Ni-Based Nanoparticle-Embedded N-Doped Carbon Nanohorns Derived from Double Core–Shell CNH@PDA@NiMOFs for Oxygen Electrocatalysis

Abstract

The development of highly efficient electrocatalysts for the oxygen evolution reaction (OER) plays a crucial role in many regenerative electrochemical energy-conversion systems. Herein, we report a novel double core−shell-structured CNH@PDA@NiMOF (CNH−D−NiMOF) composite based on the support of carbon nanohorns (CNHs) and the direction of polydopamine (PDA) on the synthesis of metal−organic frameworks (MOFs). It is found that this unique structure improves the electrocatalytic performance and stability of the composites. Furthermore, a controlled partial pyrolysis strategy was proposed to construct the Ni-based nanoparticleembedded N-doped CNHs. The partial pyrolysis method preserves the framework structure of MOFs for effective substrate diffusion while producing highly active nanoparticles. This leads to the result that the Ni-based nanoparticle-embedded Ndoped CNHs possess higher stability and significantly improved electrocatalytic properties. Among these derivatives, the sample prepared at a pyrolysis temperature of 400 °C (named as CNH−D−NiMOF-400) outperforms most of the reported unprecious-metal catalysts. At current densities of 20 and 100 mA•cm −2 , the overpotentials of CNH−D−NiMOF-400 are 270 and 340 mV for the OER on a carbon fiber paper (CFP), respectively. The outstanding electrocatalytic properties above suggest that this composite is an excellent candidate for the substitution of noble metal-based catalysts for OER.

Carbon Nanohorn-Based Electrocatalysts for Energy Conversion

“…The so-formed hybrid electrocatalyst, pyrolyzed at 400 • C, exhibited excellent stability and good electrocatalytic OER activity, outperforming the commercial noble-metal catalyst and the state-of-the-art Ni-based catalysts [151][152][153][154][155], but also the Ni-based graphene and CNT-based hybrids [156]. [150]. Copyright © American Chemical Society, 2020.…”

“…So far, the best OER activities have been reported for metal oxides such as ruthenium and iridium oxides. In seeking to take distance from these expensive and scarce materials, a double core-shell catalytic system combining N-doped CNHs, MOF, and Ni nanoparticles (N-CNH-Ni-MOF) was prepared by a simple hydrothermal reaction [ 150 ]. Incorporation of CNHs helps to overcome the poor stability of MOFs in high temperatures and polar solvents, while it also improves conductivity.…”

“… Schematic illustrations of the ( a ) synthetic route of N-CNH-Ni-MOF and its derivatives, and ( b ) polymerization of dopamine. Reproduced with permission from [ 150 ]. Copyright © American Chemical Society, 2020.…”

Metal‐organic frameworks‐derived novel nanostructured electrocatalysts for oxygen evolution reaction

“…As another example of modulating the nickel oxide morphology, the core‐shell structure offers a facile mass transport pathway and increased surface area. Guo et al 75 reported core‐shell‐structured CNH@PDA@NiMOF (CNH−D−NiMOF, where CNH is carbon nanohorns and PDA is polydopamine) for an effective OER catalyst. A partial pyrolysis method was initiated to develop the Ni‐based nanoparticle embedded CNH.…”

Fabrication of Core‐Shell Nanocolloids with Various Core Sizes to Promote Light Capture for Green Fuels

“…Core‐shell nanostructures have received intensive interest because of their intriguing physical merits, [1] such as low mass density, large surface area, high permeability, and good mechanical stability. Significantly, the chemical compositions of both core and shell components can be changed and tailored, which may endow the core‐shell materials with high complexity and diversity, thus making them quite promising in various emerging applications, including electrochemical energy storage, [2–6] photocatalysis, [7–12] electrocatalysis, [13,14] biomedical [15,16] and sensing [16–18] . In the past few years, different kinds of inorganic nanomaterials, such as TiO 2 , Al 2 O 3 , CeO 2 , NiS, CdSe, Ag, and Pt have been rationally designed and then fabricated into core‐shell structures to realize specialized functionalities [19] …”