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Data Brief. 2017 October; 14: 68–72.
Published online 2017 July 14. doi:  10.1016/j.dib.2017.07.030
PMCID: PMC5526520

Sample preparation and electrochemical data of Co3O4 working electrode for seawater splitting

Abstract

In this data article, we presented the electrochemical data of the working electrode made of Co3O4 semi-transparent film. Electrochemically stable, porous nature of Kirkendall-diffusion grown Co3O4 films were applied to generate hydrogen from the seawater splitting (Patel et al., 2017) [1]. The data presented in this article includes the photograph of prepared samples, polarization curves for water oxidation and Tafel plot, linear sweep voltammetry measurements under the pulsed light condition in 0.1 M Na2S2O3 electrolyte, and transient photoresponses with natural sea water. Moreover, seawater splitting using the Co3O4 working electrode is demonstrated.

Keywords: Co3O4 semitransparent film, Porous Co3O4 working electrode, Kirkendall-diffusion, Sea water splitting

Specifications Table

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Value of the data

  • • Photographs of the Co3O4 samples for the large working area of 60 mm2.
  • • Polarization curves for water oxidation can be useful to design the water splitting research.
  • • Linear sweep voltammetry of Co3O4 working electrode in 0.1 M Na2S2O3 electrolyte examined for photocathode properties
  • • Spectral responses of Co3O4/FTO photocathode with natural seawater at over potential of 0.33 V vs RHE are promising for photo-catalyst water splitting application.

1. Data

Fig. 1 shows the photographs of the developed porous Co3O4 films on the FTO/glass substrate. Co3O4 films were masked using Kapton tape to define the working area (60 mm2) for electrochemical experimentation are shown in Fig. 1b. Polarization curve for water oxidation cycle (as shown in Fig. 2) are presented for the natural sea water. Tafel analysis is presented in Fig. 2b. Linear sweep voltammetry (LSV) measurement of the porous Co3O4 electrode was measured under a pulsed light (100 mW/cm2) condition with 0.1 M Na2S2O3 electrolyte in cathodic direction, as shown in Fig. 3. Fig. 4 shows the spectral photoresponse of Co3O4/FTO photocathode with natural sea water at over potential of 0.3 V vs RHE. Photoinduced seawater splitting using the porous Co3O4 working electrode is demonstrated in the moving clip. In this video current density is 20 mA/cm2 @ −0.8 V vs RHE.

Fig. 1
Photographs of the developed porous Co3O4 films on the FTO/glass substrate. (a) as prepared 150 nm thick Co3O4 layer on the 500 nm thick FTO-coated glass. (b) Co3O4 films were masked using the Kapton tape so that 60 + 0.5 mm2 of the planar ...
Fig. 2
Electrochemical characterization of the Co3O4 electrode for the anodic potential. (a) Current-voltage characteristics and (b) Tafel plot derived from (a).
Fig. 3
LSV measurement of porous Co3O4 electrodes under a pulsed light condition with 0.1 M Na2S2O3 electrolyte.
Fig. 4
Spectral response of Co3O4/FTO photocathode with natural seawater showed fast transient at applied over potential 0.33 V vs RHE.

2. Experimental design, materials and methods

Preparing Co3O4 electrode: Co3O4 working electrodes were prepared using the Kirkendall diffusion method [1]. Initially the sputtered pure Co film was grown for the porous and semitransparent Co3O4 film by the heat treatment (550 °C for 10 minutes in air condition). Photographs of Co3O4 samples are shown in Fig. 1.

Electrolytes:

  • 1.
    Natural seawater: Yellow Sea near the Incheon National University at 37.3751° N, 126.6328° E coordinate (7 Jun 2016, pH 7.69 (Martini Instruments, pH 56), White light source 100 mW/cm2, current density 20 mA/cm2 @ −0.8 V vs RHE
  • 2.
    0.1 M Na2S2O3: Aqueous electrolyte (100 ml) was prepared from the laboratory grade Na2S2O3

Electrochemical Measurements: All measurements were done using the three electrode electrochemical cells (Reference electrode: Ag/AgCl (KCl, 3 M), Counter electrode: platinum gauze, and working electrode: Co3O4/FTO/glass) attached to the Potentiostat/Galvanostat (PG-stat) (WonA Tech, ZIVE SP1). Linear sweep voltammetry was applied to measure the anodic polarization and photocathode properties. Chronoamperometry technique was applied to measure the transient photoresponses at an applied potential of 0.33 V vs RHE in the natural seawater. The white light (5800 K, Bridgelux, ES Star Array, BXRA-56C0700-A) was applied for photoinduced electrochemical measurement. This was calibrated by a power meter (KUSAMMECO, KM-SPM-11). The illuminating light source was calibrated for one-sun light intensity (100 mW/cm2) and was applied in the pulse mode or the continuous mode. For transient photoresponses, a monochromatic light source of wavelength 365 nm (2 mW/cm2), 460 nm (3 mW/cm2), 520 nm (6 mW/cm2), and 620 nm (15 mW/cm2) were applied to working electrode from the front direction.

Acknowledgements

This research was supported by Basic Science Research Program through the National Research Foundation (NRF) of Korea by the Ministry of Education (NRF-2015R1D1A1A01059165), Korea Research Fellowship Program through the NRF by the Ministry of Science, ICT and Future Planning (NRF-2015H1D3A1066311) and Korea Institute of Energy Technology Evaluation and Planning by the Ministry of Knowledge Economy (KETEP-20168520011370)

Footnotes

Transparency documentTransparency document associated with this article can be found in the online version at 10.1016/j.dib.2017.07.030.

Appendix ASupplementary material associated with this article can be found in the online version at 10.1016/j.dib.2017.07.030.

Transparency document. Supplementary material

Transparency document

Appendix A. Supplementary material

Supplementary material

Reference

1. Patel M., Park W.H., Ray A., Kim J., Lee J.H. Photoelectrocatalytic Sea water splitting using Kirkendall diffusion grown functional Co3O4 film. Sol. Energy Mater. Sol. Cells. 2017 (In process (minor revision)

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