Application and optimization of carbon supports in proton exchange membrane fuel cells

As the energy crisis and environmental pollution continue to intensify, there is an increasingly urgent need for devices with high energy conversion efficiency and low pollution. Proton exchange membrane fuel cell (PEMFC), as a green energy conversion device with high efficiency and zero pollution, is considered as a promising alternative to traditional energy. At present, making automotive fuel cell systems competitive in the market still faces challenges in terms of cost and durability. The current mainstream way to reduce costs is to reduce the platinum load on the catalyst. However, lower platinum loading usually means a smaller catalyst surface area and greater mass transfer resistance, resulting in loss of performance. In addition, the durability problem is also a major obstacle restricting the development of fuel cell vehicles, especially the problem of carbon corrosion. From the perspective of optimizing carbon supports, this review first combined the current research status in the field of carbon supports, and proposed the characteristics of ideal carbon supports by comparing commercial carbon supports and novel carbon supports. Secondly, based on the theory of oxygen transport resistance, different optimization strategies were discussed from the aspect of optimizing the mass transfer ability of carbon supports, including the construction of ordered column array structure, the regulation of pore structure and the regulation of surface properties of carbon supports. Among them, optimizing the pore structure of carbon supports to enhance the local mass transfer capacity is a commonly employed strategy, and mesoporous carbon supports are a prominent example of this strategy. Ordered column arrays, represented by vertically aligned carbon nanotubes (VACNT), have attracted wide attention due to their high ordered structure, efficient transport path and high catalyst utilization potential. However, they still face difficulties in water management and large-scale manufacturing. In addition to the above two strategies, the uniform distribution of the ionomer film through the surface modification of the carbon supports is also conducive to mass transfer. Then, in terms of carbon corrosion, considering the impact of carbon corrosion on the durability of PEMFC, strategies to improve the corrosion resistance of carbon supports were reviewed according to the reaction and theoretical analysis of carbon corrosion, including improving the degree of graphitization, physical coating, adding OER catalyst, surface treatment and increasing the hydrophobicity of supports. The obvious and direct way to improve the corrosion resistance of carbon supports is to increase the graphitization degree of carbon supports by high temperature calcination to obtain stable carbon structure. Finally, the development direction of carbon supports in the future is prospected, which can provide reference for the construction and design of novel carbon supports. © 2024 Materials China. All rights reserved.