Review Article | Published:

Carbon-based metal-free catalysts

Nature Reviews Materials volume 1, Article number: 16064 (2016) | Download Citation

  • An Erratum to this article was published on 04 October 2016

Abstract

Metals and metal oxides are widely used as catalysts for materials production, clean energy generation and storage, and many other important industrial processes. However, metal-based catalysts suffer from high cost, low selectivity, poor durability, susceptibility to gas poisoning and have a detrimental environmental impact. In 2009, a new class of catalyst based on earth-abundant carbon materials was discovered as an efficient, low-cost, metal-free alternative to platinum for oxygen reduction in fuel cells. Since then, tremendous progress has been made, and carbon-based metal-free catalysts have been demonstrated to be effective for an increasing number of catalytic processes. This Review provides a critical overview of this rapidly developing field, including the molecular design of efficient carbon-based metal-free catalysts, with special emphasis on heteroatom-doped carbon nanotubes and graphene. We also discuss recent advances in the development of carbon-based metal-free catalysts for clean energy conversion and storage, environmental protection and important industrial production, and outline the key challenges and future opportunities in this exciting field.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , , , & Nitrogen-doped carbon nanotube arrays with high electrocatalytic activity for oxygen reduction. Science 323, 760–764 (2009). The first metal-free catalyst (nitrogen-doped VA-CNT) that showed superior ORR activity to commercial Pt/C.

  2. 2.

    , , & N-Doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells. Sci. Adv. 1, e1400129 (2015). The first metal-free catalyst (nitrogen-doped graphene CNT) that showed long-term operational stabilities and comparable gravimetric power densities to the best non-precious metal catalysts in acidic PEM cells.

  3. 3.

    , , , & Nitrogen-doped carbon nanomaterials as non-metal electrocatalysts for water oxidation. Nat. Commun. 4, 2390 (2013). The first metal-free catalyst (nitrogen-doped carbon) that exhibited comparable activity for the OER to non-precious metal catalysts.

  4. 4.

    , , & A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions. Nat. Nanotechnol. 10, 444–452 (2015). The first metal-free ORR and OER bifunctional catalyst (nitrogen- and phosphorus-doped carbon foam) for high-performance rechargeable zinc–air battery.

  5. 5.

    et al. Toward design of synergistically active carbon-based catalysts for electrocatalytic hydrogen evolution. ACS Nano 8, 5290–5296 (2014).

  6. 6.

    et al. Metal-free efficient photocatalyst for stable visible water splitting via a two-electron pathway. Science 347, 970–974 (2015).

  7. 7.

    et al. Nitrogen-doped graphene foams as metal-free counter electrodes in high-performance dye-sensitized solar cells. Angew. Chem. Int. Ed. 51, 12124–12127 (2012). This work shows the use of metal-free carbon (nitrogen-doped graphene foam) to replace platinum in high-performance dye-sensitized solar cells.

  8. 8.

    et al. Renewable and metal-free carbon nanofibre catalysts for carbon dioxide reduction. Nat. Commun. 4, 2189 (2013). This paper describes a metal-free catalyst (carbon fibre) that exhibits negligible overpotential (0.17 V) for CO2 reduction.

  9. 9.

    et al. Vertically aligned carbon nanotube-sheathed carbon fibers as pristine microelectrodes for selective monitoring of ascorbate in vivo. Anal. Chem. 86, 3909–3914 (2014).

  10. 10.

    et al. Silicon carbide-derived carbon nanocomposite as a substitute for mercury in the catalytic hydrochlorination of acetylene. Nat. Commun. 5, 3688 (2014). This work shows the use of a metal-free catalyst (nitrogen-doped carbon) to catalyse acetylene hydrochlorination as a potential substitute for mercury.

  11. 11.

    et al. Nitrogen-doped sp2-hybridized carbon as a superior catalyst for selective oxidation. Angew. Chem. Int. Ed. 52, 2109–2113 (2013).

  12. 12.

    , , , , & N,P-codoped carbon networks as efficient metal-free bifunctional catalysts for oxygen reduction and hydrogen evolution reactions. Angew. Chem. Int. Ed. 55, 2230–2234 (2016).

  13. 13.

    , , , & Metal-free catalysts for oxygen reduction reaction. Chem. Rev. 115, 4823–4892 (2015).

  14. 14.

    , , & Nitrogen-doped graphene as efficient metal-free electrocatalyst for oxygen reduction in fuel cells. ACS Nano 4, 1321–1326 (2010).

  15. 15.

    et al. Boron-doped carbon nanotubes as metal-free electrocatalysts for the oxygen reduction reaction. Angew. Chem. Int. Ed. 50, 7132–7135 (2011). The first carbon-based metal-free catalyst with an electron-deficient dopant (boron-doped CNT).

  16. 16.

    et al. Edge-selectively sulfurized graphene nanoplatelets as efficient metal-free electrocatalysts for oxygen reduction reaction: the electron spin effect. Adv. Mater. 25, 6138–6145 (2013).

  17. 17.

    , , , , & Phosphorus-doped graphite layers with high electrocatalytic activity for the O2 reduction in an alkaline medium. Angew. Chem. Int. Ed. 50, 3257–3261 (2011).

  18. 18.

    , , , , & Catalyst-free synthesis of iodine-doped graphene via a facile thermal annealing process and its use for electrocatalytic oxygen reduction in an alkaline medium. Chem. Comm. 48, 1027–1029 (2012).

  19. 19.

    et al. Facile, scalable synthesis of edge-halogenated graphene nanoplatelets as efficient metal-free eletrocatalysts for oxygen reduction reaction. Sci. Rep. 3, 1810 (2013).

  20. 20.

    , , , , & Vertically aligned BCN nanotubes as efficient metal-free electrocatalysts for the oxygen reduction reaction: a synergetic effect by co-doping with boron and nitrogen. Angew. Chem. Int. Ed. 50, 11756–11760 (2011). The first paper to show the co-doping effect to enhance the metal-free catalytic activities of carbon-based catalysts.

  21. 21.

    et al. BCN graphene as efficient metal-free electrocatalyst for the oxygen reduction reaction. Angew. Chem. Int. Ed. 51, 4209–4212 (2012).

  22. 22.

    et al. Can boron and nitrogen co-doping improve oxygen reduction reaction activity of carbon nanotubes? J. Am. Chem. Soc. 135, 1201–1204 (2013).

  23. 23.

    & & Vertically aligned carbon nanotube arrays co-doped with phosphorus and nitrogen as efficient metal-free electrocatalysts for oxygen reduction. J. Phys. Chem. Lett. 3, 2863–2870 (2012).

  24. 24.

    et al. Sulfur and nitrogen co-doped carbon nanotubes for enhancing electrochemical oxygen reduction activity in acidic and alkaline media. J. Mater. Chem. A 1, 14853–14857 (2013).

  25. 25.

    , , & Nitrogen-doped ordered mesoporous graphitic arrays with high electrocatalytic activity for oxygen reduction. Angew. Chem. Int. Ed. 49, 2565–2569 (2010).

  26. 26.

    et al. Phosphorus-doped graphite layers with high electrocatalytic activity for the O2 reduction in an alkaline Medium. Angew. Chem. Int. Ed. 50, 3257–3261 (2011).

  27. 27.

    et al. Chemically converted graphene as substrate for immobilizing and enhancing the activity of a polymer catalyst. Chem. Commun. 46, 4740–4742 (2010).

  28. 28.

    et al. Nanoporous graphitic-C3N4@carbon metal-free electrocatalysts for highly efficient oxygen reduction. J. Am. Chem. Soc. 133, 20116–20119 (2011).

  29. 29.

    , , , & Polyelectrolyte-functionalized graphene as metal-free electrocatalysts for oxygen reduction. ACS Nano 5, 6202–6209 (2011).

  30. 30.

    , & Polyelectrolyte functionalized carbon nanotubes as efficient metal-free electrocatalysts for oxygen reduction. J. Am. Chem. Soc. 133, 5182–5185 (2011).

  31. 31.

    et al. Significant contribution of intrinsic carbon defects to oxygen reduction activity. ACS Catal. 5, 6707–6712 (2015). The first experimental and theoretical combined study on the ORR activities induced by intrinsic carbon defects.

  32. 32.

    et al. Graphene quantum dots supported by graphene nanoribbons with ultrahigh electrocatalytic performance for oxygen reduction. J. Am. Chem. Soc. 137, 7588–7591 (2015).

  33. 33.

    et al. Hydrogen evolution by a metal-free electrocatalyst. Nat. Commun. 5, 3783 (2014). The first metal-free catalyst (nitrogen-doped carbon) for the HER.

  34. 34.

    , , , & Oxygen evolution reaction electrocatalysis on transition metal oxides and (oxy)hydroxides: activity trends and design principles. Chem. Mater. 27, 7549–7558 (2015).

  35. 35.

    , & Electrocatalysis developments for hydrogen evolution reaction in alkaline solutions — A Review. Int. J. Hydrogen Energy 40, 256–274 (2015).

  36. 36.

    et al. The synthesis of nanostructured Ni5P4 films and their use as a non-noble bifunctional electrocatalyst for full water splitting. Angew. Chem. Int. Ed. 54, 12361–12365 (2015).

  37. 37.

    , , & Heteroatom-doped graphene-based materials for energy-relevant electrocatalytic processes. ACS Catal. 5, 5207–5234 (2015).

  38. 38.

    , , & Micelle-template synthesis of nitrogen-doped mesoporous graphene as an efficient metal-free electrocatalyst for hydrogen production. Sci. Rep. 4, 7557 (2014).

  39. 39.

    , , , & Simple preparation of nanoporous few-layer nitrogen-doped graphene for use as an efficient electrocatalyst for oxygen reduction and oxygen evolution reactions. Carbon 53, 130–136 (2013).

  40. 40.

    , & N-Doped graphene as a bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions in an alkaline electrolyte. Int. J. Hydrogen Energy 39, 15913–15919 (2014).

  41. 41.

    , & Metal-free B-doped graphene with efficient electrocatalytic activity for hydrogen evolution reaction. Catal. Sci. Technol. 4, 2023–2030 (2014).

  42. 42.

    et al. Acidically oxidized carbon cloth: a novel metal-free oxygen evolution electrode with high catalytic activity. Chem. Commun. 51, 1616–1619 (2015).

  43. 43.

    , , , & High catalytic activity of nitrogen and sulfur co-doped nanoporous graphene in the hydrogen evolution reaction. Angew. Chem. Int. Ed. 54, 2131–2136 (2015).

  44. 44.

    , , , & Nitrogen- and phosphorus-doped biocarbon with enhanced electrocatalytic activity for oxygen reduction. ACS Catal. 5, 920–927 (2015).

  45. 45.

    et al. Edge-carboxylated graphene nanosheets via ball milling. Proc. Natl Acad. Sci. USA 109, 5588–5593 (2012).

  46. 46.

    et al. Edge-carboxylated graphene nanoplatelets as oxygen-rich metal-free cathodes for organic dye-sensitized solar cells. Energy Environ. Sci. 7, 1044–1052 (2014).

  47. 47.

    , , & On the role of metals in nitrogen-doped carbon electrocatalysts for oxygen reduction. Angew. Chem. Int. Ed. 54, 10102–10120 (2015).

  48. 48.

    et al. Oxygen reduction reaction in a droplet on graphite: direct evidence that the edge is more active than the basal plane. Angew. Chem. Int. Ed. 53, 10804–10808 (2014).

  49. 49.

    et al. Metal-free heterogeneous catalysis for sustainable chemistry. ChemSusChem. 3, 169–180 (2010).

  50. 50.

    et al. Exploration of the active center structure of nitrogen-doped graphene-based catalysts for oxygen reduction reaction. Energy Environ. Sci. 5, 7936–7942 (2012).

  51. 51.

    & Mechanisms of oxygen reduction reaction on nitrogen-doped graphene for fuel cells. Langmuir 115 11170–11176 (2011). The first paper to show the doping-induced spin redistribution as the driving force for metal-free catalytic activities of carbon-based catalysts.

  52. 52.

    , , , & Oxygen reduction reaction mechanism on nitrogen-doped graphene: a density functional theory study. J. Catal. 282, 183–190 (2011).

  53. 53.

    et al. Trace metal residues promote the activity of supposedly metal-free nitrogen-modified carbon catalysts for the oxygen reduction reaction. Electrochem. Commun. 34, 113–116 (2013).

  54. 54.

    & Heteroatom-doped graphitic carbon catalysts for efficient electrocatalysis of oxygen reduction reaction. ACS Catal. 5, 7244–7253 (2015).

  55. 55.

    et al. Active sites of nitrogen-doped carbon materials for oxygen reduction reaction clarified using model catalysts. Science 351, 361–365 (2016). Detailed experimental elucidation of the ORR mechanism by metal-free nitrogen-doped carbon catalysts.

  56. 56.

    , & Polyelectrolyte functionalized carbon nanotubes as efficient metal-free electrocatalysts for oxygen reduction. J. Am. Chem. Soc. 133, 5182–5185 (2011).

  57. 57.

    , , & Modeling the oxygen evolution reaction on metal oxides: the infuence of unrestricted DFT calculations. J. Phys. Chem. C 118, 4095–4102 (2014).

  58. 58.

    , , , & N-Doped graphene as catalysts for oxygen reduction and oxygen evolution reactions: theoretical considerations. J. Catal. 314, 66–72 (2014).

  59. 59.

    , , & Electrocatalytic oxygen evolution at surface-oxidized multiwall carbon nanotubes. J. Am. Chem. Soc. 137, 2901–2907 (2015).

  60. 60.

    , , & Advancing the electrochemistry of the hydrogen-evolution reaction through combining experiment and theory. Angew. Chem. Int. Ed. 54, 52–65 (2015).

  61. 61.

    et al. Polyethylenimine-enhanced electrocatalytic reduction of CO2 to formate at nitrogen-doped carbon nanomaterials. J. Am. Chem. Soc. 136, 7845–7848 (2014).

  62. 62.

    et al. Achieving highly efficient, selective, and stable CO2 reduction on nitrogen-doped carbon nanotubes. ACS Nano 9, 5364–5371 (2015).

  63. 63.

    & Doping carbons beyond nitrogen: an overview of advanced heteroatom doped carbons with boron, sulphur and phosphorus for energy applications. Energy Environ. Sci. 6, 2839–2855 (2013).

  64. 64.

    , , , , & Nitrogen-doped holey graphitic carbon from 2D covalent organic polymers for oxygen reduction. Adv. Mater. 26, 3315–3320 (2014).

  65. 65.

    , , & Preparation of nitrogen-doped carbon nanotube arrays and their catalysis towards cathodic oxygen reduction in acidic and alkaline media. Carbon 50, 2620–2627 (2012).

  66. 66.

    et al. Toward full exposure of “active sites”: nanocarbon electrocatalyst with surface enriched nitrogen for superior oxygen reduction and evolution reactivity. Adv. Funct. Mater. 24, 5956–5961 (2014).

  67. 67.

    , , & Prediction of 3D elastic moduli and Poisson's ratios of pillared graphene nanostructres. Carbon 50, 603–611 (2012).

  68. 68.

    et al. Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage. Nat. Nanotechnol. 9, 555–562 (2014).

  69. 69.

    , , , , & Preparation of tunable 3D pillared carbon nanotube–graphene networks for high-performance capacitance. Chem. Mater. 23, 4810–4816 (2011).

  70. 70.

    et al. Rationally designed graphene-nanotube 3D architectures with a seamless nodal junction for efficient energy conversion and storage. Sci. Adv. 1, e1400198 (2015).

  71. 71.

    et al. Nitrogen-doped carbon nanocages as efficient metal-free electrocatalysts for oxygen reduction reaction. Adv. Mater. 24, 5593–5597 (2012).

  72. 72.

    , , & Graphitic carbon nitride nanosheet–carbon nanotube three-dimensional porous composites as high-performance oxygen evolution electrocatalysts. Angew. Chem. Int. Ed. 53, 7281–7285 (2014).

  73. 73.

    , , & Paper-based N-doped carbon films for enhanced oxygen evolution electrocatalysis. Adv. Sci. 2, 1–2 (2015).

  74. 74.

    , , , & Nitrogen and sulfur codoped graphite foam as a self-supported metal-free electrocatalytic electrode for water oxidation. Adv. Energy Mater. 6, 1501492 (2016).

  75. 75.

    et al. Acidically oxidized carbon cloth: a novel metal-free oxygen evolution electrode with high catalytic activity. Chem. Commun. 51, 1616–1619 (2015).

  76. 76.

    , , & Electrocatalytic oxygen evolution at surface-oxidized multiwall carbon nanotubes. J. Am. Chem. Soc. 137, 2901–2907 (2015).

  77. 77.

    , , , & Vertically aligned N-doped coral-like carbon fiber arrays as efficient air electrodes for high-performance nonaqueous Li–O2 batteries. ACS Nano 8, 3015–3022 (2014).

  78. 78.

    et al. Metal-free activation of H2O2 by g-C3N4 under visible light irradiation for the degradation of organic pollutants. Phys. Chem. Chem. Phys. 14, 1455–1462 (2012).

  79. 79.

    et al. Platinized aligned carbon nanotube-sheathed carbon fiber microelectrodes for in vivo amperometric monitoring of oxygen. Anal. Chem. 86, 5017–5023 (2014).

  80. 80.

    , & Future CO2 emissions and climate change from existing energy infrastructure. Science 329, 1330–1333 (2010).

  81. 81.

    et al. Incorporation of nitrogen defects for efficient reduction of CO2 via two-electron pathway on three-dimensional graphene foam. Nano Lett. 16, 466–470 (2016).

  82. 82.

    et al. Nitrogen-doped carbon nanotube arrays for high-efficiency electrochemical reduction of CO2: on the understanding of defects, defect density, and selectivity. Angew. Chem. Int. Ed. 54, 13701–13705 (2015).

  83. 83.

    , , , & Carbon-catalysed reductive hydrogen atom transfer reactions. Nat. Commun. 6, 6478 (2015).

  84. 84.

    & Metal-free carbon catalysts for oxidative dehydrogenation reactions. ACS Catal. 4, 3212–3218 (2014).

  85. 85.

    et al. Nitrogen-doped graphene nanosheets as metal-free catalysts for aerobic selective oxidation of benzylic alcohols. ACS Catal. 2, 622–631 (2012).

  86. 86.

    et al. P-Doped porous carbon as metal free catalysts for selective aerobic oxidation with an unexpected mechanism. ACS Nano 10, 2305–2315 (2016).

  87. 87.

    et al. Confining noble metal (Pd, Au, Pt) nanoparticles in surfactant ionic liquids: active non-mercury catalysts for hydrochlorination of acetylene. ACS Catal. 5, 6724–6731(2015).

Download references

Acknowledgements

The authors thank colleagues, collaborators and peers whose work was cited in this article, and are also grateful for the financial support from NSF, NSF-NSFC, AFOSR-DoD-MURI, DAGSI, CWRU, The 111 Project (B14004), The State Key Laboratory of Organic-Inorganic Composites, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, and BUCT.

Author information

Affiliations

  1. BUCT-CWRU International Joint Laboratory, State Key Laboratory of Organic-Inorganic Composites, Center for Soft Matter Science and Engineering, College of Energy, Beijing University of Chemical Technology, Beijing 100029, China.

    • Xien Liu
    •  & Liming Dai
  2. Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.

    • Liming Dai

Authors

  1. Search for Xien Liu in:

  2. Search for Liming Dai in:

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Liming Dai.

About this article

Publication history

Published

DOI

https://doi.org/10.1038/natrevmats.2016.64