Nano Impact Electrochemistry: Effects of Electronic Filtering on Peak Height, Duration and Area

Abstract

What was the biggest surprise?When analyzingt he currentr esponse of commercial potentiostats, we realized that most of them employ surprisingly strong low pass filtering. This is usually appropriate in electrochemistry.H owever, in nanoimpact studies, currents ignals of low amplitude ( nA) and short duration ( ms) are concerned. Hence, shape and duration of collision peaks may be significantly altered, which may causem isinterpretationo fr eaction mechanisms and extraction of incorrect kinetic information.Invited for this month'sc over picturei st he group of Prof. Dr.K ristinaT schulik from Ruhr University Bochum( Germany). The cover picture shows the alteration of ac urrent signal caused by the electronic filtering implemented in potentiostats. These filter effects are uncovereda nd as imple method is provided for electrochemists to test and validate their experimental setup. This is particularly important for transients ingle-entity electrochemistry,w hich requires low current measurements at high time resolution. Read the full text of the Articleat10.1002/celc.201800738.

Fast electrodeposition of zinc onto single zinc nanoparticles

“…This method consists in dispersing a small amount of particles in solution, which, by virtue of their Brownian motion, may collide with the surface of a microelectrode. The microelectrode is polarised at a potential such that the stochastic collisions of the nanoparticles result in spikes in the background current recorded at the microelectrode [26,[33][34][35][36][37][38]. The magnitude of the charge, duration, and frequency of a numerically relevant number of single collision events can be analysed statistically in order to harvest information on the reactions occurring at the nanoscale [28-30, 32, 38, 39].…”

Optimización de un dispositivo portátil de detección de nanopartículas

“…Using this filter adds an additional benefit: the cutoff frequency allows modifying the length or width of the current spike. By changing signal length, amplitude varies too, preserving the area under the curve, which allows to continue obtaining the nanoparticle's size [12]. .…”

“…Change in the current spike when using different cutoff frequencies in the low-pass filter. Source: [12].…”

Advanced Nanoscale Approaches to Single-(Bio)entity Sensing and Imaging

“…Although the use of macroelectrodes to detect nanoimpact events has been reported [235,236], nano/microelectrodes could be more appropriate since they can be used for the study of fast electron transfers (mass transfer is enhanced at these scales), capacitive currents are small and they would also reduce the probability to multi-nanoparticle impacts, which could complicate the analysis of signals [237]. It is also worth to mention that the employed instrumentation plays an important role to get appropriate signals and the use of suitable electronic filters is important [238]. Since there is a growing demand for reliable, high-throughput and miniaturised technologies for single-entity studies, the nanoimpact method has been implemented in areas as diverse as electrocatalysis, materials science, bioelectrochemistry and (bio)sensing [233,239].…”