• Nano Fe2O3 and N-doped graphene was prepared via a one-step ball milling method.
• The maximum power density of Fe-N-G in MFC was 390% of that of pristine graphite.
• Active sites like nano Fe2O3, pyridinic N and Fe-N groups were formed in Fe-N-G.
• The improvement of Fe-N-G was due to full exposure of active sites on graphene.
Developing high activity, low-cost and long durability catalysts for oxygen reduction reaction is of great significance for the practical application of microbial fuel cells. The full exposure of active sites in catalysts can enhance catalytic activity dramatically. Here, novel Fe-N-doped graphene is successfully synthesized via a one-step in situ ball milling method. Pristine graphite, ball milling graphene, N-doped graphene and Fe-N-doped graphene are applied in air cathodes, and enhanced performance is observed in microbial fuel cells with graphene-based catalysts. Particularly, Fe-N-doped graphene achieves the highest oxygen reduction reaction activity, with a maximum power density of 1380±20 mW/m2 in microbial fuel cells and a current density of 23.8 A/m2 at –0.16 V in electrochemical tests, which are comparable to commercial Pt and 390% and 640% of those of pristine graphite. An investigation of the material characteristics reveals that the superior performance of Fe-N-doped graphene results from the full exposure of Fe2O3 nanoparticles, pyrrolic N, pyridinic N and excellent Fe-N-G active sites on the graphene matrix. This work not only suggests the strategy of maximally exposing active sites to optimize the potential of catalysts but also provides promising catalysts for the use of microbial fuel cells in sustainable energy generation.
A Jain, Z He (2018). “NEW” resource recovery from wastewater using bioelectrochemical systems: Moving forward with functions. Frontiers of Environmental Science & Engineering, 12(4): 3–15 https://doi.org/10.1007/s11783-018-1052-9
C Cao, L Wei, G Wang, J Shen (2017a). Superiority of boron, nitrogen and iron ternary doped carbonized graphene oxide-based catalysts for oxygen reduction in microbial fuel cells. Nanoscale, 9(10): 3537–3546 https://doi.org/10.1039/C7NR00869D
pmid: 28244536
4
C Cao, L Wei, Q Zhai, J Ci, W Li, G Wang, J Shen (2017b). Gas-flow tailoring fabrication of graphene-like Co–Nx–C nanosheet supported sub-10 nm PtCo nanoalloys as synergistic catalyst for air-cathode microbial fuel cells. ACS Applied Materials & Interfaces, 9(27): 22465–22475 https://doi.org/10.1021/acsami.7b04564
pmid: 28665104
5
X Chen, F Li, N Zhang, L An, D Xia (2013). Mechanism of oxygen reduction reaction catalyzed by Fe(Co)-Nx/C. Physical chemistry chemical physics, 15(44): 19330–19336 https://doi.org/10.1039/c3cp52802b
pmid: 24121394
6
Z Chen, D Higgins, A Yu, L Zhang, J Zhang (2011). A review on non-precious metal electrocatalysts for PEM fuel cells. Energy & Environmental Science, 4(9): 3167–3192 https://doi.org/10.1039/c0ee00558d
7
Z Y Chen, Y N Li, L L Lei, S J Bao, M Q Wang, H Liu, Z L Zhao, M Xu (2017). Investigation of Fe2N@Carbon encapsulated in N-doped graphene-like carbon as a catalyst in sustainable zinc-air batteries. Catalysis Science & Technology, 7(23): 5670–5676 https://doi.org/10.1039/C7CY01721A
8
C H Choi, W S Choi, O Kasian, A K Mechler, M T Sougrati, S Brüller, K Strickland, Q Jia, S Mukerjee, K J J Mayrhofer, F Jaouen (2017). Unraveling the nature of sites active toward hydrogen peroxide reduction in Fe-N-C catalysts. Angewandte Chemie International Edition, 56(30): 8809–8812 https://doi.org/10.1002/anie.201704356
pmid: 28570025
9
N D Chuong, T D Thanh, N H Kim, J H Lee (2018). Hierarchical heterostructures of ultrasmall Fe2O3-encapsulated MoS2/N-graphene as an effective catalyst for oxygen reduction reaction. ACS Applied Materials & Interfaces, 10(29): 24523–24532 https://doi.org/10.1021/acsami.8b06485
pmid: 29972302
10
F G Durán, B P Barbero, L E Cadús, C Rojas, M A Centeno, J A Odriozola (2009). Manganese and iron oxides as combustion catalysts of volatile organic compounds. Applied Catalysis B: Environmental, 92(1-2): 194–201 https://doi.org/10.1016/j.apcatb.2009.07.010
11
A C Ferrari, J C Meyer, V Scardaci, C Casiraghi, M Lazzeri, F Mauri, S Piscanec, D Jiang, K S Novoselov, S Roth, A K Geim (2006). Raman spectrum of graphene and graphene layers. Physical Review Letters, 97(18): 187401(1)-187401(4) https://doi.org/10.1103/PhysRevLett.97.187401
pmid: 17155573
12
D Guo, R Shibuya, C Akiba, S Saji, T Kondo, J Nakamura (2016). Active sites of nitrogen-doped carbon materials for oxygen reduction reaction clarified using model catalysts. Science, 351(6271): 361–365 https://doi.org/10.1126/science.aad0832
pmid: 26798009
13
X Guo, J Jia, H Dong, Q Wang, T Xu, B Fu, R Ran, P Liang, X Huang, X Zhang (2019a). Hydrothermal synthesis of Fe-Mn bimetallic nanocatalysts as high-efficiency cathode catalysts for microbial fuel cells. Journal of Power Sources, 414: 444–452 https://doi.org/10.1016/j.jpowsour.2019.01.024
14
D He, Y Xiong, J Yang, X Chen, Z Deng, M Pan, Y Li, S Mu (2017). Nanocarbon-intercalated and Fe–N-codoped graphene as a highly active noble-metal-free bifunctional electrocatalyst for oxygen reduction and evolution. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 5(5): 1930–1934 https://doi.org/10.1039/C5TA09232A
15
M M Hossen, K Artyushkova, P Atanassov, A Serov (2018). Synthesis and characterization of high performing Fe-N-C catalyst for oxygen reduction reaction (ORR) in Alkaline Exchange Membrane Fuel Cells. Journal of Power Sources, 375: 214–221 https://doi.org/10.1016/j.jpowsour.2017.08.036
16
K Huang, L Zhang, T Xu, H Wei, R Zhang, X Zhang, B Ge, M Lei, J-Y Ma, L-M Liu, H Wu (2019). 60 °C solution synthesis of atomically dispersed cobalt electrocatalyst with superior performance. Nature Communications,10(1): 606(601–610)
17
C Jiang, L Liu, J C Crittenden. (2016). An electrochemical process that uses an Fe0/TiO2 cathode to degrade typical dyes and antibiotics and a bio-anode that produces electricity. Frontiers of Environmental Science & Engineering, 10(4): 25–32 https://doi.org/10.1007/s11783-016-0860-z
18
Z J Jiang, Z Jiang, W Chen (2014). The role of holes in improving the performance of nitrogen-doped holey graphene as an active electrode material for supercapacitor and oxygen reduction reaction. Journal of Power Sources, 251: 55–65 https://doi.org/10.1016/j.jpowsour.2013.11.031
19
L Lai, J R Potts, D Zhan, L Wang, C K Poh, C Tang, H Gong, Z Shen, J Lin, R S Ruoff (2012). Exploration of the active center structure of nitrogen-doped graphene-based catalysts for oxygen reduction reaction. Energy & Environmental Science, 5(7): 7936–7942 https://doi.org/10.1039/c2ee21802j
20
Q Li, W Chen, H Xiao, Y Gong, Z Li, L Zheng, X Zheng, W Yan, W C Cheong, R Shen, N Fu, L Gu, Z Zhuang, C Chen, D Wang, Q Peng, J Li, Y Li (2018). Fe isolated single atoms on S, N codoped carbon by copolymer pyrolysis strategy for highly efficient oxygen reduction reaction. Advanced materials, 30(25): 1800588 https://doi.org/10.1002/adma.201800588
pmid: 29726038
21
W Liang, J Chen, Y Liu, S Chen (2014). Density-functional-theory calculation analysis of active sites for four-electron reduction of O2 on Fe/N-doped graphene. ACS Catalysis, 4(11): 4170–4177 https://doi.org/10.1021/cs501170a
22
T Lin, Y Tang, Y Wang, H Bi, Z Liu, F Huang, X Xie, M Jiang (2013). Scotch-tape-like exfoliation of graphite assisted with elemental sulfur and graphene–sulfur composites for high-performance lithium-sulfur batteries. Energy & Environmental Science, 6(4): 1283–1290 https://doi.org/10.1039/c3ee24324a
23
Q Liu, Y Zhou, S Chen, Z Wang, H Hou, F Zhao (2015). Cellulose-derived nitrogen and phosphorus dual-doped carbon as high performance oxygen reduction catalyst in microbial fuel cell. Journal of Power Sources, 273: 1189–1193 https://doi.org/10.1016/j.jpowsour.2014.09.102
Y Liu, H Liu, C Wang, S X Hou, N Yang (2013). Sustainable energy recovery in wastewater treatment by microbial fuel cells: Stable power generation with nitrogen-doped graphene cathode. Environmental Science & Technology, 47(23): 13889–13895 https://doi.org/10.1021/es4032216
pmid: 24219223
26
Y Liu, Y Zhao, K Li, Z Wang, P Tian, D Liu, T Yang, Wang J (2018). Activated carbon derived from chitosan as air cathode catalyst for high performance in microbial fuel cells. Journal of Power Sources, 378: 1–9 https://doi.org/10.1016/j.jpowsour.2017.12.019
27
X Lu, Y Zeng, M Yu, T Zhai, C Liang, S Xie, M S Balogun, Y Tong (2014). Oxygen-deficient hematite nanorods as high-performance and novel negative electrodes for flexible asymmetric supercapacitors. Advanced materials, 26(19): 3148–3155 https://doi.org/10.1002/adma.201305851
pmid: 24496961
M Nadeem, G Yasin, M H Bhatti, M Mehmood, M Arif, L Dai (2018). Pt-M bimetallic nanoparticles (M= Ni, Cu, Er) supported on metal organic framework-derived N-doped nanostructured carbon for hydrogen evolution and oxygen evolution reaction. Journal of Power Sources, 402: 34–42 https://doi.org/10.1016/j.jpowsour.2018.09.006
30
Y Niu, X Huang, W Hu (2016). Fe3C nanoparticle decorated Fe/N doped graphene for efficient oxygen reduction reaction electrocatalysis. Journal of Power Sources, 332: 305–311 https://doi.org/10.1016/j.jpowsour.2016.09.130
31
W D Oh, G Lisak, R D Webster, Y N Liang, A Veksha, A Giannis, G S Moo, J W Lim, T T Lim (2018). Insights into the thermolytic transformation of lignocellulosic biomass waste to redox-active carbocatalyst: Durability of surface active sites. Applied Catalysis B: Environmental, 233: 120–129 https://doi.org/10.1016/j.apcatb.2018.03.106
32
L Qu, Y Liu, J B Baek, L Dai (2010). Nitrogen-doped graphene as efficient metal-free electrocatalyst for oxygen reduction in fuel cells. ACS Nano, 4(3): 1321–1326 https://doi.org/10.1021/nn901850u
pmid: 20155972
33
G Ren, Y Li, Z Guo, G Xiao, Y Zhu, L Dai, L Jiang (2015). A bio-inspired Co3O4-polypyrrole-graphene complex as an efficient oxygen reduction catalyst in one-step ball milling. Nano Research, 8(11): 3461–3471 https://doi.org/10.1007/s12274-015-0844-5
34
C Santoro, C Arbizzani, B Erable, I Ieropoulos (2017). Microbial fuel cells: From fundamentals to applications: A review. Journal of Power Sources, 356: 225–244 https://doi.org/10.1016/j.jpowsour.2017.03.109
pmid: 28717261
J Stacy, Y N Regmi, B Leonard, M Fan (2017). The recent progress and future of oxygen reduction reaction catalysis: A review. Renewable & Sustainable Energy Reviews, 69: 401–414 https://doi.org/10.1016/j.rser.2016.09.135
37
M Sun, L F Zhai, W W Li, H Q Yu (2016). Harvest and utilization of chemical energy in wastes by microbial fuel cells. Chemical Society Reviews, 45(10): 2847–2870 https://doi.org/10.1039/C5CS00903K
pmid: 26936021
38
H Tang, S Cai, S Xie, Z Wang, Y Tong, M Pan, X Lu (2016). Metal–organic‐framework‐derived dual metal‐ and nitrogen‐doped carbon as efficient and robust oxygen reduction reaction catalysts for microbial fuel cells. Advanced science, 3(2): 1500265 doi:10.1002/advs.201500265
pmid: 27774391
39
G Tian, Q Zhang, B Zhang, Y Jin, J Huang, D S Su, F Wei (2014). Toward full exposure of “active sites”: Nanocarbon electrocatalyst with surface enriched nitrogen for superior oxygen reduction and evolution reactivity. Advanced Functional Materials, 24(38): 5956–5961 https://doi.org/10.1002/adfm.201401264
40
Q Wang, Y Lei, Z Chen, N Wu, Y Wang, B Wang, Y Wang (2018). Fe/Fe3C@C nanoparticles encapsulated in N-doped graphene–CNTs framework as an efficient bifunctional oxygen electrocatalyst for robust rechargeable Zn–air batteries. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 6(2): 516–526 https://doi.org/10.1039/C7TA08423D
41
Q Wang, X Zhang, R Lv, X Chen, B Xue, P Liang, X Huang (2016). Binder-free nitrogen-doped graphene catalyst air-cathodes for microbial fuel cells. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 4(32): 12387–12391 https://doi.org/10.1039/C6TA03642B
42
X Xia, F Zhang, X Zhang, P Liang, X Huang, B E Logan (2013). Use of pyrolyzed iron ethylenediaminetetraacetic acid modified activated carbon as air-cathode catalyst in microbial fuel cells. ACS Applied Materials & Interfaces, 5(16): 7862–7866 https://doi.org/10.1021/am4018225
pmid: 23902951
43
M Xiao, J Zhu, L Ma, Z Jin, J Ge, X Deng, Y Hou, Q He, J Li, Q Jia, S Mukerjee, R Yang, Z Jiang, D Su, C Liu, W Xing (2018). Microporous framework induced synthesis of single-atom dispersed Fe-N-C acidic ORR catalyst and its in situ reduced Fe-N4 active site identification revealed by X-ray absorption Spectroscopy. ACS Catalysis, 8(4): 2824–2832 https://doi.org/10.1021/acscatal.8b00138
44
W Yang, J Li, D Ye, X Zhu, Q Liao (2017). Bamboo charcoal as a cost-effective catalyst for an air-cathode of microbial fuel cells. Electrochimica Acta, 224: 585–592 https://doi.org/10.1016/j.electacta.2016.12.046
45
H Yin, C Zhang, F Liu, Y Hou (2014). Doped graphene: Hybrid of iron nitride and nitrogen‐doped graphene aerogel as synergistic catalyst for oxygen reduction reaction. Advanced Functional Materials, 24(20): 2930–2937 https://doi.org/10.1002/adfm.201470130
46
H Yuan, Y Hou, Aub- I M A Reesh, J Chen, Z He (2016). Oxygen reduction reaction catalysts used in microbial fuel cells for energy-efficient wastewater treatment: A review. Materials Horizons, 3(5): 382–401 https://doi.org/10.1039/C6MH00093B
47
B Zhang, Z Wen, S Ci, S Mao, J Chen, Z He (2014a). Synthesizing nitrogen-doped activated carbon and probing its active sites for oxygen reduction reaction in microbial fuel cells. ACS Applied Materials & Interfaces, 6(10): 7464–7470 https://doi.org/10.1021/am5008547
pmid: 24720600
48
L Zhang, Y Ni, X Wang, G Zhao (2010). Direct electrocatalytic oxidation of nitric oxide and reduction of hydrogen peroxide based on-Fe2O3 nanoparticles-chitosan composite. Talanta, 82(1): 196–201 https://doi.org/10.1016/j.talanta.2010.04.018
pmid: 20685456
49
X Zhang, D Pant, F Zhang, J Liu, W He, B E Logan (2014b). Long-term performance of chemically and physically modified activated carbons in air cathodes of microbial fuel cells. ChemElectroChem, 1(11): 1859–1866 https://doi.org/10.1002/celc.201402123
50
X Zhang, X Xia, I Ivanov, X Huang, B E Logan (2014c). Enhanced activated carbon cathode performance for microbial fuel cell by blending carbon black. Environmental Science & Technology, 48(3): 2075–2081 https://doi.org/10.1021/es405029y
pmid: 24422458
51
Q Zhao, H Yu, W Zhang, F T Kabutey, J Jiang, Y Zhang, K Wang, J Ding (2017). Microbial fuel cell with high content solid wastes as substrates: A review. Frontiers of Environmental Science & Engineering, 11(2): 25-41 https://doi.org/10.1007/s11783-017-0918-6
52
Z Y Wu, X X Xu, B C Hu, H W Liang, Y Lin, L F Chen, S H Yu (2015). Iron carbide nanoparticles encapsulated in mesoporous Fe-N-doped carbon nanofibers for efficient electrocatalysis. Angewandte Chemie (International ed. in English), 54(28): 8179–8183 https://doi.org/10.1002/anie.201502173
pmid: 26014581
53
S Zhuang, E S Lee, L Lei, B B Nunna, L Kuang, W Zhang (2016). Synthesis of nitrogen‐doped graphene catalyst by high‐energy wet ball milling for electrochemical systems. International Journal of Energy Research, 40(15): 2136–2149 https://doi.org/10.1002/er.3595
54
S Zhuang, B B Nunna, E S Lee (2018). Metal organic framework-modified nitrogen-doped graphene oxygen reduction reaction catalyst synthesized by nanoscale high-energy wet ball-milling structural and electrochemical characterization. MRS Communications, 8(01): 40–48 https://doi.org/10.1557/mrc.2017.130
55
A Zitolo, V Goellner, V Armel, M T Sougrati, T Mineva, L Stievano, E Fonda, F Jaouen (2015). Identification of catalytic sites for oxygen reduction in iron- and nitrogen-doped graphene materials. Nature Materials, 14(9): 937–942 https://doi.org/10.1038/nmat4367
pmid: 26259106
