AFM Studies of Metal Deposition: Instantaneous Nucleation and the Growth of Cobalt Nanoparticles on Boron‐Doped Diamond Electrodes

Abstract

In situ atomic force microscopy (AFM) is used to study the growth of cobalt nuclei on a boron doped diamond electrode under potentiostatic control. The rate of growth of the nuclei at the electrode surface is monitored using AFM as a function of time at different deposition potentials. The nucleation of cobalt nuclei is found to be "instantaneous" and the growth of the nuclei is shown to be kinetically rather than diffusionally controlled over periods of tens and hundreds of seconds. At very short times (<10 seconds) the kinetics of nucleation are apparent.

Metal Nanoparticle Modified Boron Doped Diamond Electrodes for Use in Electroanalysis

“…The deposition of lead metal [48] in 2002 utilised novel in situ EC-AFM techniques to observe the nucleation and growth of the lead nuclei over a series of deposition intervals. A similar investigation into the deposition and growth of cobalt nanoparticles on BDD electrodes was conducted in 2006 by Simm et al [46]. EC-AFM images of the cobalt modification taken from [46] (with permission) are shown in Figure 2.…”

“…A similar investigation into the deposition and growth of cobalt nanoparticles on BDD electrodes was conducted in 2006 by Simm et al [46]. EC-AFM images of the cobalt modification taken from [46] (with permission) are shown in Figure 2.…”

“…The fabrication of a nanoparticle array, whether random or intentional, leads to the diffusional domains illustrated in Figure 1. The figure specifically illustrates what would occur at a nanoparticle modified BDD electrode with metal deposits rather than implanted ions, the latter with a system more akin to that referred to in the paper by Simm et al [46]. Four regimes of behaviour emerge; 2. slower scan rate yet the coverage is still low and therefore the isolated nanoparticles show independent, convergent diffusion and therefore steady state behaviour, 3. increased surface coverage leading to mixed convergent and planar diffusion as partial overlap of diffusion zones with neighbouring nanoparticles occurs, 4. scan rates and coverage in which there is complete overlap of diffusion domains and therefore planar diffusion across the whole nanoparticle assembly so that a cyclic voltammetric response is generated, characteristic of the area of the entire electrode, not the nanoparticle surface area.…”

“…Controlled growth of nanoparticles is becoming increasingly easier with the advent of improved surface characterization techniques such as scanning electron microscopy (SEM) and atomic force microscopy (AFM). The latter is of particular use in recent years, as in situ AFM has greatly developed and electrochemical AFM techniques have vastly improved [14,46,48]. This is consequently allowing the immediate imaging of electrodes post deposition, without removal from the deposition solution and potentially changing the surface conditions, thus allowing the characterization of nanoparticle modified electrode surfaces in their as-deposited analytical state.…”

Nucleation and growth of thin nickel layers under the influence of a magnetic field

“…Although on the cathode several active sites may be available [28,29], not all of them will be converted into nuclei at a given potential, as they may have different activation energies for nucleation [27,30]. This aspect has been discussed extensively in the literature (nucleation rate dispersion) but here we will pursue a phenomenological approach based on the widely used first order rate expression for nucleation, N(t) = N 0 [1 À exp(ÀAt)] [16].…”