Efficient fabrication of bimetallic single-atom catalysts (SACs), holding bi-activity to accelerate both electrochemical oxygen reduction (ORR) and evolution reaction (OER), is highly desired for advanced battery devices. The chemical environment...
The commercialization of rechargeable Zn−air batteries (ZABs) relies heavily on the development of costeffective and highly durable bifunctional electrocatalysts that can promote both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Transition-metal phosphides-based carbon (TMPs/C) composites have recently been acknowledged as highly efficient bifunctional catalysts, yet the successful construction of TMPs/C still remains a formidable challenge. Here, we report a carbon dots (CDs)-assisted approach to efficiently fabricate CoP/C nanocomposites with fine microstructures acting as a highly active and durable bifunctional electrocatalyst for both ORR and OER. The CDs act as a stable platform to adsorb and immobilize Co precursors, obstructing the coalescence of small CoP particles during pyrolysis and eventually ensuring the formation of a fine TMPs/C microstructure, where carbon-encapsulated dense CoP particles are uniformly distributed on carbon nanosheets (CoP@C/CNSs). The ZAB assembled using the CoP@C/CNSs as electrode electrocatalysts expresses excellent performance with a high power density of 180.1 mW cm −2 , a relatively high specific capacity (916 mA h g −1 ), and a long cycling life of over 80 h at 10 mA cm −2 . The catalyst with such a configuration is anticipated to provide a practical solution for the production and storage of clean energy.
The efficiency of the oxygen reduction reaction (ORR)
plays a pivotal
role in determining the performance of electrochemical energy storage
devices, such as rechargeable zinc-air batteries (ZABs). Economical
and active electrocatalytic materials are highly desired to drive
efficient ORRs. Carbon-nanostructure-based catalysts derived from
natural biomass or waste, featuring distinct low cost and sustainability,
have been deemed as a promising candidate to substitute expensive
noble-metal-based catalysts for ORR. In this work, we report a green
and cost-effective strategy to produce nanoporous Fe-NC single-atom
electrocatalysts (SACs) for efficient ORRs, using both iron-containing
industrial spent acid (SA) residue and the natural biomass of the
lotus seedpod (LS) as the main raw materials. The SA features two
unique advantages for the SAC synthesis: the Fe3+ acts
as a Lewis acid “scissor” to generate rich nanopores,
and the HCl can remove aggregates to purify the catalyst. The synthesized
Fe-NC SAC shows an improved electrocatalytic activity of the ORR with
a high half-wave potential up to 0.866 V versus RHE, as compared to
the standard 20% Pt/C one, assigned to its favorable surface area,
hierarchically nanoporous structure, and accessible single atomic
active sites. The ZAB assembled using the Fe-NC SAC exhibited high-power
density (140.2 mW cm–2) and long-term durability.
The study demonstrates a sustainable ambition of reusing industrial
wastes and converting biomass into low-cost and high-value materials
for energy conversion technology.
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