Synergistic Effects of C/α-MoC and Ag for Efficient Oxygen Reduction Reaction

Abstract

It remains challenging to prepare highly active and stable catalysts from earth-abundant elements for the oxygen reduction reaction (ORR). Herein we report a facile method to synthesize cost-effective heterogeneous C/α-MoC/Ag electrocatalysts. Rotating disc electrode (RDE) experiments revealed that the obtained C/α-MoC/Ag exhibited much superior catalytic performance for ORR than that of C/Ag, C/α-MoC, or even the conventional Pt/C. First-principles calculations indicated that the enhanced activity could be attributed to the efficient synergistic effects between Ag and α-MoC/C by which the energy barrier for O dissociation has been substantially reduced. Furthermore, Li-air and Al-air cells were assembled to demonstrate the unprecedented electrochemical performance of C/α-MoC/Ag nanocomposites surpassing the Pt/C. Thus experimental results and theoretical calculations together showed that the heterogeneous C/α-MoC/Ag nanocomposites are a promising alternative to platinum for applications in industrial metal-air batteries.

Silver Nanoparticle/Multiwalled Carbon Nanotube Hybrid as an Efficient Electrocatalyst for the Oxygen Reduction Reaction in Alkaline Medium

“…[20] Similarly, Cao et al also indicated that the catalytic activity of Ag/C was effectively enhanced when α-MoC was deposited onto carbon substrate, and the reason was assigned to the homogeneous distribution of ultrafine Ag NPs facilitated by α-MoC. [21] Interestingly, Cheng et al reported that the electron transfer number could be increased from 3 to 4 accompanied with enhanced catalytic activity, when the loading amount of Ag NPs raised from 20 wt.% to 50 wt.%. [22] Xu et al dramatically increased the loading amounts of Ag from 40 wt.% to 392 wt.%, and the H 2 O 2 yield (corresponding to the 2e À ORR pathway) was observed to decline from 15 % to less than 5 %.…”

“…[17] Jin et al demonstrated that the Ag NPs (2 nm) protected with single-stranded oligonucleotide sequence (ssDNA) exhibited a 3.5e À pathway towards ORR with excellent stability. [21] Interestingly, Cheng et al reported that the electron transfer number could be increased from 3 to 4 accompanied with enhanced catalytic activity, when the loading amount of Ag NPs raised from 20 wt.% to 50 wt.%. [19] Soo et al noticed that the electron transfer number varied from 2 to 4 when nitrogendoped graphene replaced graphene as substrate.…”

Ag/ZrO2/MWCNT Nanocomposite as Non‐Platinum Electrocatalysts for Enhanced Oxygen Reduction Reaction

“…et al synthesized C/α-MoC/Ag ternary heterogeneous electrocatalysts with high ORR performance, and DFT calculations indicated that the introduction of α-MoC can modify the band structure of Ag and enhance the adsorption of oxygen. [27] Recently, some studies have focused on ZrO 2 as ORR catalyst owing to its strong chemical stability and certain ORR activity. [28][29][30] Okamoto investigated the ORR on the surface of ZrO 2 based on first-principles molecular dynamics simulations, it revealed that when H 2 O 2 formed, the bond of H 2 O 2 would spontaneous break and generate OH on ZrO 2 , which efficiently suppressed two-electron pathway and promoted ORR.…”

The behavior of chemical and electrochemical Ag deposition on FeNi‐mesh cathodes in Al‐air battery

“…Because of this property, coupling with other transition metals may also have a synergistic effect . Furthermore, Many studies have shown that changes in the metal contents, as well as the changes in the surface crystal structures, are also an effect on the catalytic activity . Especially in some studies, it is seen that the crystal structure affects the polarization resistance and oxygen reduction affinity …”

“…11,16 Furthermore, Many studies have shown that changes in the metal contents, as well as the changes in the surface crystal structures, are also an effect on the catalytic activity. 15,17 Especially in some studies, it is seen that the crystal structure affects the polarization resistance and oxygen reduction affinity. 18 In this study, FeNi mesh is treated with Ag in two different ways, chemically and electrochemical deposition.…”