Bio-inspired designing and fabricating hydrophobic functional surface for advanced fuel cell applications: A review

Biomimetic hydrophobic surfaces (HSs) play a vital role in enhancing fuel cell (FC) performance by addressing flooding issues and improving water and gas transport. This leads to better water management, increased catalytic activity, enhanced thermal stability, and greater corrosion resistance of electrodes. This review classifies various biological HSs and introduces wetting models alongside different types of FCs. It places particular emphasis on the role of HSs within key FC components: like reinforcing the corrosion resistance of bipolar plates, improving mass transfer in gas diffusion and catalyst layers, and enhancing the conductivity of exchange membranes. The improvement of the working performance is specifically manifested in the increase in peak power density, limit current density and conversion rate. Additionally, reductions in interfacial contact resistance and corrosion current contribute to enhanced corrosion resistance. In proton exchange membrane fuel cells (PEMFCs), surface coatings have reduced interfacial resistance from 608 to 9.2 mΩ cm2, while adding carbon nanotubes to the GDL increased peak power density from 0.76 to 1.03 W/cm2. This paper summarizes diverse fabrication methods for biomimetic hydrophobic structures, including additive manufacturing, subtractive manufacturing, coating modification, highlighting the latest advancements in their application to fuel cells. The review also delves into the application of advanced manufacturing approaches such as ultra-precision machining and atomic-level fabrication for FC functional surfaces. Furthermore, it explores the emerging role of machine learning in biomimetic surface design and manufacturing, offering new opportunities to boost FC efficiency. Finally, future research directions for functional surfaces in FC applications are discussed.