Article | Open | Published:

Nitrogen-doped mesoporous SiC materials with catalytically active cobalt nanoparticles for the efficient and selective hydrogenation of nitroarenes

Scientific Reportsvolume 8, Article number: 2567 (2018) | Download Citation


Mesoporous nitrogen-doped silicon carbide catalysts with integrated cobalt nanoparticles (Co@N-SiC) were synthesized by the thermal decomposition of a microphase-separated block copolymer of polycarbosilane and polyethylene. The catalysts are highly active, reusable and offer selective hydrogenation of the nitro group in the presence of hydrogenation-sensitive functional groups.


Intensive efforts have been devoted recently to designing novel catalysts with enhanced catalytic properties utilizing earth-abundant transition metals1,2,3. Cobalt, among other metals, has attracted many researchers and numerous homogeneous4,5,6 and heterogeneous cobalt catalysts7,8,9,10,11,12,13,14,15,16,17,18 have been developed for various catalytic transformations. Beller and co-workers19, for instance, developed a cobalt-oxide@N-carbon catalyst by the thermal decomposition of a specific cobalt complex for the selective hydrogenation of nitroarenes. This is an industrially important reaction, as aniline and its derivatives find applications in the synthesis of pharmaceutical, dyes, polymers, agrichemicals and other fine chemicals20,21. Moreover reduction of nitroarenes has served as a benchmark reaction to test the activity of nanoparticles (NPs)22. Thus, the development of new catalysts with important features, such as economy, activity, selectivity and reusability, is highly relevant23. In the past various catalysts based on Au24, Ag25, Ni26, Fe27 and Cu28 has been designed for the reduction of nitroarenes. Since the pioneer work of Beller, a variety of Co and especially Co@N-carbon catalysts have been developed29,30,31,32,33,34,35,36,37,38,39,40,41,42,43. Recent studies have shown that the stability of Co-N-C bond plays a vital role in the temperature-dependent formation of cobalt single atoms to NPs44. N-functions of the support are crucial not only for the stabilization of metal NPs, but also for the dispersion of the catalyst in polar solvents used for the catalysis45. Moreover, an increase in the activity with an increase in nitrogen content of the catalyst was observed46. Silicon carbide (SiC) and silicon carbonitride (SiCN), being refractory materials, could extend the application profile of cobalt-based solid catalysts if used as a catalyst support. We have demonstrated the catalytic potential of metal@SiCN materials for various transformations47,48,49,50,51,52,53,54, including a cobalt-based catalyst for the reduction of nitroarenes and the direct synthesis of imines and benzimidazoles from nitroarenes and aldehydes55. In addition, we introduced an approach for the one-step synthesis of porous SiC materials56.

Here, we report the development of a N-doped mesoporous SiC cobalt nanocomposite material (Co@N-SiC) which affords remarkable activity, selectivity and reuse in the hydrogenation of nitroarenes.

Results and Discussions

The synthesis of Co@N-SiC is summarized in Fig. 1, while details are provided in the supporting information (SI). A commercial polycarbosilane (PCS) was reacted with a hydroxyl-terminated polyethylene (PEOH)57 to synthesize a PCS-block-PE (PCS-b-PE) polymer via dehydrocoupling of Si-H and O-H bonds56. A cobalt complex ([Co(phen)2](OAc)2 where phen: phenanthroline and OAc: acetate) was added to this block copolymer and the melt was slowly cooled to room temperature to achieve nanostructuring. The PEOH and the cobalt complex decompose upon pyrolysis (under nitrogen) (see TGA in Figure S1), leaving behind an amorphous SiC material with integrated cobalt NPs. The formation of SiC ceramics was confirmed by FT-IR analysis (see Fig. S2 in SI). The absence of characteristic bands at 2852 and 2926 cm−1 (C-H stretching vibration) and those at 2200 cm−1 (Si-H) confirmed the removal of the organic block and the formation of SiC material.

Co@N-SiC was investigated by transmission electron microscopy. A piece of the catalyst, as shown in Fig. 2a, indicates a structured, but not highly ordered material. A magnified view of the region selected (red square in Fig. 2a) shows metallic NPs (Fig. 2b) with an average size of 5 nm. Elemental composition of the material was investigated by energy-dispersive X-ray analysis and the results are presented in Fig. 2c. Characteristic peaks corresponding to cobalt can be seen along with those of carbon and some oxygen. The formation of graphitic carbon, as reported earlier56, is likely from the decomposition of the organic block. A small amount of oxygen could arise from the PEOH block. Presence of nitrogen (2.5 wt%) in Co@N-SiC material was confirmed through elemental analysis, which is an indication that nitrogen has been successfully incorporated in the material. It would be worth mentioning at this stage that pyrolysis of PCS only provides a non-porous SiC material with no nitrogen doping.

Figure 1
Figure 1

Synthesis of mesoporous Co@N-SiC ceramics; (I) block copolymer formation; (II) microphase separation; (III) metallation with a Co complex [Co(L2)(OAC)2] where L: phenanthroline, OAc: acetate; (IV) pyrolysis.

Figure 2
Figure 2

Transmission electron microscopy images of Co@N-SiC catalysts (a and b), magnified view of selected area from (a) is shown in (b), where the inset shows the size distribution of Co NPs (encircled). The EDX of the catalyst is presented in (c). Reusability of the catalyst is presented in (d).

The presence of permanent porosity in the material was confirmed by nitrogen physisorption. The catalyst showed a high specific surface area (400 m2/g) and rather widely distributed mesopores (about 4–15 nm, see Fig. 3b). A hysteresis and closure of the loop near 0.4 P/P0 is typical of mesoporous materials in an adsorption-desorption isotherm (Fig. 3a). Although t-plot method58 suggested almost no contribution of micropores to the total surface area, the presence of micropores, however could not be ruled out completely because of the significant adsorption of nitrogen at relative pressure values <0.05.

Figure 3
Figure 3

Nitrogen adsorption-desorption isotherm (a) and pore size distribution (b) of synthesized catalyst.

Catalytic activity of the material for the hydrogenation of nitroarenes with molecular hydrogen was investigated without using any catalyst promoter or a base. Firstly, nitrobenzene was used as a substrate and the effect of various parameters, for example, solvent, temperature, reaction time and catalyst loading, was investigated. The highest yield of aniline (90%) during solvent screening (Table T1 in SI) was obtained in water (entry 1) and water ethanol mixture (entry 2), whereas THF was found to be the least effective (entry 3). However, activity of the catalyst decreased in pure ethanol and only 42% of nitrobenzene was hydrogenated under screening conditions. Although the highest activity of the catalyst was found in water, a mixture of ethanol and water was used for further studies due to the insolubility of many of the tested compounds in pure water. The other reaction parameters, such as temperature, time and hydrogen pressure, were also varied and optimized. A complete conversion of nitrobenzene to aniline was achieved under optimized reaction conditions [0.5 mmol nitrobenzene, 90 °C, 4.0 MPa H2, 0.5 mol% catalyst metal, 4 mL solvent (EtOH and water 1:1), 20 h]. We tried different ligands (Table T2 in SI) for the synthesis of the Co@N-SiC catalysts and only the complex with phen ligand (entry 3) showed catalytic activity. This observation could be attributed to the ability of phen ligand to retain higher nitrogen content in the catalyst as compared to other ligands tested46,59. The catalyst can be used in several successive runs without losing any activity, as can be seen in Fig. 2d. From this, it can be concluded that the cobalt particles are well embedded in the support and that N-functions of the support may play a crucial role regarding the strong catalyst support interactions. A small reduction in catalytic activity was noted only in the fourth cycle, which falls under the GC error. In the last step, selective hydrogenation of the nitro group in the presence of other functional groups was studied and the results are presented in Table 1. Selective hydrogenation of the nitro group without any dehalogenation was observed in the case of nitroarenes with chloro (entries 2–4), bromo (entries 5–7), fluoro (entry 9) and iodo (entry 8) groups. C-C double bond (entry 14), carbonyl group (entry 13) and nitrile (entry 10) functional groups, usually highly sensitive towards hydrogenation, were also not hydrogenated. Sterically demanding arenes, such as 5-nitroisoquinoline (entry 17), were also converted in high yields. The yields were above 95% for all reactions, except for the substrates with sterically demanding substituents, such as bromine (entry 5), phenyl (entry 16), amine (entry 18) or primary alcohol (entry 11) at the ortho position. A dinitro compound was also hydrogenated upon doubling of the catalyst amount (entry 15).

Table 1 Hydrogenation of various nitroarenes using the Co@N-SiC catalyst[a].


One-pot synthesis of a nitrogen-doped SiC material containing cobalt NPs (Co@N-SiC) is feasible via the formation, microphase separation and pyrolysis of a polycarbosilane-block-polyethylene polymer modified with a cobalt phenanthroline complex. The porous nanocomposite catalysts subsequently obtained show a high surface area and large mesopores. The Co@N-SiC materials are active, robust, selective and reusable in the hydrogenation of nitroarenes to anilines. Selective hydrogenation of the nitro group in the presence of functional groups sensitive towards hydrogenation, such as the C-C double bond, carbonyl moiety, iodo and nitrile groups, was achieved successfully. We expect that the catalyst synthesis protocol introduced here can be used for the synthesis of a variety of highly active and reusable base metal catalysts.


Synthesis of Co@N-SiC

OH-terminated polyethylene (Mn = 1194 g/mol, Mw = 1506 g/mol, PDI = 1.26) was first dissolved in pyridine followed by the addition of PCS in the weight ratio of 30/70 (PE-OH:PCS). Dehydrocoupling of the Si-H and O-H groups leads to the formation of a block copolymer (PCS-b-PE) in which both organic (PE) and inorganic (PCS) blocks are covalentally bonded. As both blocks are immiscible and covalentally bonded, microphase separation leads to the formation of a nanostructured material. Afterwards cobalt complex [Co(phen)2](OAc)2 was added to achieve a metal to silicon ratio of 1 to 20 (3 wt% Co). The cross-linking of PCS block was started by the addition of dicumyl peroxide (5 wt% with respect to PCS). Preceramic cross-linked material is called a “greenbody”.

Green body was pyrolysed at 750 °C with a heating rate of 1 K/min up to 300 °C and afterwards 5 K/min up to final temperature. The material was held for two hours each at 300, 400 and 500 °C.


In a typical catalysis run, nitroarene (0.5 mmol), solvent (4 mL) and catalyst (0.5–2 mol%) were charged in a Parr autoclave and reactor was pressurized with hydrogen (4.0 MPa). The autoclave was heated with stirring to a specified temperature and cooled to room temperature at the end of the reaction. The catalyst was separated by centrifugation and products were extracted in diethyl ether and quantified using GC.

Additional information

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Roger, I., Shipman, M. A. & Symes, M. D. Earth-abundant catalysts for electrochemical and photoelectrochemical water splitting. Nature Reviews Chemistry 1, 0003, (2017).

  2. 2.

    Chirik, P. & Morris, R. Getting Down to Earth: The Renaissance of Catalysis with Abundant Metals. Accounts of Chemical Research 48, 2495–2495, (2015).

  3. 3.

    Wang, D. & Astruc, D. The recent development of efficient Earth-abundant transition-metal nanocatalysts. Chemical Society Reviews 46, 816–854, (2017).

  4. 4.

    Korstanje, T. J., I van der Vlugt, J., Elsevier, C. J. & de Bruin, B. Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst. Science 350, 298–302, (2015).

  5. 5.

    Renaud, J.-L. & Gaillard, S. Recent Advances in Iron- and Cobalt-Complex-Catalyzed Tandem/Consecutive Processes Involving Hydrogenation. Synthesis 48, 3659–3683, (2016).

  6. 6.

    Chirik, P. J. Iron- and Cobalt-Catalyzed Alkene Hydrogenation: Catalysis with Both Redox-Active and Strong Field Ligands. Acc. Chem. Res. 48, 1687–1695, (2015).

  7. 7.

    Chen, B., Li, F., Huang, Z. & Yuan, G. Recyclable and Selective Nitroarene Hydrogenation Catalysts Based on Carbon-Coated Cobalt Oxide Nanoparticles. ChemCatChem 8, 1132–1138, (2016).

  8. 8.

    Chen, F. et al. Selective Catalytic Hydrogenation of Heteroarenes with N-Graphene-Modified Cobalt Nanoparticles (Co3O4-Co/NGr@alpha-Al2O3). J. Am. Chem. Soc. 137, 11718–11724, (2015).

  9. 9.

    Chen, F. et al. Stable and Inert Cobalt Catalysts for Highly Selective and Practical Hydrogenation of C=N and C-O Bonds. J. Am. Chem. Soc. 138, 8781–8788, (2016).

  10. 10.

    Iosub, A. V. & Stahl, S. S. Catalytic Aerobic Dehydrogenation of Nitrogen Heterocycles Using Heterogeneous Cobalt Oxide Supported on Nitrogen-Doped Carbon. Org. Lett. 17, 4404–4407, (2015).

  11. 11.

    Jagadeesh, R. V. et al. Highly selective transfer hydrogenation of functionalised nitroarenes using cobalt-based nanocatalysts. Green Chem. 17, 898–902, (2015).

  12. 12.

    Mao, F. et al. Heterogeneous cobalt catalysts for selective oxygenation of alcohols to aldehydes, esters and nitriles. RSC Adv. 7, 1498–1503, (2017).

  13. 13.

    Shimizu, K.-i et al. Heterogeneous cobalt catalysts for the acceptorless dehydrogenation of alcohols. Green Chem. 15, 418–424, (2013).

  14. 14.

    Yang, C., Fu, L., Zhu, R. & Liu, Z. Influence of cobalt species on the catalytic performance of Co-N-C/SiO2 for ethylbenzene oxidation. Phys. Chem. Chem. Phys. 18, 4635–4642, (2016).

  15. 15.

    Zhao, T.-J. et al. General transfer hydrogenation by activating ammonia-borane over cobalt nanoparticles. RSC Adv. 5, 102736–102740, (2015).

  16. 16.

    Zhou, H. et al. Cobalt catalysts: very efficient for hydrogenation of biomass-derived ethyl levulinate to gamma-valerolactone under mild conditions. Green Chem. 16, 3870–3875, (2014).

  17. 17.

    Wang, J. et al. Recent Progress in Cobalt-Based Heterogeneous Catalysts for Electrochemical Water Splitting. Adv. Mater. 28, 215–230, (2016).

  18. 18.

    Jagadeesh, R. V. et al. Cobalt-based nanocatalysts for green oxidation and hydrogenation processes. Nat. protoc. 10, 916–926, (2015).

  19. 19.

    Westerhaus, F. A. et al. Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes. Nat. Chem. 5, 537–543, (2013).

  20. 20.

    Downing, R. S., Kunkeler, P. J. & van Bekkum, H. Catalytic syntheses of aromatic amines. Catal. Today 37, 121–136, (1997).

  21. 21.

    Blaser, H.-U., Steiner, H. & Studer, M. Selective Catalytic Hydrogenation of Functionalized Nitroarenes: An Update. ChemCatChem 1, 210–221, (2009).

  22. 22.

    Aditya, T., Pal, A. & Pal, T. Nitroarene reduction: a trusted model reaction to test nanoparticle catalysts. Chem. Commun. 51(46), 9410–9431 (2015).

  23. 23.

    Kadam, H. K. & Tilve, S. G. Advancement in methodologies for reduction of nitroarenes. RSC Adv. 5, 83391–83407, (2015).

  24. 24.

    Corma, A. & Serna, P. Chemoselective Hydrogenation of Nitro Compounds with Supported Gold Catalysts. Science 313(5785), 332–334 (2006).

  25. 25.

    Salam, N. et al. Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcohols. Appl. Catal. A: Gen. 477, 184–194 (2014).

  26. 26.

    Wang, J., Yuan, Z., Nie, R., Hou, Z. & Zheng, X. Hydrogenation of Nitrobenzene to Aniline over Silica Gel Supported Nickel Catalysts. Ind. Eng. Chem. Res. 49(10), 4664–4669 (2010).

  27. 27.

    Jagadeesh, R. V. et al. Nanoscale Fe2O3-Based Catalysts for Selective Hydrogenation of Nitroarenes to Anilines. Science 342(6162), 1073–1076 (2013).

  28. 28.

    Patra, A. K., Dutta, A. & Bhaumik, A. Cu nanorods and nanospheres and their excellent catalytic activity in chemoselective reduction of nitrobenzenes. Catal. Commun. 11(7), 651–655 (2010).

  29. 29.

    Wang, X. & Li, Y. Chemoselective hydrogenation of functionalized nitroarenes using MOF-derived co-based catalysts. J. Mol. Catal. A: Chem. 420, 56–65, (2016).

  30. 30.

    Sun, X. et al. Metal–Organic Framework Mediated Cobalt/Nitrogen-Doped Carbon Hybrids as Efficient and Chemoselective Catalysts for the Hydrogenation of Nitroarenes. ChemCatChem 9, 1854–1862, (2017).

  31. 31.

    Liu, L., Concepción, P. & Corma, A. Non-noble metal catalysts for hydrogenation: A facile method for preparing Co nanoparticles covered with thin layered carbon. J. Catal. 340, 1–9, (2016).

  32. 32.

    Chen, F. et al. Selective Semihydrogenation of Alkynes with N-Graphitic-Modified Cobalt Nanoparticles Supported on Silica. ACS Catal. 7, 1526–1532, (2017).

  33. 33.

    Long, J., Zhou, Y. & Li, Y. Transfer hydrogenation of unsaturated bonds in the absence of base additives catalyzed by a cobalt-based heterogeneous catalyst. Chem. Commun. 51, 2331–2334, (2015).

  34. 34.

    Sorribes, I., Liu, L. & Corma, A. Nanolayered Co–Mo–S Catalysts for the Chemoselective Hydrogenation of Nitroarenes. ACS Catal. 7, 2698–2708, (2017).

  35. 35.

    Wei, Z. et al. In Situ-Generated Co0-Co3O4/N-Doped Carbon Nanotubes Hybrids as Efficient and Chemoselective Catalysts for Hydrogenation of Nitroarenes. ACS Catal. 5, 4783–4789, (2015).

  36. 36.

    Ji, P. et al. Single-Site Cobalt Catalysts at New Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6 Metal–Organic Framework Nodes for Highly Active Hydrogenation of Nitroarenes, Nitriles, and Isocyanides. J. Am. Chem. Soc. 139, 7004–7011, (2017).

  37. 37.

    Zhang, F. et al. In situ mosaic strategy generated Co-based N-doped mesoporous carbon for highly selective hydrogenation of nitroaromatics. J. Catal. 348, 212–222, (2017).

  38. 38.

    Zhou, P. & Zhang, Z. One-pot Reductive Amination of carbonyl Compounds with Nitro Compounds by Transfer Hydrogenation over Co–Nx as catalyst. ChemSusChem 10, 1892–1897, (2017).

  39. 39.

    Alex, H. et al. Polymer Encapsulated Cobalt-Based Catalysts (Co EnCatTM) for Selective Continuous Hydrogenation of 1-Iodo-4-nitrobenzene. ChemCatChem 9, 3210–3217, (2017).

  40. 40.

    Pedrajas, E. et al. Efficient and Selective N-Methylation of Nitroarenes under Mild Reaction Conditions. Chem. Eur. J. 23, 13205–13212, (2017).

  41. 41.

    Cui, X. et al. Cobalt nanoparticles supported on N-doped mesoporous carbon as a highly efficient catalyst for the synthesis of aromatic amines. J. Colloid interface Sci. 501, 231–240, (2017).

  42. 42.

    Sahoo, B. et al. Biomass-Derived Catalysts for Selective Hydrogenation of Nitroarenes. ChemSusChem 10, 3035–3039, (2017).

  43. 43.

    Liu, L., Gao, F., Concepción, P. & Corma, A. A new strategy to transform mono and bimetallic non-noble metal nanoparticles into highly active and chemoselective hydrogenation catalysts. J. Catal. 350, 218–225, (2017).

  44. 44.

    Nakatsuka, K., Yoshii, T., Kuwahara, Y., Mori, K. & Yamashita, H. Controlled synthesis of carbon-supported Co catalysts from single-sites to nanoparticles: characterization of the structural transformation and investigation of their oxidation catalysis. Phys. Chem. Chem. Phys. 19, 4967–4974, (2017).

  45. 45.

    Zaheer, M., Schmalz, T., Motz, G. & Kempe, R. Polymer derived non-oxide ceramics modified with late transition metals. Chem. Soc. Rev. 41, 5102–5116, (2012).

  46. 46.

    Formenti, D. et al. Co-based heterogeneous catalysts from well-defined α-diimine complexes: Discussing the role of nitrogen. J. Catal. 351, 79–89, (2017).

  47. 47.

    Fehn, S., Zaheer, M., Denner, C. E., Friedrich, M. & Kempe, R. Robustly supported rhodium nanoclusters: synthesis and application in selective hydrogenation of lignin derived phenolic compounds. New J. Chem. 40, 9252–9256, (2016).

  48. 48.

    Forberg, D. et al. The synthesis of pyrroles via acceptorless dehydrogenative condensation of secondary alcohols and 1,2-amino alcohols mediated by a robust and reusable catalyst based on nanometer-sized iridium particles. Catal. Sci. Technol. 4, 4188–4192, (2014).

  49. 49.

    Forberg, D. et al. Single-catalyst high-weight% hydrogen storage in an N-heterocycle synthesized from lignin hydrogenolysis products and ammonia. Nat. Commun. 7, 13201, (2016).

  50. 50.

    Glatz, G. et al. Copper-Containing SiCN Precursor Ceramics (Cu@SiCN) as Selective Hydrocarbon Oxidation Catalysts Using Air as an Oxidant. Chem. Eur. J. 16, 4231–4238, (2010).

  51. 51.

    Hahn, G., Ewert, J.-K., Denner, C., Tilgner, D. & Kempe, R. A Reusable Mesoporous Nickel Nanocomposite Catalyst for the Selective Hydrogenation of Nitroarenes in the Presence of Sensitive Functional Groups. ChemCatChem 8, 2461–2465, (2016).

  52. 52.

    Zaheer, M. et al. Robust Microporous Monoliths with Integrated Catalytically Active Metal Sites Investigated by Hyperpolarized 129Xe NMR. Chem. Mater. 24, 3952–3963, (2012).

  53. 53.

    Zaheer, M., Motz, G. & Kempe, R. The generation of palladium silicide nanoalloy particles in a SiCN matrix and their catalytic applications. J. Mater. Chem. 21, 18825–18831, (2011).

  54. 54.

    Sachau, S. M. et al. Micro-/Mesoporous Platinum–SiCN NanocompositeCatalysts (Pt@SiCN): From Design to Catalytic Applications. Chem. Eur. J. 22, 15508–15512, (2016).

  55. 55.

    Schwob, T. & Kempe, R. A Reusable Co Catalyst for the Selective Hydrogenation of Functionalized Nitroarenes and the Direct Synthesis of Imines and Benzimidazoles from Nitroarenes and Aldehydes. Angew. Chem. Int. Ed. 55, 15175–15179, (2016).

  56. 56.

    Zaheer, M., Hermannsdörfer, J., Kretschmer, W. P., Motz, G. & Kempe, R. Robust Heterogeneous Nickel Catalysts with Tailored Porosity for the Selective Hydrogenolysis of Aryl Ethers. ChemCatChem 6, 91–95, (2014).

  57. 57.

    Pillai, S. K. T., Kretschmer, W. P., Trebbin, M., Förster, S. & Kempe, R. Tailored Nanostructuring of End-Group-Functionalized High-Density Polyethylene Synthesized by an Efficient Catalytic Version of Ziegler’s “Aufbaureaktion”. Chem. Eur. J. 18, 13974–13978, (2012).

  58. 58.

    Lippens, B. C. & de Boer, J. H. Studies on pore systems in catalysts: V. The t method. J. Catal. 4, 319–323, (1965).

  59. 59.

    He, L., Weniger, F., Neumann, H. & Beller, M. Synthesis, Characterization, and Application of Metal Nanoparticles Supported on Nitrogen-Doped Carbon: Catalysis beyond Electrochemistry. Angew. Chem. Int. Ed. 55, 12582–94, (2016).

Download references


M.Z. thanks HEC Pakistan for financial assistance under NRPU (Project 4131). R.K. thanks the DFG KE 756/29-1 for financial support. DFG and University of Bayreuth are also acknowledged for their support under “open access publishing” program.

Author information


  1. Lehrstuhl fuer Anorganische Chemie II-Katalysatordesign, Universitaet Bayreth, Universitaetstr, 30, 95447, Bayreuth, Germany

    • Mirco Eckardt
    •  & Rhett Kempe
  2. Department of Chemistry and Chemical Engineering, SBA School of Science and Engineering, Lahore University of Management Sciences (LUMS), 54792, Lahore, Pakistan

    • Muhammad Zaheer


  1. Search for Mirco Eckardt in:

  2. Search for Muhammad Zaheer in:

  3. Search for Rhett Kempe in:


The idea was conceived by R.K. who was also involved in the writing and editing of the manuscript. M.E. performed all the experiments while M.Z. wrote the manuscript.

Competing Interests

The authors declare no competing interests.

Corresponding authors

Correspondence to Muhammad Zaheer or Rhett Kempe.

Electronic supplementary material

About this article

Publication history






By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.