Abstract
Nanoscale Au-ZnO heterostructures were fabricated on 4-in. SiO2/Si wafers by the atomic layer deposition (ALD) technique. Developed Au-ZnO heterostructures after post-deposition annealing at 250 °C were tested for amperometric hydrogen peroxide (H2O2) detection. The surface morphology and nanostructure of Au-ZnO heterostructures were examined by field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), etc. Additionally, the electrochemical behavior of Au-ZnO heterostructures towards H2O2 sensing under various conditions is assessed by chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that ALD-fabricated Au-ZnO heterostructures exhibited one of the highest sensitivities of 0.53 μA μM−1 cm−2, the widest linear H2O2 detection range of 1.0 μM–120 mM, a low limit of detection (LOD) of 0.78 μM, excellent selectivity under the normal operation conditions, and great long-term stability. Utilization of the ALD deposition method opens up a unique opportunity for the improvement of the various capabilities of the devices based on Au-ZnO heterostructures for amperometric detection of different chemicals.Graphical abstract
Highlights
The development of different nanoscale two-dimensional (2D) heterostructures for their usage in various electrochemical devices is modern and established trend during the last decade of the twenty-first century [1–5]
Due to the electro-active nature of H2O2, non-enzymatic electrochemical detection method can be considered as a valuable alternative for selective H2O2 detection [41] considering that it possesses the rapid response with great stability, wide linear detection range, high precision, low cost, and simplicity [2]
The outstanding properties of Au-ZnO heterostructures for enhancing the analytical sensing performance of electrochemical sensors are due to the following: (i) the Schottky contacted between nanostructured Au and ZnO results in generation of the thicker depletion layer at the Au/ZnO interface compared with the bare ZnO nanostructure; (ii) the inert surface nature of ZnO; and (iii) high selectivity of Au co-catalyst for direct 2e− reaction, which maximizes the H2O2 detection
Summary
The development of different nanoscale two-dimensional (2D) heterostructures for their usage in various electrochemical devices is modern and established trend during the last decade of the twenty-first century [1–5]. The outstanding properties of Au-ZnO heterostructures for enhancing the analytical sensing performance of electrochemical sensors are due to the following: (i) the Schottky contacted between nanostructured Au and ZnO results in generation of the thicker depletion layer at the Au/ZnO interface compared with the bare ZnO nanostructure; (ii) the inert surface nature of ZnO; and (iii) high selectivity of Au co-catalyst for direct 2e− reaction, which maximizes the H2O2 detection. Au-semiconductor hetero-interfaces have a critical effect on the properties of the surface layer if the thickness of such a layer is just a few nanometers In this regard, ALD technology is imperative for fabrication of the wafer-scaled semiconductors with nanometer thickness. Nanoscale ZnO has clearly demonstrated unique properties as well as excellent electrochemical capabilities in photovoltaics, catalysts, batteries, and different chemical sensors [47–53]. Despite outstanding reported properties and wide usage of ZnO in many applications, Au-ZnO heterostructures have not yet been reported for electrochemical H2O2 sensing
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