Single-Entity Electrocatalysis at Electrode Ensembles Prepared by Template Synthesis

Abstract

Nanoelectrode ensembles (NEEs), prepared by Au template synthesis, are presented as a proof-of-concept sample platform to study individual electrodeposited materials by scanning electrochemical cell microscopy (SECCM). With this platform, the non-conductive membrane support does not contribute to the electrocatalytic activity recorded at each electrode. Use of low-density template membranes results in electrodes that are isolated because initial membrane pores are typically separated by significant (microscale) distances. Electrodeposition of catalytic nanoparticles onto the electrodes of the array and observation of electrocatalytic activity are demonstrated to be suitable for correlative SECCM voltammetric mapping and electron microscopy. Suitability of NEEs for studies of surface Au oxidation, hydrazine oxidation, and hydrogen evolution (hydrogen evolution reaction, HER), and at Pt particles on NEEs (Pt-NEEs) for HER is demonstrated.

The Ionic Composition and Chemistry of Nanopore-Confined Solutions

“…This membrane, called PC 10 , contains 10 ± 2 nm diameter pores (6 × 10 8 pores cm –2 ) running through the 6 μm membrane thickness. The pores were prepared by the well-known track-etch method, − which leaves negatively charged carbonate groups on the pore walls and membrane faces. The charge density has been reported at 2 pmol of carbonate groups per cm 2 , and a corresponding quantity of double-layer cations are present within the pore to balance this negative pore-wall charge.…”

On-Demand Electrochemical Fabrication of Ordered Nanoparticle Arrays using Scanning Electrochemical Cell Microscopy

“…Their fabrication is not trivial, however, and most approaches reported to date require expensive lithographic techniques like optical printing, , plasma etching, photolithography, self-assembly, , electron beam lithography, atomic layer deposition, − soft lithography, , nanosphere lithography, nanoimprint lithography, − and scanning probe lithography . Here, we demonstrate that scanning electrochemical cell microscopy (SECCM) − can be utilized to form well-ordered NP arrays in a powerful, instantly reconfigurable manner. In SECCM, electrolyte-filled pipets are utilized to define nanometer-scale electrochemical interfaces which enable the high-resolution analysis of chemical processes spanning electrocatalysis, − anodic dissolution, , photoelectrochemistry, − ionic transport, and crystallization …”

Unraveling the Structural Sensitivity of CO2 Electroreduction at Facet-Defined Nanocrystals via Correlative Single-Entity and Macroelectrode Measurements

“…To realize the knowledge-guided design of next-generation CO 2 RR electrocatalysts with superior activity, selectivity, and durability, the measurement of intrinsic electrocatalytic parameters at the single-nanocrystal level and comparison with macroelectrode data to establish reliable structure–activity correlations are critical. With such correlations, the impact of extrinsic factors such as electrode morphology, local pH variation, and mass transfer hindrance can be further elucidated. − Scanning electrochemical cell microscopy (SECCM) is especially adept at achieving single-entity electrochemical measurements. − SECCM has been used to resolve the spatial heterogeneity of MoS 2 , and Fe 4.5 Ni 4.5 S 8 catalysts for HER and polycrystalline Au catalysts for CO 2 RR. , SECCM has also been used recently to extract kinetic information for oxygen reduction at Pt electrodes and probing oxygen evolution at superparticles and ZIF-derived composites …”