An amphiphilic polyoxometalate–CNT nanohybrid as a highly efficient enzyme-free electrocatalyst for H2O2 sensing

Abstract

Hybrid nanomaterials are emerging as a potential platform for the efficient detection of biomolecules; thus, the rational design of such materials has been widely explored. Polyoxometalate (POM) nanoclusters can serve as advanced multifunctional structures for sensing and catalytic applications owing to their versatile structures and tunable redox properties. Here, in this work, POM amphiphilic building blocks are assembled on the CNT surface via non-covalent interactions using long alkyl chain surfactant molecules and their electrocatalytic performance is investigated for the detection of H₂O₂. It has been revealed that the POM–CNT based modified gold electrode exhibits outstanding electrocatalytic ability for the detection of H₂O₂ with a high selectivity. The synergy between POM nanoclusters and CNTs results in an enhanced reproducible sensitivity of 11 450 µA mM⁻¹ cm⁻² (R² = 0.994) with a low detection limit of ∼0.5 µM. The POM–CNT/Au electrode demonstrates a 10 times higher current response than pristine POM building blocks, a fast response time of <2 s, good stability and long shelf-life. The DFT calculations reveal that CNTs mainly contribute to H₂O₂ sensing by facilitating the reduction of Keggin molecules. Moreover, the amphiphilic structures display good sensitivity towards H₂O₂ detection in the commercially available real samples, suggesting a new path to design and develop POM-based multifunctional materials for electrocatalytic applications.