Abstract
In this article, we proposed a facile method to electrophoretically deposit a highly conductive and corrosion-resistant graphene layer on metal bipolar plates (BPs) while avoiding the oxidation of the metal substrate during the electrophoretic deposition (EPD). p-Phenylenediamine (PPD) was first grafted onto negatively charged graphene oxide (GO) to obtain modified graphene oxide (MGO) while bearing positive charges. Then, MGO dispersed in ethanol was coated on titanium plates via cathodic EPD under a constant voltage, followed by reducing the deposited MGO with H2 at 400 °C, gaining a titanium plate coated with reduced MGO (RMGO@Ti). Under the simulated environment of proton exchange membrane fuel cells (PEMFCs), RMGO@Ti presents a corrosion current of < 10−6 A·cm−2, approximately two orders of magnitude lower than that of bare titanium. Furthermore, the interfacial contact resistance (ICR) of RMGO@Ti is as low as 4 mΩ·cm2, which is about one-thirtieth that of bare titanium. Therefore, RMGO@Ti appears very promising for use as BP in PEMFCs.
Highlights
Proton exchange membrane fuel cells (PEMFCs) are a clean and highly efficient electrochemical devices that convert chemical energy directly into electrical energy, widely used as mobile, portable, and stationary power sources in a wide field of applications [1,2,3,4,5,6,7,8,9].Bipolar plates (BPs) are a multifunctional component in PEMFCs, connecting single cells in a stack, conducting electric current between them, distributing fuel or oxidant to the electrodes, and separating the fuel and oxidant from the neighboring cells [7,10]
The dried modified graphene oxide (MGO)@Ti sample was heat-treated at 400 ◦ C in H2 atmosphere for 2 h, leaving a titanium plate coated with reduced MGO (RMGO@Ti)
The preparation method was similar to the cathodic electrophoretic deposition (EPD) of MGO described above, except that the coating agent was replaced with graphene oxide (GO) dispersed in aqueous with the GO concentration of 0.5 mg·mL−1, the polarity of titanium and carbon plate reversed, and the coating time reduced to 0.5 h
Summary
Proton exchange membrane fuel cells (PEMFCs) are a clean and highly efficient electrochemical devices that convert chemical energy directly into electrical energy, widely used as mobile, portable, and stationary power sources in a wide field of applications [1,2,3,4,5,6,7,8,9]. The material to make BPs should exhibit high corrosion resistance, excellent electrical and thermal conductivity, and gas impermeability [11]. The most common materials to make metallic BPs are stainless steel, titanium, or aluminum, and the factors that guide the material choice are the corrosionresistant, specific weight, mechanical strength, and cost of the metal. None of these metals have satisfied corrosion-resistant in the harsh environment of PEMFCs. While passivated metal would increase interfacial contact resistance (ICR) and lower the power output, dissolved metal ions can poison the catalyst and hinder proton transport in PEMFCs [27]. MGO (RMGO), with H2 at 400 ◦ C to obtain the desired protective coating
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