Stochastic detection and characterisation of individual ferrocene derivative tagged graphene nanoplatelets

Graphene nanoplatelets (GNPs) are ‘tagged’ with 1-(biphen-4-yl)ferrocene. Chronoamperometry is then utilised to observe single particle impacts when GNPs suspended in solution collide with a carbon fibre micro wire electrode held at an oxidising potential, resulting in current/time transient “spikes”. The impacts are associated with two types of charge transfer: Faradaic due to oxidation of the ‘tag’ and capacitative due to disruption of the double layer. Analysis of the spikes suggests approximate monolayer coverage of 1-(biphen-4-yl)ferrocene on the GNP surfaces, with a surface coverage of (2.2 ± 0.3) × 10−10 mol cm−2. In contrast non-derivatised ferrocene does not exhibit any significant adsorption on the GNP material.