Abstract
Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50–100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure. This shows that purely electronic metal-support interactions can significantly improve oxygen reduction activity without inducing shape, alloying or strain effects and without compromising stability. Optimizing the electronic interaction between the catalyst and support is, therefore, a promising approach for advanced electrocatalysts where optimizing the catalytic nanoparticles themselves is constrained by other concerns.
Highlights
Catalysing the reduction of oxygen in acidic media is a standing challenge
Significant efforts have successfully focused on improving oxygen reduction reaction (ORR) activity by d-band centre engineering via nanoparticulate Pt alloys supported on high-surface area carbon[2,6,7,8]
Transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) analysis confirm similar particle size, shape and packing of the clustered nanoparticles on both supports, while X-ray photoelectron spectroscopy (XPS) and X-ray adsorption near edge structure (XANES) analysis show differences in electronic properties due to metal-support interactions. These differences in electronic properties are correlated with enhanced ORR activity: the surface and mass specific oxygen reduction activity of Pt nanoparticles supported on B4C composites (BC) under rotating disc electrode (RDE) conditions increases by roughly 40% relative to commercial Pt/C, while the kinetic current at 0.9 V shows a 50–100% improvement
Summary
Catalysing the reduction of oxygen in acidic media is a standing challenge. activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern.
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