RuFe Alloy Nanoparticle-Supported Mesoporous Carbon: Efficient Bifunctional Catalyst for Li-O₂ and Zn–Air Batteries

Abstract

The design and fabrication of bifunctional catalysts with low cost and high efficiency is a great challenge for the practical application of Li-O 2 batteries. This work presents a bifunctional electrocatalyst consisting of RuFe nanoparticles embedded in high-surface-area nitrogen-doped mesoporous carbon (RuFe@NC). The RuFe@NC-900 catalyst exhibits a specific surface area (677 m 2 g −1 ), pore diameter (9.52 nm), and high pore volume (0.3 cm 3 g −1 ). The catalyst displays high oxygen reduction and evolution reaction activity and exhibited excellent bifunctional activity (ΔE) of 0.73 V vs RHE compared to the benchmark catalyst, 40 wt % Pt/C + RuO 2 substantiates the excellent catalytic activity as an oxygen electrode. The excellent bifunctional activity is attributed to the synergistic effect arising from RuFe@NC type sites, and the high electrical conductivity of the support material was key to tuning the catalytic activity. The potential practical application is further demonstrated by using it as an air cathode for rechargeable metal−air batteries. The Li-O 2 battery constructed with the optimized RuFe@NC-900(5h) cathode exhibited robust reversibility with negligible discharge voltage loss. As a result, the discharge-specific capacity of 11,129 mAh g −1 at a current density of 100 mA g −1 shows a practical approach to explore the high-rate capability by constructing optimal cathode electrodes. In addition, the rechargeable zinc−air battery with RuFe@NC-900(5h) as a bifunctional catalyst exhibits high activity and stability during battery discharge, charge, and cycling processes. Therefore, RuFe@NC can be a potential air cathode for non−aqueous and aqueous rechargeable metal−air batteries.

Recent Advances in Engineered Ru‐Based Electrocatalysts for the Hydrogen/Oxygen Conversion Reactions

“…The as‐prepared RuFe alloy nanoparticles embedded nitrogen‐doped porous carbon (RuFe@NC‐900) has exhibited excellent alkaline ORR catalytic activity by achieving E 1/2 at 0.85 V vs RHE and excellent performance in Li‐O 2 (the discharge specific capacity is 11129 mAh g –1 ) and Zn–air batteries (the discharge specific capacity is 751 mAh g Zn –1 ). [ 152 ] Furthermore, Ru as dopants in Ru‐doped Ru‐Pt 3 Co octahedral alloy nanoparticles (Ru‐Pt 3 Co/C) can effectively inhibit the dissolution of Co and suppress the excessive reduction of Pt during ORR process, which highly boost the catalytic activity and stability. DFT calculations showed that the introduction of Ru further improves the charge distribution of Ru‐Pt 3 Co/C, which not only accelerates the dissociation of O 2 but also promotes the desorption of the *OOH intermediate, achieving superior mass activity of 7.5 times compared to that of commercial Pt/C.…”

Simultaneous optimization of CoIr alloy nanoparticles and 2D graphitic-N doped carbon support in CoIr@CN by Ir doping for enhanced oxygen and hydrogen evolution reactions

“…All these conrm that the conductivity inuenced by N type in the support can greatly enhance the catalytic performance owing to better charge transfer capacity, especially the higher graphitic N content. To estimate the relative activity of electrocatalysts, ECSA was evaluated by the C dl measurement from CV curves at different scan rates (10,20,40,60,80, 100 and 120 mV s À1 ) (Fig. S9 †).…”

“…The catalyst support has been reported to signicantly improve the dispersion and stability of metal nanoparticles, which act as catalytically active sites. [18][19][20][21][22] Moreover, the chemical bonding between metal nanoparticles and support interface will probably induce the strong metal-support interaction (SMSI) effect to efficiently optimize the electron transfer and local electronic structures of active metal particles, which can further modulate the adsorption energies of reaction intermediates for enhanced catalytic activity. 19,23 Usually, nitrogendoped carbon materials with high surface area, excellent conductivity and easy accessibility can work as a representative support to stabilize metal nanoparticles.…”

“…19,23 Usually, nitrogendoped carbon materials with high surface area, excellent conductivity and easy accessibility can work as a representative support to stabilize metal nanoparticles. 20,24,25 More than that, the N dopants, especially the graphitic-N and pyridine-N in the carbon lattice also regulate the electronic distribution of the carbon-based network due to higher electronegativity of N atoms, which can improve its performance and stability by enhancing p bonds. [26][27][28][29] Based on the active N-doped carbon support, strong metal-support interaction and intrinsic activity of the support can protect metal nanoparticles from acid/ alkaline corrosion and agglomeration during the catalytic process, which can improve the utilization efficiency and catalytic performance of catalysts.…”

MOF-derived CoFe alloy nanoparticles encapsulated within N,O Co-doped multilayer graphitized shells as an efficient bifunctional catalyst for zinc--air batteries

“…For example, highly efficient RuFe@NC catalysts have been reported by alloying noble and transition metals, which could alter their intrinsic activity by inducing lattice strain in the alloy. 35 Unfortunately, the reliance on precious metals has not been avoided. Ma et al 36 reported the bifunctional N-GCNT/ FeCo catalyst that exhibits a positive half-wave potential of 0.92 V. However, the sample requires a multi-step carbonization process.…”