Synthesis and Characterization of Ultrathin WO₃ Nanodisks Utilizing Long-Chain Poly(ethylene glycol)

Abstract

Metal oxide nanostructures hold great potential for photovoltaic (PV), photoelectrochemical (PEC), and photocatalytic applications. Whereas thin films of various materials of both nanoparticle and nanorod morphologies have been widely investigated, there have been few inquiries into nanodisk structures. Here, we report the synthesis of ultrathin WO 3 nanodisks using a wet chemical route with poly(ethylene glycol) (PEG) as a surface modulator. The reported nanodisk structure is based on the interaction of the nonionic 10000 g/mol PEG molecules with tungsten oxoanion precursors. The WO 3 nanostructures formed are dominated by very thin disks with dimensions on the nanometer to micrometer scale. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images reveal the structures to have dimensions on the order of 350-1000 nm in length, 200-750 nm in width, and 7-18 nm in thickness and possessing textured single-crystalline features. A number of analytical techniques were used to characterize the WO 3 nanodisks, including selected-area electron diffraction (SAED), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), Raman scattering spectroscopy, UV-visible spectrophotometry, and cyclic voltammetry (CV). The growth of the WO 3 nanodisks was inhibited in the [010] crystal direction, leading to ultrathin morphologies in the monoclinic crystal phase. The large flat surface area and high aspect ratio of the WO 3 nanodisks are potentially useful in PEC cells for hydrogen production via direct water splitting, as has been demonstrated in a preliminary experiment with external bias.

Synthesis, Separation and Electrical Properties of WO3-xNanopowders via Partial Pressure High Energy Ball-Milling

“…The conductivity further increases and the value of activation energy of WO 2.7 NP is about 0.28(3) eV which corresponds to n-type semiconductor-like behavior. Results of WO 3 NPs conductivities and their interpretations as non-stoichiometric (process A) and hydrate (process B) originates from oxygen vacancies and are compatible with similar works that have been carried out in study of WO 3 thin films as a sensing material for detection of atmosphere pollutants [25][26][27][28][29][30][31].…”

“…The conductivity is calculated from the experimentally determined resistance R, which is monitored during the three heating and cooling cycles. The activation energy of conduction, E A , was frequently interpreted using the Arrhenius equation between 300 and 700 K. Our results are compatible with the principle results of conductivity of WO 3−x thin films [19][20][21][22][23][24][25][26]. It is obtained from the following formula:…”

Photoelectrochemical Study of Nanostructured ZnO Thin Films for Hydrogen Generation from Water Splitting

“…The dimensionality of metal oxides has also been widely investigated for 0D, 1D and 2D nanostructures. [23][24][25][26][27] Colloidal wet chemistry, chemical vapor deposition (CVD) and magnetron sputtering have proven versatile in the creation of metal oxides with nanometersized features. [23,[28][29][30][31] It has been found that the charge transport properties of metal oxide nanoparticles-and nanorod-based PEC cells are superior to those of traditional metal oxide thin film cells.…”

Optical and Dynamic Properties of Undoped and Doped Semiconductor Nanostructures

“…Solar energy conversion into electricity or chemical energy such as hydrogen represents one of the most promising applications of optical properties of nanomaterials [190,[192][193][194][195]231]. For example, dyesensitized solar cells have attracted significant attention since the initial report in 1991 of a power conversion efficiency of 12 % [190].…”