In situ electrochemical characterisation of graphene and various carbon-based electrode materials: an internal standard approach

We employ an internal standard protocol to simultaneously characterise and utilise electrode materials during their electrochemical implementation. The proposed approach involves 'spiking' a solution containing the analyte of interest (namely, beta-nicotinamide adenine dinucleotide (NADH)) with a common electrochemical redox probe (such as hexaammine-ruthenium(III) chloride), which consequently allows information on the electrochemical properties of the electrode being utilised to be obtained and monitored throughout its application. This approach is explored using a range of commonly encountered carbonaceous electrode materials, including various graphene configurations, such as monolayer, double- and few-layered graphene electrodes - the latter is reported for the first time. The variability in structural quality and stability of the graphene electrodes used (particularly between batches) highlights the necessity for implementation of such approaches within the literature. This work provides a simple, yet effective option for the in situ electrochemical characterisation of various electrode materials, essential where the quality and composition of a 'reported' electrode material can vary greatly depending on its fabrication (batch-to-batch quality) or during the course of experimental use.