Yang Yusheng,Zhang Shuyan,Wang Tuoyao,Zhao Ran,Zhao Zengwu
Energy storage devices and conversion systems have attracted more and more attention with the rapid development of clean energy. Iron oxide is widely used as electrode materials and electrocatalysts because of its abundant resource, low cost, and superior electrical and catalytic properties. Doping sulfur in iron oxide is an effective method to improve electrochemical and photocatalytic performance. The common synthesis method of sulfur-doped iron oxide is a three-step method of co-precipitation, hydrothermal, and calcination. This method has to be performed under high pressure and high temperature, so it needs to consume more energy. In this work, the electrochemical synthesis of sulfur-doped iron oxide was investigated under atmospheric pressure and temperature in the aqueous ferrous sulfate solution that was used as the precursors of sulfur, iron and oxygen. The influences of solution pH on the electrochemical synthesis process and the composition and morphology of deposits were investigated by the analyses of electrochemical reaction and SEM–EDS of deposits. It was found that the oxygen content in the deposit decreased as the pH value of the solution increased. There were three electrochemical reduction processes in sequence from positive to negative potential, followed by the underpotential deposition of iron on the platinum electrode, hydrogen evolution and sulfur doping. The sheet sulfur-doped iron oxide was successfully prepared by electrodeposition under a potential more negative than −1.70 V vs MSE. The kinetics of the electrochemical reaction of iron ions on the platinum electrode was investigated. The reduction process was a quasi-reversible process controlled by diffusion. The heterogeneous charge transfer rate constant k s and the diffusion coefficient D were obtained.
Kangkang Wang,MengQian Wang,Weiwei Lv,Jiming Yao,Wei Zhang,Xiaoyan Li
Purpose An indirect electrochemical reduction and dyeing with indigo were carried out here to solve problems of low dye reduction rate and poor dyeing depth in the current electrochemical dyeing process. Design/methodology/approach Response surface analysis tests were performed to evaluate the effects of ferrous sulfate concentration, medium concentration, sodium hydroxide concentration and reduction time on the reduction efficiency of indirect electrochemical reduction of indigo. Findings The conditions obtained by design-expert optimization showed that the concentration of FeSO 4 ·7H 2 O has the most significant effect on the reduction performance of dye liquor. Under the optimized electrochemical reduction dyeing process, the rate of dye reduction could be reached 91.21 per cent and the K/S value of indirect electrochemical dyeing of indigo can be achieved to 12.96, which is increased by about 9.56 per cent compared with that of Na 2 S 2 O 4 dyeing with the same color fastness basically. Research limitations/implications The recyclability and biodegradability of the dye remain to be explored. Practical implications The strategy presented here can be developed to replace a substantial part of electrochemical dyeing with optimized product quality and reduced environmental pollution in denim production. Social implications The strategy presented here can be developed to replace a substantial part of electrochemical dyeing with optimized product quality and reduced environmental pollution in denim production. Originality/value Application of the Fe(II)-DGS-Abal B complex media system in the indirect electrochemical reduction of indigo.
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