Natural aloe vera derived Pt supported N-doped porous carbon: A highly durable cathode catalyst of PEM fuel cell

https://doi.org/10.1016/j.ijhydene.2020.05.056Get rights and content

Highlights

  • A new mesoporous carbon (AVC) has been derived via natural Aloe Vera plant.

  • N-doping into AVC creates more defects, which is beneficial for anchoring Pt NPs.

  • Pt/N-AVC shows the highest ORR and durability after 30,000 cycles (ΔE1/2 ~5 mV).

  • Existence of mesoporosity hinders the agglomeration Pt NPs and retain the stability.

Abstract

Evolution of highly durable electrocatalyst for oxygen reduction reaction (ORR) is the most critical barrier in commercializing polymer electrolyte membrane fuel cell (PEMFC). In this work, Pt deposited N-doped mesoporous carbon derived from Aloe Vera is developed as an efficient and robust electro catalyst for ORR. Due to its high mesoporous nature, the aloe vera derived carbon (AVC) play a very vital role in supporting Pt nanoparticles (NPs) with N-doping. After doping N into AVC, more defects are created which facilitates uniform distribution of Pt NPs leading to more active sites towards ORR. Pt/N-AVC shows excellent ORR activity when compared with commercial Pt/C and showing a half wave potential (E1/2–0.87 V Vs. RHE) and reduction potential (Ered ~ 0.72 V Vs. RHE) towards ORR. Even after 30,000 potential cycles, Pt/N-AVC shows in its E1/2 only ~5 mV negative shift and lesser agglomeration of Pt NPs is seen in the catalyst. In membrane electrode assembly (MEA) fabrication, Pt/N-AVC as a cathode catalyst in a PEMFC fixture and performance were studied. The Pt/N-AVC shows good performance, which proves the potential application of this naturally available bio derived carbon, which serves as an excellent high durable support material in PEMFC. All these features show that the Pt/N-AVC is the most stable, efficient and suitable candidate for ORR catalyst.

Introduction

Recent years has seen a huge rise in clean and efficient sustainable energy storage and conversion systems with their extensive application range [1]. The ORR is the most significant cathodic reaction in devices with major contribution in the reaction potential towards its overall performance [2]. However, the large over potential and sluggish reaction kinetics impede the practical efficiency of these devices [3,4]. Hence, it is highly anticipated towards the development of an efficient ORR catalyst with improved kinetics and stability to overcome the barriers [1,5]. At the present scenario, the most trend setting catalysts such as platinum and platinum based alloys due to their renowned ORR activity; though, the scarcity pricing, derisory reserve and deprived electrochemical stability of the Pt catalyst have considerably limited its substantial applications [[6], [7], [8]]. In spite of that, considerable optimization is required to improve the catalytic activity along with cost effectiveness and stability issues [8]. One among them is to reduce the Pt loading and use highly active catalyst support without affecting the supporting materials requirements such as low cost, good electrical conductivity, strengthened metal-support interaction, high surface area and good resistance to corrosion [[9], [10], [11], [12], [13], [14]]. Knowingly, in the past decades, carbon doped with heteroatom's such as N [[15], [16], [17], [18]], S [19], F [16,20], P [15,21], and B [22] etc. were successively proved to best able and active support materials for Pt supported catalysts in ORR and implying the feasibility of lowering Pt usage effectively [17,[23], [24], [25]]. Depending on the doping of heteroatoms and texture of porous carbon that can enhance the surface hydrophilicity and feasible the active sites creation, which leads to an increased ORR reaction kinetics [10,[14], [15], [16],21,26]. Amongst, Nitrogen (N) shows attracting dopant in the carbon matrix due to its higher electrochemical stability and electron accepting ability. Especially Pt deposited on N-doped carbon nanomaterial shows remarkable enhancement in Pt usage, activity and stability [14]. Many studies, evidence the improved stability of Pt NPs on N-doped porous carbon through the preferred active forms of N atoms [17] and form dative bond with Pt metal (N–Pt) which improves the electrochemical stability and prevents the agglomeration of Pt NPs from the support. Different categories of N-doped allotropes of carbon have been noted such as carbon nanotubes [[27], [28], [29], [30], [31]], graphene [13,[32], [33], [34]], nanocoils [35], nanofibers [10,36,37], mesoporous carbon [8,17,38], and quantum dots [18,39,40]. Amongst all, carbon with mesopores (pore size 2–50 nm) are very attractive due to their pore geometry and lofty pore volume for the faster diffusion and an efficient mass transport [41].

Recently, porous carbon derived from bio sources has been environmentally most abundant, inexpensive, also provides an excellent platform to regulate porous structure with high surface area [5,[42], [43], [44]]. The synthesis of porous carbon from biomass is achieved via pyrolysis, gasification, hydrothermal carbonization, template-based methods, and soft template [14,19,[45], [46], [47]] etc. Among all these methods, direct pyrolysis drags attention owing to template–free loom, low cost, conservational, scalable, and to prepare hierarchically porous carbon, while comparing others observe difficulties such as complex and costly instruments, use of harmful chemicals etc. [48]. Numerous reports available in the literature pertaining porous carbon derived from various biomass sources viz. Jackfruit seed [42], cotton [20,49,50], coffee beans [51], spent coffee grounds [15,16], corncob [52,53], coconut shell [54], orange peel [55], wall nut [56] and aloe vera peels [57] towards the sustainable energy storage and conversion applications. The porous carbon derived from the above sources shows great influence on the catalytic properties such as electronic conductivity, catalytic activity, charge density and tuned electron distribution by creating active sites that are favourable for ORR [5,[58], [59], [60]]. The N-doped carbon with pyridinium nitrogen has a lone pair electron, which can modify the distribution of charge into the carbon matrix, the electron donating capability and effectively weaken the O–O band [34] favourable for the adsorption and activation of oxygen, boosting the ORR process [47,61]. The graphitic N is also favourable for the active sites and with the coexistence of different kinds of N present in the carbon matrix [33,62]. The amalgamation of nitrogen into the carbon matrix functionalize the carbon and helps interaction of Pt NPs through Pt–N–C and enhance the electronic conductivity, charge transfer etc. In this point of view, aloe vera peels derived nitrogen doped carbon drags the attention due to its abundance and production availability to make an efficient electro catalyst for ORR [57].

In this work, we synthesised porous carbon from naturally available aloe vera peel with nitrogen doping as exemplary support for Pt based ORR catalyst. The Pt/N-AVC has shown high durability and excellent electrochemical activity, directly crediting to the nitrogen content and the extremely porous support material. The Pt/N-AVC catalyst even after 30,000 potential cycling, the E1/2 shows only 5 mV negative shift and there is was no sign of agglomeration or dissolution of Pt NPs from the supporting material which indicates Pt/N-AVC catalyst as an excellent high durable cathode catalyst useful for PEMFC applications.

Section snippets

Experimental section

For the preparation of porous carbon from biomass, aloe vera plant leaf was collected from a plant and aloe vera peels were dried under sunlight for 36 h to remove the moisture content. The dried peel was cut into small pieces and kept for 24 h in the oven at 80 °C. Then the peels were pyrolyzed under the nitrogen atmosphere in a temperature range of 800–1000 °C for 1 h. The resultant black materials were further purified with 5 M aqueous HNO3 and washed thoroughly with deionised (DI) water

Structure and morphology

The preparation of bio-derived porous carbon from aloe vera plant leaf and its activation process significantly influence the intrinsic and extrinsic characteristics of as-prepared carbon. Fig. 1(a) illustrate the XRD pattern of AVC and N-AVC, which shows two distinct peaks at 2ϴ value belongs to the graphitic carbon of 24° and 43° analogous to (002) and (100) planes [16]. Pt deposition on N-AVC (Pt/N-AVC) show the crystalline Pt (0) NPs with the diffraction peaks were observed at 40°, 46.5°,

Conclusions

An efficient and durable Pt supported N-doped mesoporous carbon (Pt/N-AVC) catalyst has been successfully synthesised from the naturally available Aloe Vera plant by simple pyrolysis and the reduction method. Doping N into AVC matrix, the ID/IG ratio is increasing due to more defects, which are newly created, and this leads to an increase in the specific surface area (376 m2/g) and the volume. The well dispersion of Pt NPs is seen in HR-TEM images and the presence of N, C and Pt NPs are

Acknowledgements

This work was supported by Department of Science and Technology (DST), New Delhi, India for awarding INSPIRE Faculty Award (DST/INSPIRE/04/2016/000530). One of the authors, Dr. Prabu Moni grateful to the Department of Science and Technology (DST), New Delhi, India for awarding INSPIRE Faculty Award (DST/INSPIRE/04/2016/000530). We thank Dr. N. Kalaiselvi, Director, CSIR-CECRI, for the continuous encouragement and support.

References (81)

  • D. Kong et al.

    Synergistic effect of Nitrogen-doped hierarchical porous carbon/graphene with enhanced catalytic performance for oxygen reduction reaction

    Appl Surf Sci

    (2017)
  • R. Atchudan et al.

    Green synthesis of nitrogen-doped graphitic carbon sheets with use of Prunus persica for supercapacitor applications

    Appl Surf Sci

    (2017)
  • Y. Wang et al.

    Highly active and stable platinum catalyst supported on porous carbon nanofibers for improved performance of PEMFC

    Electrochim Acta

    (2015)
  • V. Parthiban et al.

    Sahu Fluorine-enriched mesoporous carbon as efficient oxygen reduction catalyst: understanding the defects in porous matrix and fuel cell applications

    Nanoscale Adv

    (2019)
  • M. Fan et al.

    Facile self-assembly N-doped graphene quantum dots/graphene for oxygen reduction reaction

    Electrochim Acta

    (2016)
  • P. Rupa Kasturi et al.

    Bio-derived carbon as an efficient supporting electrocatalyst for the oxygen reduction reaction

    J Phys Chem Solid

    (2019)
  • Y. Huang et al.

    Facile preparation of biomass-derived bifunctional electrocatalysts for oxygen reduction and evolution reactions

    Int J Hydrogen Energy

    (2018)
  • X. Li et al.

    A universal strategy for carbon–based ORR–active electrocatalyst: one porogen, two pore–creating mechanisms, three pore types

    Nanomater Energy

    (2019)
  • G. Cognard et al.

    Benefits and limitations of Pt nanoparticles supported on highly porous antimony-doped tin dioxide aerogel as alternative cathode material for proton-exchange membrane fuel cells

    Appl Catal B Environ

    (2017)
  • L. Chen et al.

    Cotton fabric derived hierarchically porous carbon and nitrogen doping for sustainable capacitor electrode

    Carbon

    (2017)
  • M. Karnan et al.

    Electrochemical studies on corncob derived activated porous carbon for supercapacitors application in aqueous and non-aqueous electrolytes

    Electrochim Acta

    (2017)
  • M. Borghei et al.

    Porous N,P-doped carbon from coconut shells with high electrocatalytic activity for oxygen reduction: alternative to Pt-C for alkaline fuel cells

    Appl Catal B Environ

    (2017)
  • X. Xu et al.

    Walnut shell derived porous carbon for a symmetric all-solid-state supercapacitor

    Appl Surf Sci

    (2017)
  • Z. Wang et al.

    Aloe peel-derived honeycomb-like bio-based carbon with controllable morphology and its superior electrochemical properties for new energy devices

    Ceram Int

    (2019)
  • F. Zheng et al.

    Biomass waste inspired nitrogen-doped porous carbon materials as high-performance anode for lithium-ion batteries

    J Alloys Compd

    (2017)
  • D. He et al.

    Simultaneous sulfonation and reduction of graphene oxide as highly efficient supports for metal nanocatalysts

    Carbon

    (2014)
  • W.S. Jung et al.

    Improved durability of Pt catalyst supported on N-doped mesoporous graphitized carbon for oxygen reduction reaction in polymer electrolyte membrane fuel cells

    Carbon

    (2017)
  • J. Zhu et al.

    Facile synthesis of boron and nitrogen-dual-doped graphene sheets anchored platinum nanoparticles for oxygen reduction reaction

    Electrochim Acta

    (2016)
  • G.-P. Kim et al.

    Polymer-mediated synthesis of a nitrogen-doped carbon aerogel with highly dispersed Pt nanoparticles for enhanced electrocatalytic activity

    Electrochim Acta

    (2016)
  • Y. Cheng et al.

    Fabricating Pt-decorated three dimensional N-doped carbon porous microspherical cavity catalyst for advanced oxygen reduction reaction

    Carbon

    (2018)
  • S. Ratso et al.

    Enhanced oxygen reduction reaction activity of iron-containing nitrogen-doped carbon nanotubes for alkaline direct methanol fuel cell application

    J Power Sources

    (2016)
  • D. Puthusseri et al.

    Oxygen reduction reaction activity of platinum nanoparticles decorated nitrogen doped carbon in proton exchange membrane fuel cell under real operating conditions

    Int J Hydrogen Energy

    (2016)
  • H.A.B.M.D. Weththasinha et al.

    Nitrogen doped lotus stem carbon as electrocatalyst comparable to Pt/C for oxygen reduction reaction in alkaline media

    Int J Hydrogen Energy

    (2017)
  • J. Ying et al.

    Metal-organic frameworks derived platinum-cobalt bimetallic nanoparticles in nitrogen-doped hollow porous carbon capsules as a highly active and durable catalyst for oxygen reduction reaction

    Appl Catal B Environ

    (2018)
  • R. Brandiele et al.

    Probing the correlation between Pt-support interaction and oxygen reduction reaction activity in mesoporous carbon materials modified with Pt-N active sites

    Electrochim Acta

    (2018)
  • Q. Zhang et al.

    Ultrathin nitrogen doped carbon layer stabilized Pt electrocatalyst supported on N-doped carbon nanotubes

    Int J Hydrogen Energy

    (2017)
  • J.-Y. Park et al.

    Enhanced oxygen reduction reaction of Pt deposited Fe/N-doped bimodal porous carbon nanostructure catalysts

    J Catal

    (2018)
  • H.S. Kim et al.

    Platinum catalysts protected by N-doped carbon for highly efficient and durable polymer-electrolyte membrane fuel cells

    Electrochim Acta

    (2016)
  • S.G. Peera et al.

    Platinum nanoparticles supported on nitrogen and fluorine co-doped graphite nanofibers as an excellent and durable oxygen reduction catalyst for polymer electrolyte fuel cells

    Carbon

    (2016)
  • Y. Wang et al.

    Catalysis with two-dimensional materials confining single atoms: concept, design, and applications

    Chem Rev

    (2019)
  • Cited by (34)

    View all citing articles on Scopus
    View full text