br Data Fig shows the photographs of the

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 (100mW/cm2) condition with 0.1M 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 0.3V vs RHE. Photoinduced seawater splitting using the porous Co3O4 working electrode is demonstrated in the moving clip. In this video current density is 20mA/cm2 @ −0.8V vs RHE.
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 10minutes in air condition). Photographs of Co3O4 samples are shown in Fig. 1. Electrolytes: Electrochemical Measurements: All measurements were done using the three electrode electrochemical buy Torin1 (Reference electrode: Ag/AgCl (KCl, 3M), 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 0.33V vs RHE in the natural seawater. The white light (5800K, 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 (100mW/cm2) and was applied in the pulse mode or the continuous mode. For transient photoresponses, a monochromatic light source of wavelength 365nm (2mW/cm2), 460nm (3mW/cm2), 520nm (6mW/cm2), and 620nm (15mW/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)
Data Chemical analyses of the prepared SnS thin film based upon XPS analysis are provided in Figs. 1–3. XPS survey spectra including the Sn3d and the S2p spectra confirm the chemical states corresponding to the Sn+2 and S-2 states. The thickness-dependent surface morphology and cross-sectional FESEM images of vertical layers of SnS stacked on Si wafer are shown in Fig. 4. Cross-sectional images of SnS samples demonstrated the length extension of the vertical SnS layer for a wafer-scale application [1]. This vertical SnS could be one of emerging 2D materials, such as HfS2, [2] MoS2, [3] MoSe2 and WSe2, [4] ReS2, [5] and SnS2, [6]. The thickness of multilayers of SnS was estimated by using the FESEM image, as shown in Fig. 5. Refractive index of the grown SnS films was calculated using the reflectance data. Both reflectance and refractive index data of SnS film are shown in Fig. 6. Photoresponse data of SnS/n-Si device and light switching frequency dependent are shown in Fig. 7. The light source of wavelength 850nm was used to acquire Allelic exclusion data.
Experimental design, materials and methods
Acknowledgements The authors acknowledge the financial support of the 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 Incheon National University.