Synthesis of novel ZnO nanoparticles with optimized band gap of 1.4 eV for high-sensitivity photo electrochemical detection

Abstract

This present study devoted to systematic synthesis and investigation of zinc oxide (ZnO) nanoparticles with a precisely tailored band gap of 1.4 eV, aiming to their suitability for high-sensitivity photoelectrochemical (PEC) detection. The reaction conditions were optimized in order to get ZnO nanoparticles with narrow band gap and predominantly in the form of 2D nanosheets, exhibiting intriguing properties attributable to their narrow band gap. Structural analysis carried out by using X-ray diffraction (XRD) confirmed the formation of pure ZnO in the wurtzite phase at specific precursor concentrations. It was observed by UV–vis spectroscopy that as the time duration between synthesis of the sample and its annealing was increased from 0, 15, 30–60 days, the band gap reduces from 2.8 to 1.4 eV. Microstructural and morphological analysis by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) elucidated the formation of well-defined 2D nanosheets of ZnO. Further characterization utilizing techniques such as thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and photoluminescence (PL) spectroscopy ensured the formation of pure ZnO phase with absence of impurities and provided insights into the band structure of the synthesized ZnO nanoparticles. Electrochemical properties were evaluated using cyclic voltammetry (CV) and potentio electrochemical impedance spectroscopy (PEIS) techniques in both dark and light conditions, revealing enhanced performance attributed to the optimized band gap. Additionally, the photoelectrochemical detection capabilities of the synthesized ZnO nanoparticles were thoroughly assessed, demonstrating their remarkable sensitivity and stability. This comprehensive investigation highlights the significance of tailoring the band gap of ZnO nanoparticles for advancement in photoelectrochemical detection technologies.