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# Schematic of the three-electrode measurement system.

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In this research, we propose a new simple method to fabricate high-density Fe2O3 nanowire arrays for solar water splitting, based on oxidation-assisted stress-induced atomic-diffusion. In the presence of water vapor, surface oxidation was promoted during the heating process. The driving force induced by the stress gradient was enhanced due to the e...

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... measurement was carried out using a three- electrode system, as shown in Fig. 1. The fabricated Fe 2 O 3 nanowire array is used as the photoanode, the cathode is a Pt wire with a diameter of 0.05 mm, and Ag/AgCl is used as the reference electrode. These three electrodes were placed in a 1 mol L À1 NaOH solution. The light source is a quartz halogen ber optic illuminator (Fiber-Lite PL800), the spectrum of the ...
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... did not increase the density of the nanowire array. The cross section of the fabricated sample has also observed by using the FESEM, as shown in Fig. 9. Three layers can be easily observed from the SEM image, which include the nano- wire layer, the oxide layer and the iron layer. The morphology of the nanowires fabricated at 450 C was shown in Fig. 10. The shape of nanowires looks like grass, which indicated that nanowires grew from the top of themselves with the precipita- tion of diffused Fe atoms and their oxidation. The average diameter of the nanowires shown in Fig. 10 is 144 nm, approximately. Fig. 11 shows the XRD patterns of the nanowire arrays obtained for different heating ...
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... nano- wire layer, the oxide layer and the iron layer. The morphology of the nanowires fabricated at 450 C was shown in Fig. 10. The shape of nanowires looks like grass, which indicated that nanowires grew from the top of themselves with the precipita- tion of diffused Fe atoms and their oxidation. The average diameter of the nanowires shown in Fig. 10 is 144 nm, approximately. Fig. 11 shows the XRD patterns of the nanowire arrays obtained for different heating temperatures under the water vapor condition of 0.2 L h À1 and heating time of 90 min. From data obtained from different samples, it can be inferred that when the heating temperature is higher than 450 C, the formed Fe 2 O 3 layer on ...
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... and the iron layer. The morphology of the nanowires fabricated at 450 C was shown in Fig. 10. The shape of nanowires looks like grass, which indicated that nanowires grew from the top of themselves with the precipita- tion of diffused Fe atoms and their oxidation. The average diameter of the nanowires shown in Fig. 10 is 144 nm, approximately. Fig. 11 shows the XRD patterns of the nanowire arrays obtained for different heating temperatures under the water vapor condition of 0.2 L h À1 and heating time of 90 min. From data obtained from different samples, it can be inferred that when the heating temperature is higher than 450 C, the formed Fe 2 O 3 layer on Fe substrate is thicker ...
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... photovoltaic properties of the nanowires have been inves- tigated using a three-electrode system (Fig. 1), and the results are shown in Fig. 12. The Fe 2 O 3 nanowire photoanode fabri- cated at 350 C showed the largest photocurrent density among all the photoanodes, 0.65 mA cm À2 at 1.23 V vs. a reversible hydrogen electrode (RHE). Although the nanowire photoanode fabricated at 450 C has the largest density of nanowires, the photocurrent ...
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... photovoltaic properties of the nanowires have been inves- tigated using a three-electrode system (Fig. 1), and the results are shown in Fig. 12. The Fe 2 O 3 nanowire photoanode fabri- cated at 350 C showed the largest photocurrent density among all the photoanodes, 0.65 mA cm À2 at 1.23 V vs. a reversible hydrogen electrode (RHE). Although the nanowire photoanode fabricated at 450 C has the largest density of nanowires, the photocurrent density is lower at 0.47 mA cm À2 , due ...
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... This value is relative high than that of other pure Fe 2 O 3 photoanodes without any func- tional modication, reported by the literatures, such as the The stability of photocurrent was measured at 1.23 V vs. RHE by a chopped illumination with 10 s on/off for 120 seconds, for a Fe 2 O 3 nanowire array photoanode fabricated at 450 C, as shown in Fig. 14. The photocurrent density is very stable and increased and decreased quickly with on and off the light which shows the good photoresponse properties of the Fe 2 O 3 nano- wire array ...
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... Fe atoms diffuse along the stress gradient to the Fe/ Fe 2 O 3 interface, they cumulate at the interface and then nd the weak spots of Fe 2 O 3 layer and penetrate them to form nanowires accompanying the oxidation of the Fe atoms. Aer the nano- wires are formed, Fe atoms continue to diffuse along the nanowires due to the high driving force (see Fig. 15), which explains the formation of longer nanowires with the increase in the heating time. Under the water vapor condition, greater amounts of iron can be oxidized into Fe 2 O 3 , which could increase the thickness of the Fe 2 O 3 layer on the Fe substrate. Therefore, the tensile stress that the Fe layer suffered from the Fe 2 O 3 layer ...

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