| LI Wan-jing,ZHOU Wan-qiu,XIN Shi-gang,SU Gui-tian,KANG Yan-hong,SUN Qiu-ju.Effect of Cathode Gas Oxygen on Corrosion Resistance of Graphene/Polyaniline/Stainless Steel Bipolar Plates[J],52(5):163-174 |
| Effect of Cathode Gas Oxygen on Corrosion Resistance of Graphene/Polyaniline/Stainless Steel Bipolar Plates |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.05.016 |
| KeyWord:graphene polyaniline stainless steel bipolar plates oxygen ionic liquid corrosion resistance |
| Author | Institution |
| LI Wan-jing |
College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang , China |
| ZHOU Wan-qiu |
College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang , China |
| XIN Shi-gang |
College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang , China |
| SU Gui-tian |
College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang , China |
| KANG Yan-hong |
College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang , China |
| SUN Qiu-ju |
College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang , China |
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| Abstract: |
| Stainless steel is one of the most concerned proton exchange membrane fuel cell (PEMFC) bipolar plate materials with low cost, good machinability and excellent electrical and thermal conductivity. However, it is easy to suffer corrosion in acidic working environment of PEMFC. It is necessary to modify the surface of stainless steel (SS) bipolar plate to improve its corrosion resistance. The results show that the corrosion resistance of polyaniline (PANI) monolayer films synthesized by electrochemistry in aqueous solution system is still inadequate, and the corrosive medium can still penetrate into the metal surface through the polymer film to corrode it. In this paper, polyaniline film was synthesized on the surface of 316L stainless steel bipolar plate in ionic liquid, and then graphene oxide was reduced by electrochemical deposition to form rGO/polyaniline layer-layer composite coating to improve the corrosion resistance of bipolar plate. 316L stainless steel plate of 30 mm×10 mm×1 mm was used as the base, and polished with sandpaper. After cleaning with acetone, pickling and water washing, it was blow-dried for later use. Polyaniline thin films were prepared on 316L stainless steel substrate by cyclic voltammetry (CV). The scanning potential ranged from ‒0.8 V to 2 V, the scanning speed was 0.05 V/s, and the cycle was 10 cycles. Then 0.15 mL GO was dropped onto the surface of PANI, and electrochemical reduction was carried out by cyclic voltammetry. The scanning voltage range was from ‒1.6 V to 0.6 V, the scanning speed was 0.02 V/s, and the cycle was 6 cycles. The rGO/PANI layer by layer composite bipolar plate was obtained. The morphology was observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), the structure of functional groups was determined by infrared spectroscopy (FTIR) and Raman spectroscopy (Raman), the conjugation state was determined by UV-vis spectroscopy (UV-VIS), and the chemical composition and bonding state were determined by X-ray photoelectron spectroscopy (XPS). The corrosion resistance of rGO/PANI/316L SS layer-layer composite bipolar plate was studied under the simulated working environment of PEMFC cathode (Oxygen (O2), +0.6 V, 0.2 mol/L H2SO4 aqueous solution). Oxygen was introduced into the system. Open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and polarization curves were measured to evaluate the corrosion resistance of bipolar plates. In the ionic liquid 1-ethyl-3-methylimidazolium methyl sulfate, PANI film with thickness of 53 μm was obtained by electropolymerization. GO was reduced in 0.03 mol/L K2SO4 solution with pH=4, and rGO film with thickness of 10 μm was obtained on PANI. The rGO film was like a layer of light yarn covering the surface of PANI, and the coral-like shape of PANI under the film could be vaguely seen through the rGO film. PANI had an intermediate oxidation state. The interaction between sp2 hybrid rGO and PANI enhanced the conjugation effect. The continuous dense rGO covering the porous PANI improved the corrosion resistance of the bipolar plate. In the rGO/PANI/316L SS system, the corrosion current densities of O2, O2(DO) and N2 were 2.89×10‒6 A/cm2, 3.84×10‒6 A/cm2 and 8.13×10‒6 A/cm2 respectively. In the PANI/316L SS system, the corrosion current densities of O2, O2(DO) and N2 were 2.30×10‒5 A/cm2, 1.39×10‒5 A/cm2 and 1.25×10‒5 A/cm2 respectively. The corrosion current density of rGO/PANI/316L SS system was one order of magnitude lower than that of PANI/316L SS system, indicating that the corrosion resistance of rGO/PANI composite coating was further improved. The corrosion current density of rGO/PANI/316L SS was the lowest in O2. Oxygen had a significant effect on the corrosion resistance of rGO/PANI/316L SS. Oxygen contributes to the formation of a protective passivation film at the membrane/substrate interface, which improves the corrosion resistance of rGO/PANI/316L SS bipolar plates and has a good development prospect in the future. |
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