Carbon-Layer-Protected CoP/Carbon Nanosheets as Highly Durable Bifunctional Electrocatalysts for Rechargeable Zinc–Air Batteries

Abstract

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.

Recent Developments of Carbon Dots for Advanced Zinc‐Based Batteries: A Review

“…voltage than the equivalent with the commercialized catalyst (Figure 20d). [102] Analogous to transition metal-based electrocatalysts, layered double hydroxide (LDH) are also perceived as promising catalysts in improving the OER by reason of their large specific surface area, unique 2D lamellar structures, and adjustable chemical properties, whereas the finite numbers of active sites with an inferior catalytic activity in LDH hamper their electrocatalytic ORR activity. [103][104][105] According to the investigations by predecessors, preparing ultrathin LDH nanosheets and LDH integrated CDs are regarded as advantageous methods to improve the electrocatalytic OER activity through exposing more active sites and modulating the surface electronic structure.…”

Constructing Chainmail-Structured CoP/C Nanospheres as Highly Active Anodic Electrocatalysts for Oxygen Evolution Reaction

“…16 Therefore, the strategy of using carbon materials to modify the CoP is an effective method to improve the OER performance of the CoP. 17 For instance, Wu et al reported a series of carbon-coated cobalt-based materials. Among them, carbon-encapsulated CoP nanowires (CoP/C NWs) exhibited an outperform OER performance, whose overpotential for OER is just 230 mV.…”

“…Transition metal phosphides (TMPs), especially cobalt-based phosphides (CoP), have shown great potential as OER catalysts due to their large earth abundance, outstanding electrical conductivity, and excellent catalytic stability. , However, further practical application of CoP is significantly hindered because of its large overpotential and deficient active sites. , On account of the powerful synergistic effect between carbon materials and active materials, such as (CoP), these composite materials can increase the surface area of catalysts to obtain abundant active sites and then promote charge transfer . Therefore, the strategy of using carbon materials to modify the CoP is an effective method to improve the OER performance of the CoP . For instance, Wu et al reported a series of carbon-coated cobalt-based materials.…”

Fabrication of Hollow CoP/FeP Nanocatalysts from Metal‐Organic Frameworks for Oxygen Reduction and Evolution Reactions

“…[11] Among them, CoP have garnered significant research attention in this research field, owing to its metalloid characteristic property and remarkable electronic conductivity. [12] To optimize the morphology and composition of nanocatalysts, Wu et al fabricated a composite electrocatalyst consisting of highly dispersed Co/CoP heterojunction embedded within a hierarchically porous carbon matrix, which exhibited exceptional performance for hydrogen and oxygen evolution. [13] Though more and more researchers focused on the preparation of high-activity cobalt-based phosphides in recent years, it is still a challenge to synthesize uniform CoP nanocatalyst with well-defined morphology and long-term durability.…”