Current Lifetime of Single-Nanoparticle Collision for Sizing Nanoparticles

Abstract

Accurate size analysis of nanoparticles (NPs) is vital for nanotechnology. However, this cannot be realized based on conventional single-nanoparticle collision (SNC) because the current intensity, a thermodynamic parameter of SNC for sizing NPs, is always smaller than the theoretical value due to the effect of NP movements on the electrode surface. Herein, a size-dependent dynamic parameter of SNC, current lifetime, which refers to the time that the current intensity decays to 1/e of the original value, was originally utilized to distinguish differently sized NPs. Results showed that the current lifetime increased with NP size. After taking the current lifetime into account rather than the current intensity, the overlap rates for the peak-type current transients of differently sized Pt NPs (10 and 15 nm) and Au NPs (18 and 35 nm) reduced from 73 and 7% to 45 and 0%, respectively, which were closer to the theoretical values (29 and 0%). Hence, the proposed SNC dynamics-based method holds great potential for developing reliable electrochemical approaches to evaluate NP sizes accurately.

Magnetic Rolling Circle Amplification-Assisted Single-Particle Collision Immunosensor for Ultrasensitive Detection of Cardiac Troponin I

“…From Figure A, the currents were step-shaped rather than peak-shaped, which might be caused by the adhesion of Pt NPs toward the UME surface after the collision. SEM image and initial oxidation potential of N 2 H 4 were characterized to demonstrate the collision process . From the CVs of Au UME before and after the collision, the negative shift of initial potential indicated a better catalytic activity of the UME after collision (Figure B).…”

“…When a single nanoparticle collides with the microelectrode surface by random Brownian motion, it can generate a transient current by hindering electron transfer and self-reaction or catalyzing electroactive substances. − Each effective collision can produce an independent and distinguishable step or peak current. By measuring the current intensity, frequency, current rise time, or life, the size distribution, agglomeration degree, , concentration, electrocatalytic properties, and other properties of NPs in the solution can be directly analyzed in situ . Lemay et al first proposed blocking SPCE to realize electrochemical characterization and measurement of individual insulating particles, which has been regarded as one of the most attractive nanometer-scale analytical methods .…”

Tuning the Electrode Activity to Expose Transformational and Electrocatalytic Characteristics of Individual Nanoparticles by Nanoimpact Electrochemistry

“…Many electrocatalytic reactions have been inspected including the oxygen evolution, [25,26] or reduction, [27,28] hydrogen evolution, [29–33] or oxidation, [34] hydrogen peroxide oxidation [35] and reduction, [36] and hydrazine oxidation reactions [37–39] . Besides, these reactions were inspected at a variety of NPs such as metals (Pd, [29] Pt, [27,30,34,36,37,39] Au, [30,31] ), metal oxides (CoFe 2 O 4 , [25] IrO x, [35] Pt@TiO 2, [28] Ni(OH) 2 [40] ) or carbon materials [24,41,42] . The electrocatalytic activity of a NP is detected by an abrupt increase of the current, the height of which reflects the electrocatalytic efficiency, the dynamics (passivation, etc.…”

“…On the other hand, NIE was employed to determine the electrocatalytic activity of individual NPs. Many electrocatalytic reactions have been inspected including the oxygen evolution, [25,26] or reduction, [27,28] hydrogen evolution, [29–33] or oxidation, [34] hydrogen peroxide oxidation [35] and reduction, [36] and hydrazine oxidation reactions [37–39] . Besides, these reactions were inspected at a variety of NPs such as metals (Pd, [29] Pt, [27,30,34,36,37,39] Au, [30,31] ), metal oxides (CoFe 2 O 4 , [25] IrO x, [35] Pt@TiO 2, [28] Ni(OH) 2 [40] ) or carbon materials [24,41,42] .…”

“…The electrocatalytic activity of a NP is detected by an abrupt increase of the current, the height of which reflects the electrocatalytic efficiency, the dynamics (passivation, etc. ) [30] at the single NP level, [29] or the NP active area [38] …”