Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum

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.

Carbon‐Based Substrates for Highly Dispersed Nanoparticle and Even Single‐Atom Electrocatalysts

“…Computations reveal that the enhanced ORR activity by B 4 C support was attributed to the synergistic effect between B 4 C and Pd, in which the electrons of Pd transfer to B 4 C, contributing to stronger oxygen adsorption of Pd and major effect on the transformation of O* to OH − . Jackson group prepared boron carbide supported platinum (Pt/B 4 C), which could achieve 50–100% increase in ORR activity in acidic conditions and significantly enhanced cycling stability compared with commercial Pt/C. To elucidate the improved ORR activity, X‐ray photoelectron and absorption spectroscopy technique was used and disclosed the charge transfer across Pt‐B 4 C interface due to the strong metal–substrate interaction.…”

“…As a newly emerging supporting substrate, boron carbide (B 4 C) has gradually attracted intensive interest due to the unique electronic structure, high chemical inertness, and electrochemical stability . B 4 C can serve as a supporting substrate of noble metals, offering enhanced catalytic activity due to metal–substrate synergistic effects.…”

“…Recently, supporting materials have attracted much attention and are extensively studied as efficient electrocatalysts. There are several characteristics essential to function as an excellent catalyst support, namely high surface area to disperse the catalysts, excellent electronic conductivity and chemical stability . By introducing a conductive catalyst support, the size of the catalysts could be effectively tuned, and the electronic conductivity could be greatly enhanced, which could expose more active sites and accelerate the electrocatalytic processes.…”

Electronic metal-support interactions in vacuum vs. electrolyte

“…lectronic metal-support interactions (EMSI) [1][2][3][4][5] describe the electron transfer between metal catalyst nanoparticles and their supporting material due to electronic equilibration. Recently, Kramer and co-workers 6 reported the experimental observation of an inversion of the relative sign of EMSI-related charge transfer in an electrochemical environment compared to vacuum, which they explained with a well-known relation between work function (The work function of a material surface is the minimum energy required to extract an electron therefrom.) and potential of zero charge (PZC) (The PZC is the potential of a metal electrode where it carries zero surface charge-for greater potentials, the metal surface carries a positive charge, and vice versa.)…”

An All Solid‐State Zinc−Air Battery with a Corrosion‐Resistant Air Electrode

“…ORR data demonstrates that the activity of functionalized TiN-TAFePc is better than free TAFePc suggesting a sort of cocatalytic effect from TiN, possibly by metal support interaction, [47,48] Figure S2, (Supporting Information). On bare TiN, ORR required higher overpotential compared to the molecular electrocatalyst and functionalized TiN, Figure S2, (Supporting Information).…”