WO3 nanostrutures for Photoelectrocatalytic Applications (Dataset)

An electrochemical and photoelectrochemical characterization of WO3 nanostructures has been performed by means of Electrochemical Impedance Spectroscopy and Mott–Schottky measurements, as well as using cyclic voltammetry and Photocurrent density curves. 

Description of methods used for collection/generation of data: 

- Synthesis of Nanostructures

The anodization technique was used for the formation of nanostructures
on the metal surface. Tungsten (99.95%, 0.125 mm thick)
sheets were cut in a circular shape of 1.3 cm2 and then ultrasonically
washed with acetone, ethanol, and deionized water for
2 min. An electrolyte of 1.5 M methanesulfonic, 95% (v/v) water,
and 5% (v/v) [EMIM][BF4] was used. During anodization, 20 V were
applied between tungsten (anode) and platinum (cathode), submerging
both in the electrolyte for 4 h at 50 °C. The hydrodynamic
conditions were modified between 0, 200, 400, and 600 rpm. After anodization, the samples were washed in deionized
water and then calcined at 600 °C for 4 h in air in order to obtain
ordered crystalline structures.

- Electrochemical Characterization

Electrochemical characterization was conducted in a three-electrode
cell with the anodized tungsten film as the anode, platinum as the
cathode, and Ag/AgCl (3 M KCl) as the reference electrode, and an
electrolyte of 0.1 M H2SO4 solution was employed for all the essays.
To analyze the electrochemical properties of samples, electrochemical
impedance spectroscopy (EIS) tests were performed at 1
VAg/AgCl scanning frequencies from 100 kHz to 0.01 Hz.

The procedure involved performing
cyclic voltammetry within a potential range that excludes
faradaic processes, ensuring that only capacitive charging was measured.
The potential was cycled from OCP ± 0.1 V (based on tests
carried out in a wide range of potentials from the OCP as shown
in Figure S3) for three cycles at scan rates of 0.01, 0.02, 0.05, 0.10,
and 0.20 V s−1. Moreover, to determine the semiconductor character
of the samples and to calculate the number of charge carriers,
Mott–Schottky (MS) plots were obtained at a frequency of 5000 Hz,
scanning the potential from 0.0 to 1.0 VAg/AgCl (WO3).

- Photoelectrochemical H2 Production

The photoelectrochemical analysis was carried out using a solar
simulator equipped with a 300 W Xe lamp and an AM 1.5G filter.
The evaluation of the hydrogen production from the water splitting
using the WO3 nanostructures was carried out with the same
configuration three-electrode cell and an electrolyte of 0.1 M H2SO4
solution. Thus, the samples were subjected to light/dark conditions
(16 s light, 4 s dark), applying a potential from 0 to 1.0 VAg/AgCl at 100
mW cm−2.