Measuring the Pseudocapacitive Behavior of Individual V₂O₅ Particles by Scanning Electrochemical Cell Microscopy

Abstract

V 2 O 5 is a promising pseudocapacitive material for electrochemical energy storage with balanced power and energy density. Understanding the charge-storage mechanism is of significance to further improve the rate performance. Here, we report an electrochemical study of individual V 2 O 5 particles using scanning electrochemical cell microscopy with colocalized electron microscopy. A carbon sputtering procedure is proposed for the pristine V 2 O 5 particles to improve their structure stability and electronic conductivity. The achieved high-quality electrochemical cyclic voltammetry results, structural integrity, and high oxidation to reduction charge ratio (as high as 97.74%) assured further quantitative analysis of the pseudocapacitive behavior of single particles and correlation with local particle structures. A broad range of capacitive contribution is revealed, with an average ratio of 76% at 1.0 V/s. This study provides new opportunities for quantitative analysis of the electrochemical charge-storage process at single particles, especially for electrode materials with electrolyte-induced instability.

Drop-cast gold nanoparticles are not always electrocatalytically active for the borohydride oxidation reaction

“…52 It is proposed that the presence of a shifted a 2 peak at approximately 0.5 V vs. SCE is due to the removal of absorbed species on the AuNP, and oxidation of the surface, which subsequently becomes active for the BOR on further cycling of the potential. 52–54…”

“…52 It is proposed that the presence of a shied a 2 peak at approximately 0.5 V vs. SCE is due to the removal of absorbed species on the AuNP, and oxidation of the surface, which subsequently becomes active for the BOR on further cycling of the potential. [52][53][54] In all cases, the successive cycles (in red, green, and blue) show a gradual increase in BOR activity, as the AuNP surface continues to undergo gradual electrochemical cleaning and/or surface restructuring due to the formation/stripping of oxide layers. 55 This is crucial for those wishing to study single entities, as these particles already underwent 10 cycles of electrochemical cleaning (via macroscale electrochemistry, see ESI, S1.2 †), yet still do not display a steady (i.e.…”

Recent Developments in Single-Entity Electrochemistry

“…A trend in SEE with SECCM is the study of single nanocrystals with controlled size, shape, facet, and surface area. ,− Jeong et al employed SECCM to resolve activity for electrochemical CO 2 reduction (eCO 2 RR) at faceted single-crystalline Au nanocrystals . Three differently faceted nanocrystals were designed to have the same surface area.…”

Five years of scanning electrochemical cell microscopy (SECCM): new insights and innovations

“…Gao et al utilised identical-location SECCM and SEM to study pseudocapacitive charge storage in single microparticles of vanadia (V 2 O 5 ) in aqueous LiCl electrolyte. 130 i – E measurements on pristine V 2 O 5 particles gave rise to voltammograms with poorly resolved peaks and a very low reduction (charge) to oxidation (discharge) charge ratio, indicating poor cycling performance. In addition, the i – E curves exhibited significant current fluctuations during measurement ( e.g.…”