Bifunctional Single-Atom Cobalt Electrocatalysts with Dense Active Sites Prepared via a Silica Xerogel Strategy for Rechargeable Zinc–Air Batteries

Abstract

The N-doped cobalt-based (Co) bifunctional single atom catalyst (SAC) has emerged as one of the most promising candidates to substitute noble metal-based catalysts for highly efficient bifunctionality. Herein, a facile silica xerogel strategy is elaborately designed to synthesize uniformly dispersed and dense Co-Nx active sites on N-doped highly porous carbon networks (Co-N-C SAC) using economic biomass materials. This strategy promotes the generation of massive mesopores and micropores for substantially improving the formation of Co-Nx moieties and unique network architecture. The Co-N-C SAC electrocatalysts exhibit an excellent bifunctional activity with a potential gap (ΔE) of 0.81 V in alkaline medias, outperforming those of the most highly active bifunctional electrocatalysts. On top of that, Co-N-C SAC also possesses outstanding performance in ZABs with superior power density/specific capacity. This proposed synthetic method will provide a new inspiration for fabricating various high-content SACs for varied applications.

The Scalable Solid-State Synthesis of a Ni5P4/Ni2P–FeNi Alloy Encapsulated into a Hierarchical Porous Carbon Framework for Efficient Oxygen Evolution Reactions

“…Ni 5 P 4 /Ni 2 P–FeNi@C exhibits a lower I D /I G value of 1.14 compared to Ni 5 P 4 /Ni 2 P–Fe–FeNi 3 @AC with a value of 1.36. This difference is due to the formation of NaCl, which improves the carbonization pyrolysis degree of carbonaceous materials [ 23 ]; this aligns well with the XRD results. As a result, Ni 5 P 4 /Ni 2 P–FeNi@C possesses a superior electrical transfer capacity and a graphitic carbon protective layer, contributing to superior catalytic activity and long-term durability.…”

“…Unlike the previous works [ 17 , 18 , 19 , 20 , 21 , 22 ], the sodium-carbonate-assisted pyrolysis strategy can simultaneously induce the in situ generation of a template and pore-former. The process can not only impart a 3D porous nanocrystal-assembled carbon skeleton but also restrain the excessive coalescence of alloy particles and assist in implanting the FeNi alloy into the carbon framework [ 23 ]. After phosphorization treatment, the integrated electrocatalyst comprises a Ni 5 P 4 /Ni 2 P heterojunction and FeNi alloy encapsulated into a carbon shell, dispersedly interspersed into the interconnected carbon framework.…”

Approaches to construct high-performance Mg–air batteries: from mechanism to materials design

“…There are a broad variety of cathode catalysts, such as transition metal oxides, noble metals, and metal macrocyclic compounds. 131–135 This section describes cathode materials that have been used for Mg–air batteries and possible candidate metal–air battery cathodes to guide the design and optimization of Mg–air battery cathodes. Besides, the relationship between the structure of materials and their catalytic electrochemical performance is also reviewed for the purpose of providing a reference for the design of high-performance cathodes.…”

“…Co-based materials are also another important type of cathode catalysts. 132,166,167 The hybrid of Co 3 O 4 and graphene oxide (GO) exhibited surprisingly high activity for the ORR, even far exceeding Pt/C catalysts, even though these two ingredients showed minimal catalytic activity individually. The improvement in ORR efficiency might be ascribed to the optimization of the formation of the electronic structure, stemming from the formation of Co–O bonds on graphene.…”

Hydrogel-Derived Co3ZnC/Co Nanoparticles with Heterojunctions Supported on N-Doped Porous Carbon and Carbon Nanotubes for the Highly Efficient Oxygen Reduction Reaction in Zn–Air Batteries

“…It exhibited a high specific surface area and a large number of mesopores with molecular accessibility, resulting in the desirable four-electron transfer pathway during the ORR. Wang et al 12 obtained atomically dispersed Co−N x active sites on the N-doped porous carbon networks by adopting a silica xerogel route. This catalyst showed outstanding performance in Zn−air batteries with superior power density and specific capacity.…”