From Ensemble Electrochemistry to Nano‐Impact Electrochemistry: Altered Reaction Selectivity

Abstract

Selective electrochemical production of valued chemicals is of significant importance but remains a great challenge in chemistry. Conventional approaches for enhancing reaction selectivity focus on the improvement of the catalysts themselves. In this work, we systematically studied the reaction kinetics and mass transport behavior of LaNiO 3 nanocubes (LaNiO 3 NCs) catalyzed hydrogen peroxide reduction reaction (HPRR) at ensemble and single nanoparticle levels using nano-impact electrochemistry (NIE). We find that the selectivity of HPRR was altered at individual random-walk nanoparticles as compared to their ensemble counterpart without changing the reaction kinetics, due to the significantly enhanced mass transport at single nanoparticles. This discovery offers the scope of new catalytic approaches for engineering electrochemical reactions in general.

Nano‐Impact Electrochemistry Reveals Kinetics Information of Metal‐Ion Battery Materials with Multiple Redox Centers

“…[8] NIE offers a wealth of information, such as collision frequency, current shape and height, etc., that enables researchers to uncover intrinsic properties of the electrochemical processes occurring within nano-confined domains. [9] Compared with immobilized single-particle analysis, [10] NIE demonstrates a much faster sampling rate, indicating significant potential in high-throughput analysis. Owing to these advantages, NIE has been employed to investigate the kinetic processes of individual active materials in MIBs, [11] including LiMn 2 O 4 , [12] LiFePO 4 , [13] LiCoO 2 , [14] LiNi 0.8 Co 0.1 Mn 0.1 O 2 , [15] and more.…”

Redox Electrochemistry of Mn(II) via Carbon Black Nanoparticle Impacts

“…Here, we assume that during impacts, the metal is reduced onto the particle itself; however, when the working electrode and particles are the same material (e.g., carbon), competition can occur between these two materials, and there is a possibility of metal ions being reduced/oxidized on the electrode surface during “impact”. Analysis of the resulting transient signals can determine a range of information including nanoparticle size, concentration, and charge transfer kinetics of a system. − In the context of metal recovery, there are few reports concerning the electrodeposition of metals using nanoimpact electrochemistry, and until recently, these were limited to metal nanoparticle cores only. − More recently, the electrodeposition of copper onto fly-ash cenospheres and palladium on carbon black has been reported as well as the rapid screening of bimetallic catalysts. ,, …”

Unveiling the Solvent Effect in Plasmon Enhanced Electrochemistry via the Nanoparticle-Impact Technique

“…Nanoparticle impact electrochemistry (NIE) is a recently progressed electrochemical method, which is based on the stochastic collisions of individual nanoparticles onto an inert microelectrode from Brownian motion (Figure , right). − NIE has enabled researchers to uncover intrinsic information about electrochemical processes that occur in nanoconfined domains, which can be obscured by averaging measurements in ensemble electrochemistry. − Unlike nanoparticle-modified macroelectrodes, where extracting the electron-transfer rate can be challenging due to the influence of mass transport and electrode modification, − NIE simplifies the determination of electron-transfer rates due to a much improved mass-transport condition created at the single-nanoparticle level. ,, Therefore, NIE can be used in conjunction with microscopic electron-transfer models, such as the Marcus–Hush (MH) theory, to identify the kinetics attributed to the variation of the electrochemical signal caused by PEEC. This combination allows for the discovery of new mechanisms for electrochemical reactions that would remain hidden in macroscopic ensemble measurements.…”

“…28−31 Unlike nanoparticle-modified macroelectrodes, where extracting the electron-transfer rate can be challenging due to the influence of mass transport and electrode modification, 32−34 of electron-transfer rates due to a much improved masstransport condition created at the single-nanoparticle level. 27,35,36 Therefore, NIE can be used in conjunction with microscopic electron-transfer models, such as the Marcus− Hush (MH) theory, to identify the kinetics attributed to the variation of the electrochemical signal caused by PEEC. This combination allows for the discovery of new mechanisms for electrochemical reactions that would remain hidden in macroscopic ensemble measurements.…”