Sun Chuanfu, Hu Guilin, Cao Lili, Pan Taijun, Guo Chengfeng, Xia Yuzhen
School of Mechanical and Energy Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China.
ACS Omega. 2024 Jun 24;9(27):29797-29804. doi: 10.1021/acsomega.4c03523. eCollection 2024 Jul 9.
Metal foam flow field suffers serious corrosion issues in proton exchange membrane fuel cells due to its large surface area. Ni and Ni/graphene coatings are prepared under constant and gradient current modes, respectively, to improve the corrosion resistance. The effect of the electrodeposition current mode and the deposition mechanism is studied. Compared with Ni coating, Ni/graphene coating brings low corrosion current density and high coating resistance, effectively enhancing the stability of Ni foam in an acidic environment. Different from Ni coating with a single layer, Ni/graphene deposits have core-shell structure, with graphene coated on the surface of Ni nanoparticles. It is shown that graphene deposits cover the Ni particles during the electrodeposition, which protects nickel particles from agglomeration and forms an inert film on the surface of the porous structure. After an 8 h constant potential test, no significant pitting is observed on the surface of Ni/graphene coating, showing excellent anticorrosion performance. As to the effect of the deposition current mode, it is shown that more composite particles deposit on the upper layer under the gradient current mode, which brings denser protective film and fewer surface defects on the surface. Ni/graphene coating electrodeposited under a gradient current mode between 0 and 10 mA·cm exhibits the lowest corrosion current densities. The values at 50 and 80 °C are only 62.9 and 26.0% of those of uncoated Ni foam, respectively.
由于金属泡沫流场具有较大的表面积，在质子交换膜燃料电池中会遭受严重的腐蚀问题。分别在恒流和梯度电流模式下制备了镍和镍/石墨烯涂层，以提高其耐腐蚀性。研究了电沉积电流模式和沉积机理的影响。与镍涂层相比，镍/石墨烯涂层具有较低的腐蚀电流密度和较高的涂层电阻，有效地提高了泡沫镍在酸性环境中的稳定性。与单层镍涂层不同，镍/石墨烯沉积物具有核壳结构，石墨烯包覆在镍纳米颗粒表面。结果表明，在电沉积过程中，石墨烯沉积物覆盖了镍颗粒，保护了镍颗粒不发生团聚，并在多孔结构表面形成了惰性膜。经过8小时的恒电位测试，镍/石墨烯涂层表面未观察到明显的点蚀，表现出优异的防腐性能。关于沉积电流模式的影响，结果表明，在梯度电流模式下，更多的复合颗粒沉积在上层，这使得表面保护膜更致密，表面缺陷更少。在0至10 mA·cm的梯度电流模式下电沉积的镍/石墨烯涂层具有最低的腐蚀电流密度。在50和80℃时，其值分别仅为未涂层泡沫镍的62.9%和26.0%。
