Elsevier

Materials Letters

Volume 264, 1 April 2020, 127311
Materials Letters

Electrically conductive honeycomb structured graphene composites from natural protein fibre waste

https://doi.org/10.1016/j.matlet.2020.127311Get rights and content

Highlights

  • Bulk synthesis of graphene oxide-waste protein fibres composites.

  • Formation of carbonised Ni-doped composite with honeycomb structure.

  • Carbonised Ni-doped composite with higher conductivity than other fibre composites.

Abstract

A large amount of short and waste protein fibres, including silk and wool generated during fibre processing that is not spinnable, eventually ends up in the landfill. Here we are reporting on using these waste materials for fabrication of conductive composite. We prepared Nickel (Ni) doped textile-based conductive composites from silk, and wool waste fibres in powder forms and graphene oxide (GO), for the first time, by bulk synthesis method. The infrared spectroscopy revealed that the silk and wool formed composites with graphene oxide and Ni. The obtained Ni-doped graphene/protein fibres composites after carbonisation showed a honeycomb structure with high surface area and pore volume. The conductivity of the Ni-doped composites was higher than the undoped composites. Considering the surface area, pore volume and conductivity results, there is a huge potential for the fabricated material from biobased to use as an electrode material.

Introduction

Due to the global growth of luxurious textile, protein fibre consumption has increased, resulting in a high amount of post-industrial and post-consumer fibre waste. Among all protein fibres, wool and silk fibres are high in demand because of their luxurious look, comfort and high market value [1]. A large amount of short and waste fibres generated during fibre processing that are not spinnable eventually ends up in the landfill. There are some studies conducted on the use of protein short fibres composites for thermal-mechanical applications [2], [3]. However, there is no report on the fabrication of waste protein fibres composites in their powder form through a bulk synthesis method for electrode material applications. Furthermore, currently, biomaterial-based composites have drawn more interest because of their nontoxicity. Additionally, the majority of the preparation of electrochemical materials and processing routes are not user-friendly and produce a large amount of toxic waste. The present work aimed to utilise silk and wool waste fibres and graphene oxide to fabricate a protein fibre composite material and study its conductivity. Graphene is a promising material in the electronics industry due to its unique one-atom‐thick two‐dimensional (2D) structure, an ability to form composites with high electrical-thermal conductivity and large surface area. Moreover, the presence of oxygen-containing groups on the graphene surface forms strong interactions with the protein fibre materials. Given that Nickel (Ni) doping on the composites will enhance the electrical properties of the materials, we have trialled Ni doping in this work. It has been reported that Ni can act as a catalyst for CNT (Carbon nanotube) or CNF (Carbon nanofiber) growth on the material after subsequent carbonisation [4]. Therefore, this current work also investigates if the Ni doping and carbonisation of the as-prepared protein fibre composites affect their conductive properties.

Section snippets

Experimental procedure

The waste silk/wool powders were fabricated by milling (S1). The nickel doped/un-doped graphene oxide (GO) composites using silk and wool powder were prepared by the bulk synthesising method (S3, S4). The morphology (scanning electron microscopy (SEM), S7), fine structural analysis (Fourier Transform Infrared (FTIR), S9) and the porosity (Brunauer–Emmett–Teller (BET), S10) analysis on the powder samples were performed. The DC electrical resistance of the compressed powders was measured by a

Results and discussion

The physical appearance of the samples was similar (Fig. S8). The ecru colour of the natural wool and silk powder turned to grey colour in Go and Ni-doped composite, and all the carbonised samples appeared black (S8). The SEM images showed graphene layers wrapped around the powders on the silk-GO and wool-GO composites (Fig. 1a,b). The carbonised nickel doped composites (Fig. 1c,d) showed an altered morphology; a porous honeycomb structure compared to the un-doped carbonised (Fig. S7f, g).

Conclusions

This study establishes a new technique through transition metal doping and subsequent carbonisation to transform protein textile waste into a highly conductive-porous material. The nickel doped graphene composites were prepared from the silk and wool waste fibres. The electron microscopic images showed that the carbonisation of the nickel-doped composites provided more porous honeycomb-like morphology. The infrared spectroscopy revealed that the silk and wool formed composites with graphene

CRediT authorship contribution statement

Rechana Remadevi: Conceptualization, Investigation, Writing - original draft. Md Abdullah Al Faruque: Investigation. Jizhen Zhang: Investigation. Maryam Naebe: Supervision, Writing - review & editing, Funding acquisition.

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.

Acknowledgement

The experiments were carried out with the support of the Deakin Advanced Characterization Facility.

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