H2O2 sensing enhancement by mutual integration of single walled carbon nanohorns with metal oxide catalysts: The CeO2 case

The importance of sensing hydrogen peroxide (H2O2) is due to its ubiquity, being extensively used in industry and also being a biologically relevant side-product of several enzymatic processes. Electrochemical sensing is one of the most robust and simple methods for sensing H2O2 and the discovery of new electroactive materials, particularly at the nanoscale, represents a very hot topic of research. Here, we prove that upon appropriate integration of oxidized single-walled carbon nanohorns (ox-SWCNHs) into a per se moderate H2O2 sensor such as cerium dioxide (CeO2), the sensitivity toward H2O2 is enhanced by almost two orders of magnitude (from 0.4 to 160 μA cm−2 mM−1), on par with that of state-of-the-art metal or metal oxide-based sensors. The modified electrode is also very stable (82% response after 2 weeks of continuous use) and the results highly reproducible. The developed nanohybrid ox-SWCNHs@CeO2, characterized fully and whose average size is about 70 nm as measured by both TEM and AFM, was also tested in real case studies such as washing liquids and milk and was confirmed to be a robust and highly selective material, being not affected neither by the presence of complex matrices, nor by interferents in several organic substrates. The high recovery confirmed the excellent specificity and flexibility of this new electrocatalytic material.