analyzed for 1000 cycles, and then LSV recorded at 1600 rpm ( Figure 5).…”

Underpotential Deposition of Copper Clusters on Sulfur and Nitrogen Co‐Doped Graphite Foam for the Oxygen Reduction Reaction

“…[14][15][16][17] This technique offers more opportunities for the control over the size and morphology of the deposited nanostructures via tuning the applied potential, time duration and electrolyte composition. [18,19] However, further downsizing the deposited metal NPs and narrow their size distribution remains challenging. In detail, electrodeposition of metal substances is realized by so-called overpotential deposition (OPD), following Volmer-Weber 3D island growth mechanism.…”