Faceted nanostructured tellurium for non-enzymatic hydrogen peroxide sensing: Experimental and theoretical investigation

Abstract

A new enzyme-free sensor has been designed on a copper substrate, utilizing faceted nanostructured tellurium (NSTe) to achieve highly selective and sensitive detection of hydrogen peroxide (H₂O₂). NSTe was effectively electrodeposited onto a copper substrate (0.36 cm²) from an aqueous electrolyte at ambient conditions. Growth kinetics and morphological changes at the underpotential deposition (UPD) region were analyzed using high-resolution field-emission scanning electron microscopy (FESEM). The phase purity of NSTe was analyzed using X-ray diffraction (XRD). The reactivity of prominent planes (102,111) obtained from XRD was compared theoretically. Elemental composition, along with the chemical state of the material, was identified from X-ray photoelectron spectroscopy (XPS). The electrocatalytic performance was studied using cyclic voltammetry (CV) and chronoamperometry (CA) in the phosphate buffer saline (PBS) of pH 7 to explore the non-enzymatic sensing properties of H₂O₂ by the NSTe thin film. A distinct reduction peak for H₂O₂ is observed when it interacts with the NSTe catalyst. Acting as a conductive bridge, NSTe enables direct electron transfer between the modified electron and the substrate, eliminating the need for an external mediator. The NSTe film, deposited at −0.013, −0.015, and − 0.02 V, exhibits sensitivity of 1177.14 ± 0.06, 1791.43 ± 0.11, and 1030.00 ± 0.04 μA mM⁻¹ cm⁻² towards H₂O₂, respectively. The highly sensitive electrode exhibits a wide linear detection range of 1.25 μM to 5 mM for H₂O₂, with a correlation coefficient of 0.978 and a response time of less than 6 s. The adsorption behavior and subsequent decomposition of H₂O₂ to water and oxygen were examined using theoretical methods. The developed sensor possesses good selectivity, stability, and reproducibility, which makes it useful for practical applications.