- Nano Express
- Open Access
Heavily Graphitic-Nitrogen Self-doped High-porosity Carbon for the Electrocatalysis of Oxygen Reduction Reaction
© The Author(s). 2017
- Received: 18 July 2017
- Accepted: 5 November 2017
- Published: 17 November 2017
Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics. Our results can encourage the synthesis of high-performance carbon-based ORR electrocatalysts derived from widely-existed natural biomass.
- Kidney bean
- High porosity
- Carbon material
- Oxygen reduction reaction
Platinum (Pt)-based materials, the state-of-the-art catalysts for fuel cells, suffer from expensive price, limited resources, insufficient durability, and methanol-tolerant property in electrocatalysis process of oxygen reduction reaction (ORR) . Great efforts were recently devoted to search for highly active, durable, and inexpensive alternatives to Pt-based ORR electrocatalysts for this purpose . Among the various non-Pt catalysts, heteroatom-doped porous carbons (HDPC) are a new type of metal-free catalysts with high activity and durability for ORR thanks to their low-cost, non-toxicity, and renewability [3–6], and thus, the in-depth researches are eagerly anticipated to date. HDPC is generally synthesized by chemical methods or natural templates, but they cannot meet the requirements of low-cost, easy-to-synthesis, and excellent performance [7, 8]. Therefore, the search for a reasonable and effective method to synthesize the HDPC material is still a significant scientific issue for realizing highly-efficient catalysis for oxygen reduction.
As previously reported, protein-enriched biomass (e.g., nori , sweet potato vine , pomelo peel , enoki mushroom , coprinus comatus , and Lemna minor ) can be widely used a single-source precursor for HDPC catalyst towards the ORR. We recently propose some strategy to form the HDPC catalyst with porous 3D-network structure via high-temperature carbonization of fish-scale biowaste with an activator of zinc chloride . We interestingly find that the first-step pretreatment of biomass can not only help to improve the characteristics of carbon structure of final ORR catalyst, but also increases its surface nitrogen content and doping efficiency of nitrogen atoms into carbon structure. Based on this finding, here, we first report a strategy to fabricate heavily graphitic-nitrogen-doped porous carbons (KB350Z-900) by directly converting white kidney bean (KB) biomass with a process of two-step carbonization, followed by zinc chloride activation, and acidic-treatment process. The KB biomass, which is one of the most famous edible beans today, can be abundantly and cheaply obtained in various countries. The total content of biological protein in dehydrated KB biomass is 20–30% generally. To the best of our knowledge, there is seldom reported on the ORR activity of the doped carbon catalyst derived from KB biomass. The role of ZnCl2 in the activation process can mainly spur the rapid dehydration and catalytic dehydroxylation of KB biomass so that the hydrogen and oxygen inside the KB biomass are released in the formation of water vapor. This process can facilitate the formation of more micro/meso-pores, finally producing nitrogen self-doped high-porosity carbon materials. The obtained carbon-based catalyst exhibits high electrocatalytic activity, long-term durability, and methanol-tolerant property, which may be a promising alternative to the Pt-based catalyst towards the ORR in alkaline medium.
First, white kidney bean (KB) was washed by deionized water and completely dried at 80 °C in a vacuum drying oven. Subsequently, KB was pretreated in flowing-N2 atmosphere at 350 °C for 2 h for effective decomposition of protein to yield the KB350 precursor. Although the fastest decomposition of white KB biomass occurs at about 300 °C (Additional file 1: Figure S1), but a temperature of 350 °C was chosen as the first-step carbonization temperature in order to exceed the decomposition temperature of tyrosine (344 °C), the highest among the amino acids in bioprotein. KB350 and zinc chloride (ZnCl2) were mechanically mixed by ball-milling at 500 rpm according to mass ratio of 1:1. The obtained mixture was pyrolyzed in a tubular furnace at different temperatures (700, 800, 900, or 1000 °C) for 2 h with a heating-rate of 10 °C min− 1. The produced nanocarbon is hereafter called KB350Z-X (X = 700, 800, 900, or 1000). As a control, the KB-Z-900 was similarly fabricated by pyrolyzing a mechanical mixture of KB and ZnCl2 with the same mass ratio. Direct pyrolysis of KB at 900 °C for 2 h was utilized to prepare the KB900. All prepared samples were further post-treated in 0.5 mol l− 1 HCl solution for 2 h. The aim of acid-leaching is to effectively remove Zn species and metallic impurities before electrochemical testing.
Raman spectroscopy data were tested with a Renishaw inVia unit with an excited-λ of 514.5 nm. Field-emission scanning electron microscopy (FE-SEM) images were obtained by Hitachi UHR S4800 (Japan). High-resolution transmission electron microscopy (HR-TEM) was carried out on FEI Tecnai F30 instrument and acceleration voltage is 300 kV. X-ray photoelectron spectroscopy (XPS) was carried out using a Kratos XSAM800 spectrometer. A Micromeritics Analyzer (ASAP 2010) was applied to measure N2 adsorption/desorption isotherms at 77 K.
Electrochemical measurements were performed on a Zennium-E workstation (Germany) with a conventional three-electrode system. A glass-carbon rotation disk electrode (GC-RDE, Φ = 4 mm, Model 636-PAR), a saturated calomel electrode (SCE), and a graphite rod (Φ = 0.5 cm) were used as working electrode, reference electrode, and auxiliary electrode, respectively. The fabrication of working electrode refers to our previous reports . Generally, 5.0 μl of 10 mg ml− 1 dispersion was transferred onto the GC-RDE surface and dried naturally. The mass loading of all tested samples was controlled to be ~ 400 μg cm− 2. All potentials (versus SCE) were transformed into the potentials versus the reversible hydrogen electrode (RHE).
Here, we use the accelerated aging test (AAT) by CV continuous scanning for 5000 cycles on a potential range of 0.2 to 1.2 V versus RHE to evaluate the electrochemical stability of KB350Z-900 and Pt/C catalyst in an O2-saturated KOH electrolyte. After CV testing, the half-wave potential of the ORR on the KB350Z-900-catalyzed electrode is negatively shifted by only 2 mV, but the reduced half-wave potential of the ORR on the JM Pt/C-catalyzed electrode is about 55 mV (Fig. 4d). Additionally, a higher degradation in limited current density is also found for Pt/C catalyst, indicating more excellent electrocatalytic stability of KB350Z-900 towards the ORR. Amperometric i-t curves at 0.9 V in O2-saturated KOH electrolyte (inset of Fig. 4d) confirm that the electro-oxidation reaction of 3 M methanol hardly occurs at KB350Z-900, suggesting a good methanol-tolerant performance of KB350Z-900 and the promising applications in alkaline methanol fuel cells.
Herein, we develop a facile and easy method to the large-scale production of high-porosity carbons doped with heavily graphitic nitrogen from two-step pyrolysis of kidney bean biomass combining with the activation of zinc chloride and acid-treatment process, which can be functioned as an oxygen reduction electrocatalyst in alkaline medium. First, we find that a large BET surface area (~ 1132 m2 g− 1) can be obtained at KB350Z-900 with a high pore volume of ~ 0.62 m3 g− 1. Secondly, two-step pyrolysis process with zinc chloride activation can help to significantly increase the content of graphitic nitrogen inside the carbon-based catalyst. We also observe that the ORR catalytic activity of this carbon material can compare favorably with that of the state-of-the-art commercial 20 wt.% Pt/C catalyst, but also the former’s electrocatalysis stability to the ORR and methanol-tolerant performance are better, suggesting a promising applications in alkaline fuel cells. The excellent ORR performance of KB350Z-900 can be mainly owing to high content of graphitic nitrogen, high specific surface area, and porous characteristics. Our results can further promote the large-scale production of highly active and stable carbon-based ORR electrocatalysts derived from widely-existed natural biomass.
We thank Prof. Changguo Chen, Yujun Si, Zhongli Luo, and Jiahong He for helping us with English language correction and performing some characterization experiments.
This work was financially supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJ1711289, KJ1711285, KJ1501118), the Natural Science Foundation of Yongchuan Science and Technology Commission of Chongqing (Ycstc, 2016nc6001), the Natural Science Foundation of Chongqing Municipal Science and Technology Commission (cstc2015jcyjA50032, cstc2014jcyjA50038), the Foundation for High-level Talents of Chongqing University of Art and Sciences (R2014CJ02), the Scientific Research Program of Chongqing University of Arts and Sciences (P2016XC07), and the Innovation Team Project of Chongqing Municipal Education Commission (CXTDX201601037).
TF, WL, and ZL carried out the electrochemical experiments and wrote the manuscript. LS, TL, YH, YW, JC, and YL prepared the samples and performed the characterizations. CG and QD provided the idea for this work and revised the manuscript. All authors read and approved the final manuscript.
Chaozhong Guo received his Ph.D. at Chongqing University of China in 2013. He is a distinguished second-class professor and master supervisor of chemical engineering and tip-top academic backbone at Chongqing University of Arts and Sciences. His research focuses on green synthesis of nanocarbon-based electrocatalysts in energy conversion and storage. Currently, he has authored about 30 papers in peer-reviewed journals (e.g., Nanoscale, Carbon, Journal of Power Sources, Electrochimica Acta).
Qizhi Diao received his M.S. degree at Chongqing Medical University of China in 2007. He is a professor and master supervisor of bio-electrochemistry at Chongqing Medical University. His research mainly focuses on green synthesis of nanocarbon composites for biosensor.
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- Dai L, Xue Y, Qu L, Choi H-J, Baek J-B (2015) Metal-free catalysts for oxygen reduction reaction. Chem Rev 115:4823–4892View ArticleGoogle Scholar
- Wu G, Zelenay P (2013) Nanostructured nonprecious metal catalysts for oxygen reduction reaction. Accounts Chem Res 46:1878–1889View ArticleGoogle Scholar
- Vij V, Tiwari JN, Lee W-G, Yoon T, Kim KS (2016) Hemoglobin-carbon nanotube derived noble-metal-free Fe5C2-based catalyst for highly efficient oxygen reduction reaction. Sci Rep 6:20132View ArticleGoogle Scholar
- Nie Y, Xie X, Chen S, Ding W, Qi X, Wang Y, Wang J, Li W, Wei Z, Shao M (2016) Towards effective utilization of nitrogen-containing active sites: nitrogen-doped carbon layers wrapped CNTs electrocatalysts for superior oxygen reduction. Electrochim Acta 187:153–160View ArticleGoogle Scholar
- Guo C, Wen B, Liao W, Li Z, Sun L, Wang C, Wu Y, Chen J, Nie Y, Liao J, Chen C (2016) Template-assisted conversion of aniline nanopolymers into non-precious metal FeN/C electrocatalysts for highly efficient oxygen reduction reaction. J Alloys Compd 686:874–882View ArticleGoogle Scholar
- Guo C, Hu R, Liao W, Li Z, Sun L, Shi D, Li Y, Chen C (2017) Protein-enriched fish “biowaste” converted to three-dimensional porous carbon nano-network for advanced oxygen reduction electrocatalysis. Electrochim Acta 236:228–238View ArticleGoogle Scholar
- Guo C-Z, Liao WL, Chen C-G (2014) Design of a non-precious metal electrocatalyst for alkaline electrolyte oxygen reduction by using soybean biomass as the nitrogen source of electrocatalytically active center structures. J Power Sources 269:841–847View ArticleGoogle Scholar
- Ding W, Wei Z, Chen S, Wei Z (2013) Space-confinement-induced synthesis of pyridinic- and pyrrolic-nitrogen-doped graphene for the catalysis of oxygen reduction. Angew Chem Int Ed 52:11755–11759View ArticleGoogle Scholar
- Liu F, Peng H, You C, Liao S (2014) High-performance doped carbon catalyst derived from nori biomass with melamine promoter. Electrochim Acta 138:353–359View ArticleGoogle Scholar
- Gao S, Li L, Geng K, Wei X, Zhang S (2015) Recycling the biowaste to produce nitrogen and sulfur self-doped porous carbon as an efficient catalyst for oxygen reduction reaction. Nano Energy 16:408–418View ArticleGoogle Scholar
- Yuan W, Feng Y, Xie A, Zhang X, Huang F, Li S, Zhang X, Shen Y (2016) Nitrogen-doped nanoporous carbon derived from waste pomelo peel as a metal-free electrocatalyst for the oxygen reduction reaction. Nanoscale 8:8704–8711Google Scholar
- Guo C, Liao W, Li Z, Sun L, Chen C (2015) Easy conversion of protein-rich enoki mushroom biomass to a nitrogen-doped carbon nanomaterial as a promising metal-free catalyst for oxygen reduction reaction. Nano 7:15990–15998Google Scholar
- Guo C, Liao W, Li Z, Sun L, Ruan H, Wu Q, Luo Q, Huang J, Chen C (2016) Coprinus comatus-derived nitrogen-containing biocarbon electrocatalyst with the addition of self-generating graphene-like support for superior oxygen reduction reaction. Sci Bull 61:948–958View ArticleGoogle Scholar
- Li Y, Liao W, Li Z, Feng T, Sun L, Guo C, Zhang J, Li J (2017) Building three-dimensional porous nano-network for the improvement of iron and nitrogen-doped carbon oxygen reduction electrocatalyst. Carbon 125:640–648View ArticleGoogle Scholar
- Jin H, Zhang H, Zhong H, Zhang J (2011) Nitrogen-doped carbon xerogel: a novel carbon-based electrocatalyst for oxygen reduction reaction in proton exchange membrane (PEM) fuel cells. Energy Environ Sci 4:3389–3394View ArticleGoogle Scholar
- Rao CV, Cabrera CR, Ishikawa Y (2010) In search of the active site in nitrogen-doped carbon nanotube electrodes for the oxygen reduction reaction. J Phys Chem Lett 1:2622–2627View ArticleGoogle Scholar
- Wang L, Tang Z, Yan W, Yang H, Wang Q, Chen S (2016) Porous carbon-supported gold nanoparticles for oxygen reduction reaction: effects of nanoparticle size. ACS Appl Mater Interfaces 8:20635–20641View ArticleGoogle Scholar
- Wang L, Tang Z, Yan W, Wang Q, Yang H, Chen S (2017) Co@pt core@shell nanoparticles encapsulated in porous carbon derived from zeolitic imidazolate framework for oxygen electroreduction in alkaline media. J Power Sources 343:458–466View ArticleGoogle Scholar
- Li Y, Guo C, Li J, Liao W, Li Z, Zhang J, Chen C (2017) Pyrolysis-induced synthesis of iron and nitrogen-containing carbon nanolayers modified graphdiyne nanostructure as a promising core-shell electrocatalyst for oxygen reduction reaction. Carbon 119:201–210View ArticleGoogle Scholar
- Bard AJ, Faulkner L (2001) Electrochemical methods, second edn. Wiley & Sons, New YorkGoogle Scholar
- Fu X, Liu Y, Cao X, Jin J, Liu Q, Zhang J (2013) FeCo–N x embedded graphene as high performance catalysts for oxygen reduction reaction. Appl Catal B 130-131:143–151View ArticleGoogle Scholar