CuOx nanostrutures synthesized under hydrodynamic conditions photoelectrochemical applications (Dataset)

CuOx (x = 1 and 2) nanostructures have been synthesized by electrochemical anodization inethylene glycol based electrolytes using oxalic acid or NaF (with or without NaOH) as complexing agents.The influence of hydrodynamic conditions and time during anodization of copper have also been evaluated.A electrochemical and photoelectrochemical characterization of the nanostructures has been performed. Description of methods used for collection/generation of data: - Synthesis of CuOx nanostructures For the fabrication of the CuOx nanostructures, copper foils(99.9%, 0.125 mm thick) were washed using an ultrasonic bathfor 15 seconds in 0.1 M HCl and 30 seconds in acetone,ethanol, and deionized water, respectively and then dried witha flow of N2.The anodization of copper was performed using a two-electrodeelectrochemical cell with the copper sheet as the working electrode and platinum foil as the counter electrode.The experimental variables were the electrolyte, the anodizationtime and the use of hydrodynamic conditions.All the tests were carried out by connecting the workingelectrode to a rotating disk electrode, RDE, (Fig. 1), with anexposed area of the copper foil to the electrolyte of 1.32 cm2. Copper was first anodized in 70% (v/v) ethylene glycol (EG)and 30% (v/v) deionized water with different complexingagents, both in 0.05 M: oxalic acid and sodium fluoride. Theinfluence of the presence of 0.1 M NaOH in these solutionswas also studied. The samples were anodized in each solution for differenttimes (5, 10 and 15 minutes) at 50 °C and a voltage of 20 V. To evaluate the influence of hydrodynamic conditionsduring anodization, films were anodized by varying the RDErevolutions at 0, 250 and 500 rpm.After anodization, foils were carefully cleaned with ethanoland deionized water before being dried with a N2 stream.Afterwards, samples were annealed in air at 250 °C for 1 h. - Electrochemical and photoelectrochemical characterization These measurements were carried out in a three electrode cell with the anodizedCu film as the anode, platinum as the counter electrodeand Ag/AgCl (3 M KCl) as the reference electrode, using anelectrolyte solution of 0.1 M Na2SO4. Electrochemical impedance spectroscopy (EIS) tests were performed at −0.2 VAg/AgClusing an amplitude of 0.01 V and scanning frequencies from100 kHz to 0.01 Hz. Besides, in order to know the semiconductorcharacter of the nanostructures Mott–Schottky (MS)plots were carried out at a frequency of 5000 Hz, scanning thepotential from 0.1 to −0.5 VAg/AgCl. Photoelectrochemical characterization was conducted by scanning the potential from0 to −0.8 VAg/AgCl alternating dark and illumination conditions(16 s dark, 4 s illumination) with UV light (λ = 365 nm) providedby a LedControl UV LED (Opystec Dr Gröbel Germany) ata power of 100 mW cm−2.