Self-Movement of Water Droplet at the Gradient Nanostructure of Cu Fabricated Using Bipolar Electrochemistry

This Article reports on gradient electrodeposition of copper on the surface of a bipolar electrode (BPE). The formation mechanism of the as-fabricated gradient nanostructure is discussed, and the effects of time, potential, and concentration of CuSO₄ solution on the morphology of the deposited structures are investigated. Scanning electron microscopy (SEM) is used to visualize the morphology of the deposited Cu at different positions of the BPE. By scanning from the cathodic pole to the midpoint of the BPE, three distinct structures are observed; (i) nanodendrites, (ii) nanodendrites in the vicinity of nanoparticles, and (iii) nanoparticles. The BPE surface was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. The contact angle measurement of a water droplet reveals a surface with gradient wettability. Modification of the as-electrodeposited Cu surface with 1-dodecanethiol provides self-movement of the water droplet

Combinatorial Investigations of High Temperature CuNb Oxide Phases for Photoelectrochemical Water Splitting

High-throughput combinatorial methods have been useful in identifying new oxide semiconductors with the potential to be applied to solar water splitting. Most of these techniques have been limited to producing and screening oxide phases formed at temperatures below approximately 550 °C. We report the development of a combinatorial approach to discover and optimize high temperature phases for photoelectrochemical water splitting. As a demonstration material, we chose to produce thin films of high temperature CuNb oxide phases by inkjet printing on two different substrates: fluorine-doped tin oxide and crystalline Si, which required different sample pyrolysis procedures. The selection of pyrolysis parameters, such as temperature/time programs, and the use of oxidizing, nonreactive or reducing atmospheres determines the composition of the thin film materials and their photoelectrochemical performance. XPS, XRD, and SEM analyses were used to determine the composition and oxidation states within the copper niobium oxide phases and to then guide the production of target Cu¹⁺Nb⁵⁺-oxide phases. The charge carrier dynamics of the thin films produced by the inkjet printing are compared with pure CuNbO₃ microcrystalline material obtained from inorganic bulk synthesis