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Dalton Transactions
Page 5 of 6
DOI: 10.1039/C8DT00302E
Journal Name
ARTICLE
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M. G. Walter, E. L. Warren, J. R. McKone, S. W. Boettcher, Q. Mi,
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H. B. Gray, Nat. Chem., 2009, 1, 7–7.
N. S. Lewis and D. G. Nocera, Proc. Natl. Acad. Sci., 2006, 103,
correspond to faster kinetics, this result indicates that
better electrocatalyst than 2.
1 is a
2
3
4
The amount of H2 gas evolved was quantified using a gas
chromatograph (GC) after performing bulk electrolysis for an
hour. Figure 4b presents the passed charge after an hour’s
constant electrolysis. The amount of generated H2 is consistent
with the theoretical production based on Faraday’s law,
assuming all the charges were accounted for the 2 e‐ reduction
of proton to generate H2, implying quantitative faradaic yield.
Electrical impedance spectroscopy (EIS) was conducted to
understand the conductivity of the polymeric network. The
15729–15735.
5
6
7
8
9
C. G. Morales‐Guio, L.‐A. Stern and X. Hu, Chem. Soc. Rev., 2014,
43, 6555–6569.
M.‐R. Gao, J.‐X. Liang, Y.‐R. Zheng, Y.‐F. Xu, J. Jiang, Q. Gao, J. Li
and S.‐H. Yu, Nat. Commun., , DOI:10.1038/ncomms6982.
J. R. McKone, B. F. Sadtler, C. A. Werlang, N. S. Lewis and H. B.
Gray, ACS Catal., 2013, 3, 166–169.
Y. Shen, Y. Zhou, D. Wang, X. Wu, J. Li and J. Xi, Adv. Energy
Mater., 2018, 8, n/a‐n/a.
S. Wang, J. Wang, M. Zhu, X. Bao, B. Xiao, D. Su, H. Li and Y.
Wang, J. Am. Chem. Soc., 2015, 137, 15753–15759.
Nyquist plots of
with frequencies ranging from 100 KHz to 0.1 Hz are presented
in Figure 5a. The plots show that exhibits good conductivity
1 at different ƞ of 0.25, 0.30, 0.35 and 0.40 V,
1
with relatively small diameters of semicycles. As ƞ increases, the
diameters decrease gradually, implying faster HER kinetics at
higher ƞ.
10 B. Hinnemann, P. G. Moses, J. Bonde, K. P. Jørgensen, J. H.
Nielsen, S. Horch, I. Chorkendorff and J. K. Nørskov, J. Am.
Chem. Soc., 2005, 127, 5308–5309.
11 T. F. Jaramillo, K. P. Jørgensen, J. Bonde, J. H. Nielsen, S. Horch
and I. Chorkendorff, Science, 2007, 317, 100–102.
12 D. Merki, H. Vrubel, L. Rovelli, S. Fierro and X. Hu, Chem. Sci.,
2012, 3, 2515–2525.
13 Y. Wu, M. Zarei‐Chaleshtori, B. Torres, T. Akter, C. Diaz‐Moreno,
G. B. Saupe, J. A. Lopez, R. R. Chianelli and D. Villagrán, Int. J.
Hydrog. Energy, 2017, 42, 20669–20676.
14 J. F. Callejas, C. G. Read, E. J. Popczun, J. M. McEnaney and R. E.
Schaak, Chem. Mater., 2015, 27, 3769–3774.
15 L. Feng, H. Vrubel, M. Bensimon and X. Hu, Phys. Chem. Chem.
Phys., 2014, 16, 5917–5921.
To evaluate the durability of the polymer as HER electrocatalyst,
long‐term chronoamperometric measurement was conducted
using the 1‐modified FTO/silver working electrode. Figure 5b
exhibits the corresponding current density at a controlled
potential of –0.4 V vs. RHE in 0.5 M H2SO4 aqueous solution for
10 hours. It can be seen that the catalyst presents excellent
catalytic stability under 10 h electrocatalysis with almost no
current density decrease. Linear sweep voltammetry using the
rinsed catalyst‐modified working electrode with the attached
catalyst used after 10 h electrolysis in an acid solution of 0.5 M
H2SO4 (Figure S8) shows an overpotential increase of ca. 5 mV
at 10 mA/cm2 which implies minimum catalyst leeching over
long term electrolysis.
16 X. Hu, B. S. Brunschwig and J. C. Peters, J. Am. Chem. Soc., 2007,
129, 8988–8998.
17 J. L. Dempsey, B. S. Brunschwig, J. R. Winkler and H. B. Gray, Acc.
Chem. Res., 2009, 42, 1995–2004.
18 C. C. L. McCrory, C. Uyeda and J. C. Peters, J. Am. Chem. Soc.,
2012, 134, 3164–3170.
19 Y. Wu, N. Rodríguez‐López and D. Villagrán, Chem. Sci., ,
DOI:10.1039/C8SC00093J.
Conclusions
We have compared a crystalline cobalt porphyrin‐based
polymer and a cobalt porphyrin monomer for electrocatalytic
hydrogen gas generation in strong acidic media. The polymer
shows significantly larger surface area and enhanced catalytic
performance compared to the discrete molecule. This gives
strong evidence that by constructing a polymeric system based
on HER electrocatalytic active molecular catalysts can increase
the surface area to therefore enhance the catalytic efficiency.
20 B. C. Patra, S. Khilari, R. N. Manna, S. Mondal, D. Pradhan, A.
Pradhan and A. Bhaumik, ACS Catal., 2017, 7, 6120–6127.
21 S. Bhunia, S. K. Das, R. Jana, S. C. Peter, S. Bhattacharya, M.
Addicoat, A. Bhaumik and A. Pradhan, ACS Appl. Mater.
Interfaces, 2017, 9, 23843–23851.
22 J. Staszak‐Jirkovský, C. D. Malliakas, P. P. Lopes, N. Danilovic, S.
S. Kota, K.‐C. Chang, B. Genorio, D. Strmcnik, V. R. Stamenkovic,
M. G. Kanatzidis and N. M. Markovic, Nat. Mater., 2016, 15,
197–203.
23 I. Bhugun, D. Lexa and J.‐M. Savéant, J. Am. Chem. Soc., 1996,
118, 3982–3983.
24 C. H. Lee, D. K. Dogutan and D. G. Nocera, J. Am. Chem. Soc.,
2011, 133, 8775–8777.
Conflicts of interest
The authors declare no conflicts of interest.
25 B. B. Beyene, S. B. Mane and C.‐H. Hung, Chem. Commun., 2015,
51, 15067–15070.
26 I. Hod, M. D. Sampson, P. Deria, C. P. Kubiak, O. K. Farha and J.
T. Hupp, ACS Catal., 2015, 5, 6302–6309.
Acknowledgements
This work was supported by NSF under award number CHE‐
1305124. And we thank Prof. Geoffrey B. Saupe and Tahmina
Akter for access to the GC instrument.
27 H. Jia, Y. Yao, Y. Gao, D. Lu and P. Du, Chem. Commun., 2016, 52,
13483–13486.
28 S. Cui, M. Qian, X. Liu, Z. Sun and P. Du, ChemSusChem, 2016, 9,
2365–2373.
29 Z.‐S. Wu, L. Chen, J. Liu, K. Parvez, H. Liang, J. Shu, H. Sachdev, R.
Graf, X. Feng and K. Müllen, Adv. Mater., 2014, 26, 1450–1455.
Notes and references
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 5
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