Controlled growth of wo₃ pyramidal thin film via hot-filament chemical vapor deposition: Electrochemical detection of ethylenediamine

In this work, the structural, optical, morphological, and sensing features of tungsten oxide (WO₃ ) thin film deposited on a silicon substrate via hot-filament chemical vapor deposition (HFCVD) are described. The experimental characterization tools, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-Vis), and Fourier transform infra-red (FTIR) spectroscopies, etc., were used to determine the properties of WO₃ NPys thin films. The grown WO₃ thin film illustrated closely packed porous pyramidal nanostructures (NPys) of improved grain size properties. The diffraction analysis revealed (100) and (200) of WO₃ phases, suggesting the classic monoclinic crystal WO₃ structure. HFCVD grown WO₃ NPys thin film was employed as electro-active electrode for detecting ethylenediamine in 10 mL of 0.1 M phosphate buffer solution (PBS) by varying the ethylenediamine concentrations from 10 µM to 200 µM at room temperature. With a detection of limit (LOD) of ~9.56 µM, and a quick reaction time (10 s), the constructed chemical sensor achieved a high sensitivity of ~161.33 µA µM⁻¹ cm⁻² . The durability test displayed an excellent stability of electrochemical sensor by maintaining over 90% sensitivity after 4 weeks of operation. This work provides a strategy for a facile preparation of WO₃ NPys thin film electrode for sensor applications.