Controlled Pt nano-morphology on carbon nanotube sheet deposited via sputtering for high-performance proton exchange membrane fuel cell

초록

A cost-effective, mass-producible carbon nanotube sheet (CNT) with cotrolled surface properties was employed as both the microporous layer (MPL) and the catalyst support. Defects were introduced via acid treatment to enhance catalytic activity, creating two distinct structures: surface-limited defective CNT (SDCNT) and partially unzipped defective CNT (UDCNT). Pt was sputtered at an ultra-low loading of 0.04 mgPt cm-2 to form the catalyst layer. SDCNT enabled the formation of small, uniform Pt particles, achieving 89.8 % higher peak power density than that of the MPL support, and exhibited minimal performance loss after accelerated stress testing. In contrast, UDCNT promoted aggregated Pt cluster formation and delivered 16.0 % lower performance than SDCNT despite a 25.8 % larger electrochemically active surface area, due to increased mass transport resistance and ohmic resistance from structural changes. These results demonstrate that tailoring CNT defect types is critical for optimizing PEMFC performance by balancing oxygen reduction reaction activity and resistance characteristics.

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