[emim]OTf离子液体中镀铌不锈钢双极板在PEMFC环境中的电化学行为

Electrochemical Behavior of Stainless Steel with Niobium Electrodeposited in [emim]OTf Ionic Liquids in PEMFC Environment

以对水和空气稳定的离子液体1-乙基-3-甲基咪唑三氟甲磺酸盐([emim]OTf)为电解质,在不锈钢双极板表面电沉积铌,并在模拟质子交换膜燃料电池(PEMFC)环境中研究了镀铌改性的双极板的电化学行为。结果表明,铌镀层以孤岛的形式均匀分布在不锈钢表面,其高度在100nm以内。XPS、XRD测试结果表明,镀铌不锈钢表面生成化学惰性良好的NbO、Nb2O5。在模拟阳极环境中,镀铌不锈钢的腐蚀电位比不锈钢的腐蚀电位提高530mV;恒电位-0.1V时电流密度从4.5315μA·cm-2降低到2.7554μA·cm-2;在模拟阴极环境中,镀铌不锈钢的腐蚀电位比不锈钢提高430mV,恒定电位0.6V时电流密度从4.4008μA·cm-2降低到0.0028μA·cm-2。电化学测试结果表明,镀铌不锈钢的电化学极化性能得到改善,反应电阻增大,提高了耐蚀性能。

In order to enhance the corrosion resistance of 304 stainless steel,niobium was electrodeposited on its surface in air-and-water-stable 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate（[emim]OTF） ionic liquids.The electrochemical behaviors of bare and niobium coated 304 stainless steel were evaluated by electrochemical tests in simulated PEMFC environment.The results show that deposited niobium is finely dispersed on the surface of 304 stainless steel as isolated islands and that the height of isolated island is within 100 nm.The result of X-ray photoelectron spectroscopy（XPS） and X-ray diffraction analysis（XRD） manifest that the smooth and strong chemical inertness compound film is obtained on the surface of 304 stainless steel,which is mainly composed of NbO and Nb2O5.The thin composite film acts as barrier and remarkably improves the corrosion resistance of 304 stainless steel in PEMFC environment.