Elsevier

Solid State Ionics

Volume 371, 15 November 2021, 115756
Solid State Ionics

Nanostructure modulation of Co3O4 films by varying anion sources for pseudocapacitor applications

https://doi.org/10.1016/j.ssi.2021.115756Get rights and content

Highlights

  • Controllable fabricated different morphology of Co3O4 thin films by chemical bath deposition.

  • A facile method for preparing functional Co3O4 layer to enhancing electrochemical performance.

  • The Co3O4 layers formed by Co(CH3COO)2·display honeycomb-like mesoporous structure and good pseudocapacitance performance.

Abstract

We controllable designed and synthesized four kinds of three-dimensional (3D) hierarchical nanostructured Co3O4 thin films directly deposited on the nickel foam surface by a facile chemical bath deposition method. The morphologies of the Co3O4 films were regulated by using different anions (SO42−, NO3, Cl, and CH3COO) originated from the precursors. The effect of different anions on the surface morphologies and pseudocapacitance behaviors of Co3O4 films was investigated by multiple electrochemical methods, including cyclic voltammetry (CV), galvanostatic charge-discharge cycles (GCD) and electrochemical impedance spectroscopies (EIS). The results indicated that the anions in the precursor salts greatly affected the morphology and porosity of the Co3O4 thin film, and consequently exhibited the different electrochemical performances in 2.0 M KOH electrolyte. The Co3O4 thin film prepared from cobalt acetate shown excellent electrochemical performance among the four different Co3O4 thin films electrodes, such as a high specific capacitance (743.8 F·g−1) and nice cycling stability (95.8% retention after 1000 charge-discharges at a high current density of 5 A·g−1). Furthermore, this work also provides a facile large-scale fabrication method to prepare secondary nanostructure on pseudocapacitance materials, such as graphene, transition metal oxides, carbon fibers, for enhancing the electrochemical performance of supercapacitor at low operation temperature.

Introduction

Transition metal oxides (TMDs) are of broad attention owing to their advantage electronic and magnetic properties [1,2]. For achieving desired performance, the controlling methods of morphologies and nanostructure have been applied in various research fields [3,4]. Nanostructured materials have been attracted more and more interests for their physical and chemical properties, and widely applied in advanced devices [[5], [6], [7]]. Among them, the preparation and performance research of hierarchical and secondary nanostructure thin films have attracted a lot of attentions in recent years for their high specific surface area, increased the amount of functional materials and formation of heterojunction [8,9]. A lot of research has been devoted to developed of diverse hierarchical or secondary nanostructured TMDs thin films.

The pseudocapacitance of electrode material depends on the interfacial redox reactions and intercalations. High specific surface area and ultra-small size can provide abundant active sites to store charge in the first few nanometers of the surface. A large number of previous works showed that some TMDs composites using Co3O4 as secondary structure presents excellent electrochemical performance [[10], [11], [12], [13]]. For the addition of secondary nanostructure, the electrochemical performance of these composites were enhanced owing to the higher specific surface areas, content of functional materials increased and large number of heterojunctions. Therefore, effectively preparing a secondary nanostructured Co3O4 layer on the surface of electrode materials is an effective method to enhancing electrochemical performance. Cobalt (II, III) oxides (Co3O4) as a typical TMDs were widely applied in various fields for its low cost, environment friendly, nice corrosion stability, high theoretical specific capacitance and the interesting intercalative pseudocapacitance properties [14,15].

Various nanostructured Co3O4 were prepared by different methods [[16], [17], [18], [19], [20], [21], [22], [23]]. Among these various methods [[24], [25], [26], [27], [28], [29]], Chemical bath deposition (CBD) is an advantageous thin films deposition method for preparing metal oxide thin films on different substrates [30,31]. In addition, the preparation of well-aligned heterojunction structure and thin films by using CBD method showed more advantages, such as the low operating temperature and pressure condition. Compared to other methods, CBD method can preserve the original nanostructure of the substrate materials without being destroyed [32].

In this work, CBD was applied to directly prepare different nanostructures of Co3O4 films at low temperature by changing the cobalt sources with different anions (SO42−, NO3, Cl and CH3COO). We mainly studied the electrochemical property of the different Co3O4 functional layer to looking for a best preparation method of Co3O4 function film. The Co3O4 thin films with different hierarchical and porous nanostructures were in situ deposited on the surface of Ni foam. The electrochemical performances of the four different as-prepared materials were characterized and investigated the role of anions on the morphological evaluation and pseudocapacitance performance. Among these four different morphologies of Co3O4 thin films, the one prepared from cobalt acetate (A-Co3O4) showed a honeycomb like mesoporous structure and exhibited the higher special capacitance (743.8 F·g−1) at current density of 1 A·g−1 in the 2 M KOH solution. The method using cobalt acetate derived Co3O4 thin films will be beneficial to the preparation of the secondary structure of Co3O4 to enhancing the electrochemical performance of the pseudocapacitor. This low-temperature chemical solution deposition procedure is not only easy to mass produce, but also provides a convenient method for growing secondary nanostructures on different electrode materials surface.

Section snippets

Chemical reagents

Cobalt nitrate hexahydrate (Co(NO3)2·6H2O), cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O), cobalt chloride hexahydrate (CoCl2·6H2O), cobalt sulfate heptahydrate (CoSO4·7H2O), acetone, alcohol, potassium hydroxide (KOH) and urea (CO(NH2)2) were all analytical grade and purchased from Sinopharm Chemical Reagent Co. Ltd. All these chemical reagents were used as purchased without further purification.

Preparation of modified electrode

The Co3O4 modified electrodes were prepared by using a facile CBD method. In the preparation

Structure and morphology of samples

Fig. 1 schematically displays the structural evolution process and formation mechanism of the various Co3O4 films. In this CBD process, the formation of nanostructured Co3O4 is followed by steps of nucleation, aggregation and coalescence of particles to form the different hierarchical thin film [33]. In this reaction process, urea is used as the hydrolysis controlling agent which continuously decomposes to form OH ion as the temperature increasing. The main reaction process performs that the OH

Conclusions

In summary, four different thin Co3O4 films were prepared by the CBD method varying cobalt compounds with four different anions (SO42−, NO3, Cl and CH3COO) as the precursors. And these hierarchical and porous thin Co3O4 films were in situ deposited on the surface of Ni foam, which can enhance the pseudocapacitance performance by increasing the active electrochemical materials. The anion groups and substrates have a significant effect on the morphology of Co3O4 thin film prepared. The

Declaration of Competing Interest

The authors declared that they have no conflicts of interest to this work.

We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted.

Acknowledgements

We are grateful to the support from the PhD Start-up Fund of Zhengzhou University of Light Industry (No. 2017BSJJ039).

References (51)

  • E. Lester et al.

    Controlled continuous hydrothermal synthesis of cobalt oxide (Co3O4) nanoparticles

    Prog. Cryst. Growth Charact. Mater.

    (2012)
  • J.M. Xu et al.

    The advances of Co3O4 as gas sensing materials: a review

    J. Alloys Compd.

    (2016)
  • J. Mei et al.

    Cobalt oxide-based nanoarchitectures for electrochemical energy applications

    Prog. Mater. Sci.

    (2019)
  • K.B. Klepper et al.

    Growth of thin films of Co3O4 by atomic layer deposition

    Thin Solid Films

    (2007)
  • R. Perekrestov et al.

    The comparative study of electrical, optical and catalytic properties of Co3O4 thin nanocrystalline films prepared by reactive high-power impulse and radio frequency magnetron sputtering

    Thin Solid Films

    (2019)
  • Y. Zhang et al.

    Well-regulated nickel nanoparticles functional modified ZIF-67 (co) derived Co3O4/CdS p-n heterojunction for efficient photocatalytic hydrogen evolution

    Appl. Surf. Sci.

    (2018)
  • A.H. Hashim et al.

    Electronic, magnetic and structural properties of Co3O4 (100) surface: a DFT+U study

    Appl. Surf. Sci.

    (2018)
  • B.B. Zhang et al.

    Interfaces exchange bias and magnetic properties of ordered CoFe2O4/Co3O4 nanocomposites

    Appl. Surf. Sci.

    (2015)
  • M. Tian et al.

    Layer-by-layer nanocomposites consisting of Co3O4 and reduced graphene (rGO) nanosheets for high selectivity ethanol gas sensors

    Appl. Surf. Sci.

    (2019)
  • Z. Zhao et al.

    Synthesis and electrochemical properties of Co3O4-rGO/CNTs composites towards highly sensitive nitrite detection

    Appl. Surf. Sci.

    (2019)
  • S. Li et al.

    An architecture of dandelion-type Ni-Co3O4 microspheres on carbon nanotube films toward an efficient catalyst for oxygen reduction in zinc-air batteries

    Appl. Surf. Sci.

    (2019)
  • Y. Zhao et al.

    Facile synthesis of interconnected carbon network decorated with Co3O4 nanoparticles for potential supercapacitor applications

    Appl. Surf. Sci.

    (2019)
  • C.R.K. Rao et al.

    Chemical and electrochemical depositions of platinum group metals and their applications

    Coord. Chem. Rev.

    (2005)
  • E. Turan et al.

    Effects of bath temperature and deposition time on Co3O4 thin films produced by chemical bath deposition

    Thin Solid Films

    (2019)
  • C.-W. Kung et al.

    Synthesis of cobalt oxide thin films in the presence of various anions and their application for the detection of acetaminophen

    Sens. Actuat B-Chem.

    (2013)
  • Cited by (0)

    View full text