Yolk-like Pt nanoparticles as cathode catalysts for low-Pt-loading proton-exchange membrane fuel cells

Abstract

Currently, how to reduce the Pt loading in proton-exchange membrane fuel cell (PEMFC) is an urgent task for its practical application. Here, we propose a substrate engineering strategy of Pt catalysts to achieve low-Pt-loading PEMFC application, i.e., using the N-doped porous carbon (NC) with ultrahigh specific surface area (SSA) to trap Pt nanoparticle (NP). The egg-yolk-like Pt NP catalysts (Ptey/NC) have been synthesized successfully by using the strategy. The Ptey/NC not only possesses an ultrahigh SSA of 2271 m2/g and a relatively low-Pt content of 5.48 wt% but also shows better ORR activity and stability in acidic media than commercial 20% Pt/C. Using Ptey/NC as a cathode catalyst, the assembled PEMFC shows a high peak power density. At the ultralow-Ptey/NC loading of 0.03 mgPt/cm2, the Ptey/NC exhibits extremely high mass activity of 1.63 A/mgPt and 1.1 A/mgPt under 250 kPa and 150 kPa back pressure at 0.9 ViR-free in H2/O2 PEMFC, which are mainly attributed to the ultrahigh SSA plus low-Pt-content, rich mesopore structure, fully exposure of Pt (111), and the yolk-like special structure. DFT results further reveal that the interface effect between Pt NPs and NC significantly reduces the adsorption energy of oxygen species and, therefore, boosts its catalytic activity. This work provides a useful solution of using ultrahigh SSA catalyst plus low-Pt content to solve the low-Pt-loading problem, which would speed up the development of low-Pt-loading PEMFCs.