Three-dimensional Ni/Ni3Fe embedded boron-doped carbon nanotubes nanochain frameworks as highly efficient and durable electrocatalyst for oxygen evolution reaction

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Highlights

  • 3D Ni/Ni3Fe/B-CNT nanochain frameworks are prepared by a facile hydrolysis strategy.

  • Ni/Ni3Fe/B-CNT hybrid delivers excellent OER performance and long-term stability.

  • The hybrid requires 265 mV to obtain 10 mA cm−2 and its Tafel slope is 62.9 mVdec−1.

  • Excellent OER activity is due to its unique nanoarchitecture and heteroatom doping.

Abstract

The electrocatalytic water splitting is still seriously hindered by the sluggish reaction kinetics, large overpotential, and high cost of oxygen evolution reaction (OER) electrocatalyst. To address such issues, herein, for the first time, three-dimensional porous Ni/Ni3Fe anchored boron-doped carbon nanotubes nanochain frameworks (Ni/Ni3Fe/B-CNT), constructed by ultrasmall Ni/Ni3Fe nanoparticles embedded in highly conductive B-doped CNT chains, are synthesized via a facile self-assembly hydrolysis method and corresponding growth mechanism is revealed. The low-cost Ni/Ni3Fe/B-CNT hybrid delivers excellent OER performance outperforming that of well-established benchmark electrocatalysts (RuO2): it requires only 265 mV to obtain a large current density of 10 mA cm−2 (mass load ~ 0.28 mg cm−2); it shows a small Tafel slope of 62.9 mV dec−1 and excellent long-term stability even after 40 h. The outstanding OER performance of Ni/Ni3Fe/B-CNT is mainly attributed to its unique porous nanoarchitecture with abundant active sites and the synergistic effect between the ultrathin Ni/Ni3Fe nanoparticles and highly conductive B-doped CNT skeleton; these merits facilitate the electron/ion transfer and oxygen bubble release thus significantly improve its OER activity. This work presents a well-designed nanoarchitecture design and facile fabrication strategy to obtain nonprecious transition metal-based OER electrocatalysts with excellent efficiency and long-term stability.

Introduction

It is of great significance to produce environment-friendly and green-sustainable energy resources by the electrolytic and photo-assisted splitting of water. Especially, electron-driven oxygen evolution reaction (OER) has been motivated as a hot research topic among the researchers to obtain ultra-clean energy carrier, which is another way to battle against the depletion of fossil fuel and generous anxieties on greenhouse emission, towards the crave for a clean living environment [[1], [2], [3]]. So far, many earth-abundant transition metals supported electrocatalysts are being reported as an analogue/replace the benchmark oxygen evolution electrocatalysts (Pt/C, RuO2 and IrO2) for the accessible water oxidation electrocatalysis due to the cost and limited resources of those noble electrocatalysts, which absolutely promotes their widespread applications [[4], [5], [6]]. Unfortunately, most of the water-alkali OER electrocatalysts are still far from an application and suffer from efficiency due to the sluggish electron transfer kinetics. Therefore, it requires the speedy construction of alternative highly efficient earth-abundant electrocatalysts that should lower the overpotential/Tafel of water oxidation.

In this regard, keen attention has been dedicated to constructing earth-abundant alternative electrocatalysts for viable and economical water oxidation systems. 3D block transition-metal-based electrocatalysts, such as oxides [7], alloys [8], phosphides [9], carbides [10], selenides [11], borates [12], hydroxides [13], and nitrides [14] are fabricated via several facile strategies for high-performance water splitting electrocatalysis [15,16]. Moreover, sluggish four-electron-transfer kinetics, surface fouling, and aggregation of electro-active sites are the key determinants for the understanding of electrolytic water splitting applications, thus resulting in lack of efficiency [17,18]. On the other hand, most recent fundamental scientific and technological research interests suggest that the encapsulation of electro-active sites in heteroatom doped carbon-based hybrid materials is an extensive route to access the innovative materials with unique properties [[19], [20], [21], [22], [23]]. Moreover, it is necessary to have a general method to construct nanoarchitecture with controlled size, porosity with desired structural and chemical composition.

Recently, nickel and iron-based materials have been discovered as potentially desirable electrocatalysts due to their adsorptive properties, flexible-redox properties, and surface defects [[24], [25], [26]]. In particular, Ni3Fe and its composite materials have considerable attention within the researchers, owing to their exceptional electron/ion transport environments due to its typical redox properties, ultra-high surface areas, synergetic effect and unique electronic structure [27,28]. Previously, Ni3Fe and Ni3Fe supported materials have been concluded as a commendable oxygen evolution catalyst with ~300–400 mV overpotential [[29], [30], [31], [32], [33]]. In this sense, we intended to explore and boost the oxygen evolution behaviours of Ni/Ni3Fe materials by encapsulating in the boron-doped conductive carbon framework (CNT). In this work, for the first time, we present a novel construction of robust electrocatalyst based on Ni/Ni3Fe embedded boron-doped carbon nanotubes (Ni/Ni3Fe/B-CNT) nanoarchitecture, via self-assembly amine/borohydride hydrolysis driven approach of Ni/Fe/C precursor followed by in-situ reduction reaction for sustainable electro-oxidation of water (oxygen evolution) in alkali medium. Moreover, rationally designed Ni/Ni3Fe/B-CNT electrocatalyst overcomes sluggish kinetic barriers by attaining the high surface areas, abundant active sites, less aggregated porous nanoarchitecture, and thus facilitates the ion/electron transfer and bubble release. In addition, B-doped CNT with high flexibility contributes barrier free-electron transports to Ni/Ni3Fe active sites and keep high structure stability during electrolysis.

Section snippets

Materials

Cobalt nitrate hexahydrate (Co(NO3)3).6H2O), carbon nanotube paste (6% CNT), ferric nitrate nonahydrate (Fe(NO3)3).9H2O), sodium borohydride (NaBH4), ethylene glycol (EG), were purchased from Aladdin, Ltd., sodium hydroxide (NaOH), triethylamine (0.729 g mL−1, C6H15N, 99%, TEA), and ethanol were purchased from KESHI, KL., Nafion and platy-like ruthenium oxide nanostructure (RuO2 electrocatalyst, 99.9%) were procured from shanghai Macklin Ltd. All the chemicals were used as received; double

Formation of 3D porous Ni/Ni3Fe/B-CNT nanoarchitecture

It is quite challenging to construct highly-efficient earth-abundant electrocatalysts for OER water splitting due to their sluggish kinetics. To address such issue, based on our detailed results as shown in Fig. 2, Fig. 3, Fig. 4, Fig. 5 and other research literature reviews [34,35], a plausible reaction mechanism is proposed for the construction of Ni/Ni3Fe/B-CNT nanoarchitectures as demonstrated in Fig. 1. In general, the construction of composites or hybrid materials comprise multistage

Conclusions

In this work, to construct the thermodynamically and kinetically stable Ni/Ni3Fe homogeneously encapsulated flexible, inexpensive B-CNT nanosheets as a robust water-alkali electrocatalyst, a facile self-assembly amine hydrolysis driven approach was followed. This obtained result paves path to ease of fabrication of potentially desirable high-performance Ni/Ni3Fe/B-CNT with 265 mV overpotential with a less Tafel slope of 62.9 mV dec1, only composed of earth-abundant non-precious elements, as an

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The research was supported by the National Natural Science Foundation of China (Grant No's. 21773024, 51372033).

References (47)

  • S. Wang et al.

    Nanocoral-like composite of nickel selenide nanoparticles anchored on two-dimensional multi-layered graphitic carbon nitride: a highly efficient electrocatalyst for oxygen evolution reaction

    Appl. Catal. B Environ.

    (2019)
  • X. Hu et al.

    Three-dimensional graphene-supported Ni3Fe/Co9S8 composites: rational design and active for oxygen reversible electrocatalysis

    ACS Appl. Mater. Interfaces

    (2019)
  • S. Jiang Yang et al.

    Boron-doped carbon nanotubes as metal-free electrocatalysts for the oxygen reduction reaction

    Angew. Chem.

    (2011)
  • J. Park et al.

    Iridium-based multimetallic nanoframe@nanoframe structure: an efficient and robust electrocatalyst toward oxygen evolution reaction

    ACS Nano

    (2017)
  • J. Yu et al.

    Ru-Ru2PΦNPC and NPC@RuO2 synthesized via environment-friendly and solid-phase phosphating process by saccharomycetes as N/P sources and carbon template for overall water splitting in acid electrolyte

    Adv. Funct. Mater.

    (2019)
  • L. Zeng et al.

    General approach of in situ etching and doping to synthesize a nickel-doped MxOy (M = Co, Mn, Fe) nanosheets array on nickel foam as large-sized electrodes for overall water splitting

    ACS Appl. Energy Mater.

    (2018)
  • X. Zhang et al.

    FeNi nanoparticles embedded porous nitrogen-doped nanocarbon as efficient electrocatalyst for oxygen evolution reaction

    Electrochim. Acta

    (2019)
  • D. Yang et al.

    Scalable synthesis of bimetallic phosphide decorated in carbon nanotube network as multifunctional electrocatalyst for water splitting

    ACS Sustain. Chem. Eng.

    (2019)
  • Y. Hu et al.

    Scalable synthesis of heterogeneous W-W2C nanoparticle-embedded CNT networks for boosted hydrogen evolution reaction in both acidic and alkaline media

    ACS Sustain. Chem. Eng.

    (2019)
  • B. Zheng et al.

    3D-hierarchical MoSe2 nanoarchitecture as a highly efficient electrocatalyst for hydrogen evolution

    2D Mater.

    (2017)
  • Y. Hu et al.

    W2C nanodot-decorated CNT networks as a highly efficient and stable electrocatalyst for hydrogen evolution in acidic and alkaline media

    Nanoscale

    (2019)
  • B. Yu et al.

    Mo2C nanodots anchored on N‐doped porous CNT microspheres as electrode for efficient Li-ion storage

    Small Methods

    (2019)
  • B. Wang et al.

    Heterogeneous CoFe-Co8FeS8 nanoparticles embedded in CNT networks as highly efficient and stable electrocatalysts for oxygen evolution reaction

    J. Power Sources

    (2019)
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