Nanomaterials on the electrode: why graphene, MXenes and metal nanoparticles boost sensitivity

Two electrodes can look identical to the eye and still give very different signals. Much of the difference lies at the nanoscale. By coating the working electrode with nanomaterials such as graphene, MXenes or metal nanoparticles, electrochemists can make the same molecule produce a larger, sharper and more reproducible signal.

Why the surface matters

An electrochemical signal is generated only where the molecule meets the electrode. A useful analogy is a car park: a flat car park holds a limited number of cars, but a multi-storey car park on the same footprint holds many more. Nanomaterials do something similar for electrodes, and they add a few extra benefits:

• Larger active surface area: more sites where the target can react or adsorb, and more room to attach recognition elements.

• Faster electron transfer: highly conductive materials help electrons move quickly between the molecule and the electrode.

• Electrocatalytic effects: some materials lower the potential needed for a reaction (the overpotential) and make peaks sharper and easier to separate from interferences.

Three families of nanomaterials

1. Graphene and related carbons: graphene is a single layer of carbon atoms arranged in a honeycomb lattice. Graphene, graphene oxide and reduced graphene oxide combine high surface area with good conductivity and are widely used in electrochemical sensors and biosensors.

2. MXenes and MBenes: MXenes are two-dimensional transition metal carbides, nitrides and carbonitrides, first used in an electrochemical sensor in 2014. Their conductivity and surface chemistry make them attractive electrode modifiers. MBenes are related two-dimensional transition metal borides and are a newer, still emerging class.

3. Metal nanoparticles: gold, silver and platinum nanoparticles are the most popular. They improve conductivity and catalytic activity and offer a good surface for immobilising biomolecules, alone or decorated on carbon nanomaterials.

Schematic, not to scale: graphene (honeycomb lattice) decorated with gold nanoparticles, with layered MXene flakes behind.

In practice, these materials are often combined. A hybrid of a 2D material and metal nanoparticles can join the large area and conductivity of one with the catalytic activity of the other. More signal is not automatically better, though: the modified surface must be characterised carefully, deposited reproducibly and checked for stability and background current.

Key takeaways

• Nanomaterials increase the active area and speed up electron transfer at the electrode.

• Graphene, MXenes/MBenes and metal nanoparticles each bring different strengths, and hybrids combine them.

• A good nanomaterial-modified sensor is sensitive and reproducible, not only high in signal.

Nanomaterials at SAOnS Lab

At SAOnS Lab, we use nanomaterials to build more sensitive electrochemical sensors for drugs and biomarkers, often in combination with molecularly imprinted polymers for selectivity. Our group has recently reviewed recent advances in MXene–molecularly imprinted polymer hybrid nanocomposites for the electrochemical detection of pandemic-related biomarkers (Shahzad et al., 2026).

Which nanomaterial has worked best on your electrodes? Contact us and share your experience.

References

Fritea, L., Bănică, F., Costea, T. O., et al. (2021). Metal nanoparticles and carbon-based nanomaterials for improved performances of electrochemical (bio)sensors with biomedical applications. Materials, 14(21), 6319. https://doi.org/10.3390/ma14216319

Wu, X., Ma, P., Sun, Y. X., et al. (2021). Application of MXene in electrochemical sensors: A review. Electroanalysis, 33(8), 1827–1851. https://doi.org/10.1002/elan.202100192

Coroş, M., Pruneanu, S. M., Stefan-van Staden, R.-I., et al. (2019). Review—Recent progress in the graphene-based electrochemical sensors and biosensors. Journal of The Electrochemical Society, 167(3), 037528. https://doi.org/10.1149/2.0282003jes

Shahzad, S., Çetinkaya, A., Özkan, S. A., et al. (2026). Recent advances in MXene-molecularly imprinted polymer hybrid nanocomposites for electrochemical detection of pandemic-related biomarkers. Analytical and Bioanalytical Chemistry. https://doi.org/10.1007/s00216-026-06772-z