Supporting Information

Transcription

1 Supporting Information Bio-Inspired Engineering of Cobalt-Phosphonate Nanosheets for Robust Hydrogen Evolution Reaction Zhong-Sheng Cai, 1, Yi Shi, 2, Song-Song Bao, 1 Yang Shen, 1 Xing-Hua Xia,*,2 and Li-Min Zheng*,1 1 State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing , P. R. China 2 State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing , P. R. China Corresponding authors: lmzheng@nju.edu.cn; xhxia@nju.edu.cn These authors contributed equally. S1

2 Table S1. Crystallographic data for 1Co. Temperature 298 K V (Å 3 ) (11) Empirical formula C 7 H 9 CoO 5 P Z 4 Fw ρ calcd (g cm -3 ) Crystal system monoclinic F(000) 532 Space group P2 1 /n GOF a (Å) (4) R1, wr2 [I >2σ(I)] a , b (Å) (2) R1, wr2 (all data) a , c (Å) (4) ( ρ) max, ( ρ) min / e Å , β (deg) (1) CCDC number a R 1 = Σ F o - F c /Σ F o. wr 2 = [Σw(F 2 o -F 2 c ) 2 /Σw(F 2 o ) 2 ] 1/2 Table S2. Selected bond lengths [Å] and angles [deg] for 1Co. Co1-O (18) O1-Co1-O2B 97.91(7) Co1-O1W 2.113(2) O1-Co1-O1C (7) Co1-O (18) O1W-Co1-O (7) Co1-O3A (18) O1W-Co1-O3A (8) Co1-O2B (18) O1W-Co1-O2B 93.99(7) Co1-O1C (18) O1C-Co1-O1W 91.37(7) P1-O (19) O2-Co1-O3A 87.18(7) P1-O (19) O2-Co1-O2B (7) P1-O (2) O1C-Co1-O (7) O1-Co1-O1W 89.03(7) O2B-Co1-O3A 89.87(7) O1-Co1-O (6) O1C-Co1-O3A 92.17(7) O1-Co1-O3A 86.05(7) O1C-Co1-O2B (7) Symmetry codes: A: 1+x, y, z; B: 1/2+x, 1/2-y, -1/2+z; C: 1/2+x, 1/2-y, 1/2+z Table S3. Fitting parameters of the PXRD patterns of compounds 1Mn, 1Fe, 1Ni and 1Cu. Compound 1Mn 1Fe 1Ni 1Cu Space group P2 1 /n P2 1 /n P2 1 /n P2 1 /n Scale a (Å) b (Å) c (Å) β (deg) V (Å 3 ) GOF R wp S2

3 Table S4. HER activities of various catalysts in neutral solution. Catalysts Overpot ential/ mv Tafel slope/ mv dec 1 η/ mv TOF/ s -1 Reference 1Co-ns In this work Ni-S film N/A N/A J. Mater. Chem. A, 2014, 2, Co-P-B/rGO N/A N/A J. Mater. Chem. A, 2014, 2, Co-S film J. Am. Chem. Soc., 2013, 135, Co 2 L 2 (SO 4 ) 2 ( H 2 O) N/A N/A N/A CrystEngComm., 2014, 16, 8492 FePS 3 rgo 5 55 N/A N/A N/A ACS Energy Lett., 2016, 1, WP NAs/CC N/A N/A ACS Appl. Mater. Interfaces, , 6, FeP/CC N/A N/A ACS Appl. Mater. Interfaces, 2014, 6, H 2 -CoCat N/A N/A Nature Mater., 2012, 11, 802 Cu 2 MoS 4 /FT O N/A N/A Energy Environ. Sci., 2012, 5, Co-MoS 3 film N/A N/A Chem. Sci., 2012, 3, 2515 MoS 3 film N/A N/A Chem. Sci., 2012, 3, 2515 Co 2 P/NPG N/A N/A Nano lett., 2016, 16, 4691 S3

4 Table S5. Comparative overpotentials of HER activity on different electrocatalysts in the neutral solution and the seawater. Catalyst Neutral solution Seawater Reference 1Co-ns 84 mv 205 mv In this work cobalt-sulfide film 43 mv ~500 mv J. Am. Chem. Soc., 2013, 135, Co P B/rGO 168 mv ~200 mv J. Mater. Chem. A, FePS j =-10 ma cm -2 rgo-feps j = -10 Co/N-codoped nanocarbon ma cm j = -10 ma cm , 2, j=-10 ACS Energy Lett., 2016, ma cm -2 1, j=-10 ACS Energy Lett., 2016, ma cm -2 1, j=-10 Nanoscale, 2015, 7, ma cm S4

5 Calculation of TOF The turn over number (TOF) was calculated from the HER polarization curve in Figure 3a. The total number of active sites was determined from the ICP-OES result. Number of active sites (in mol) for 1Co-ns, m = 3.26 x 10-8 mol From the number of active sites, the per-site turnover frequency (in s -1 ) was calculated using the following equation: TOF=J A/2 F m (1) where J stands for the anodic current density, A stands for the electrode surface area, F is the Faraday constant (96485 C mol -1 ) and m is the mole amount of Co 2+ ions. The factor 1/2 in the equation represents that two electrons are required to form one hydrogen molecule from two protons (2H + +2e - = H 2 ). TOF for 1Co-ns = s V vs. RHE (2) S5

6 Figure S1. Calibration of the Ag/AgCl electrode. Variation in the potential difference between the Ag/AgCl and RHE reference electrodes with time in 0.1 M N 2 -saturated tris- HNO 3 (ph = 7.4) neutral aqueous solution. Figure S2. SEM image of 1Co bulk. S6

7 Figure S3. Left: Light floccules obtained after the reaction of Co(CH 3 COO) 2 and 3-moppH 2 in water at room temperature under sonication. Right: Gel-like state of the floccules after the addition of a small amount of water. Figure S4. SEM image of the floccules. Up panel shows the element mapping images of Co, P, C, and O in the floccules. S7

8 Figure S5. The energy dispersive X-ray spectroscopy (EDS) pattern (left) of the floccules and the corresponding element amount (right). Figure S6. XPS spectra of 1Co. S8

9 Figure S7. XPS spectra of the floccules of 1Co (1Co-ns). The chemical nature of the sub-monolayer sample was investigated by X-ray photoelectron spectroscopy (XPS). Each element has characteristic binding energies associated with electronic transitions from each of its core atomic orbitals, which together with small shifts from the chemical environment, give rise to a characteristic set of peaks in the XPS spectrum. As observed, the XPS spectra of 1Co and 1Co-ns show the presence of cobalt, phosphorus and oxygen (Figures S6 and S7). The P2p region of both samples exhibits two sharp peaks with ev and ev binding energies (area ratio of 2:1) corresponding to the 2p3/2 and 2p1/2 core levels of the central phosphorus atoms in the phosphate species. In the Co region, two broad sets of signals corresponding to the 2p3/2 (781.9 ev) and 2p1/2 (797.8 ev) core levels are observed. The O1s signals are centered for both materials at ev. The P/Co/O atomic ratios for Co-ns (7.09:6.09:29.58) are similar to those of Co-bulk (7.75:6.52:32.23), indicating the same atomic composition. As the Co2p, P 2p and O1s signals of the 1Co and 1Co-ns are nearly in the same range as those of the cobalt phosphate inorganic compound, we tentatively conclude that the epitaxial organic skeleton helps optimize the electronic states of this coordination, further influencing the chemical nature and potential applications. S9

10 Figure S8. AFM image of 1Co-ns dispersed in water with the corresponding height values. Figure S9. The 3D visualization of the AFM image in Figure S8. Height / nm nm 1.48 nm 1.49 nm 1.49 nm 1.48 nm Distance / µm Height / nm nm 1.48 nm 1.55 nm 1.52 nm 1.51 nm Distance / µm Figure S10. The corresponding height profile with the same number labeling as shown in Figure S S10

11 Figure S11. PXRD patterns for the 1Co samples obtained by routes a and route b. Transmittance / a.u. 1Co-route Co-bulk-route a a 1Co-route Co-bulk-route b b Wavenumber / cm -1 Figure S12. IR spectra for the 1Co samples obtained by routes a and route b. S11

12 Figure S13. (A) HER polarization curves in tris-hno 3 solution (ph=7.4) obtained on 1Co-ns with different loading amount as indicated. (B) Tafel plots of 1Co-ns with the corresponding loading amounts derived from the early stages of the HER polarization curves. Figure S14. HER polarization curves in tris-hno 3 solution (ph=7.4) obtained on several catalysts as indicated in the figure. S12

13 Figure S15. (A) HER polarization curves obtained on 1Co-ns in D 2 O and H 2 O solution of tris-hno 3 (ph=7.4) as indicated in the figure. (B) Tafel plots of 1Co-ns in the corresponding solution derived from the early stages of the HER polarization curves. Figure S16. HER polarization curves of the 1Co-ns catalyst in 0.5 M H 2 SO 4 solution and tris- HNO 3 solution (ph=7.4). S13

14 Figure S17. HER polarization curves of the 1Co-ns catalyst in tris-hno 3 solution at different ph values (as indicated in the figure). Figure S18. HER polarization curves in artificial seawater obtained on 1Co-ns with different loading amounts as indicated. S14

15 Figure S19. (A) Electrochemical device used in the gas chromatography (GC) measurements. (B) GC measurements of products catalyzed by 1Co-ns in the artificial seawater. H 2 -standard: pure H 2 collected from the gas cylinder; H 2 -product: gas collected from the working electrode. Transmittance / a.u. Mn-bulk Fe-bulk Co-bulk Ni-bulk Cu-bulk Wavenumber / cm -1 Figure S20. IR spectra of 1Mn, 1Fe, 1Co, 1Ni, and 1Cu. S15

16 Weight / % Mn-bulk Co-bulk Ni-bulk Fe-bulk Co-ns Cu-bulk T / o C Figure S21. TG curves of 1Mn, 1Fe, 1Co, 1Ni and 1Cu. S16

17 S ,200 2,100 2,000 1,900 1,800 1,700 1,600 1,500 1,400 1,300 1,200 1,100 1, hkl_phase 0.00 % ,000 16,000 15,000 14,000 13,000 12,000 11,000 10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1, ,000-2,000-3,000-4,000-5,000-6,000-7,000-8,000-9, ,000 3,800 3,600 3,400 3,200 3,000 2,800 2,600 2,400 2,200 2,000 1,800 1,600 1,400 1,200 1, ,500 1,400 1,300 1,200 1,100 1, hkl_phase 0.00 % Figure S22. The PXRD patterns of 1Mn, 1Fe, 1Co, 1Ni and 1Cu. 1Mn 1Fe 1Ni 1Cu

18 Figure S23. XPS spectra of 1Mn. Figure S24. XPS spectra of 1Fe. Figure S25. XPS spectra of 1Ni. S18

19 Figure S26. XPS spectra of 1Cu. Figure S27. (A) HER polarization curves obtained on several catalysts with different metal centers in 0.5 M H 2 SO 4 solution at 20 mvs -1. (B) Relationship between the HER electrocatalytic activity and the number of d electrons of the center transition metal (Mn II, Fe II, Co II, Ni II, and Cu II ). The current densities were obtained at V (vs. RHE). The dashed volcano line is shown for guidance only. S19

20 References: 1. Jiang, N.; Bogoev, L.; Popova, M.; Gul, S.; Yano, J.; Sun, Y. Electrodeposited nickelsulfide films as competent hydrogen evolution catalysts in neutral water. J. Mater. Chem. A 2014, 2, Li, P. P.; Jin, Z. Y.; Xiao, D. A one-step synthesis of Co P B/rGO at room temperature with synergistically enhanced electrocatalytic activity in neutral solution. J. Mater. Chem. A, 2014, 2, Sun, Y.; Liu, C.; Grauer, D. C.; Yano, J.; Long, J. R.; Yang, P.; Chang, C. J. Electrodeposited cobalt-sulfide catalyst for electrochemical and photoelectrochemical hydrogen generation from water. J. Am. Chem. Soc. 2013, 135, Gao, X. L.; Gong, Y.; Zhang, P.; Yang, Y. X.; Meng, J. P.; Zhang, M. M.; Yin, J. L.; Lin, J. H. Metal(II) complexes based on 4-(2,6-di(pyridin-4-yl)pyridin-4-yl)benzonitrile: structures and electrocatalysis in hydrogen evolution reaction from water. CrystEngComm. 2014, 16, Mukherjee, D.; Austeria, P. M.; Sampath, S. Two-dimensional, few-layer phosphochalcogenide, FePS 3 : a new catalyst for electrochemical hydrogen evolution over wide ph range. ACS Energy Lett. 2016, 1, Pu, Z.; Liu, Q.; Asiri, A. M.; Sun, X. Tungsten phosphide nanorod arrays directly grown on carbon cloth: a highly efficient and stable hydrogen evolution cathode at all ph values. ACS Appl. Mater. Interfaces 2014, 6, Tian, J. Q.; Liu, Q.; Liang, Y. H.; Xing, Z. C.; Abdullah, M. A.; Sun, X. P. FeP nanoparticles film grown on carbon cloth: an ultrahighly active 3D hydrogen evolution cathode in both acidic and neutral solutions. ACS Appl. Mater. Interfaces 2014, 6, Cobo, S.; Heidkamp, J.; Jacques, P. A.; Fize, J.; Fourmond, V.; Guetaz, L.; Jousselme, B.; Ivanova, V.; Dau, H.; Palacin, S.; Fontecave, M.; Artero, V. A Janus cobalt-based catalytic material for electro-splitting of water. Nat. Mater. 2012, 11, Tran, P. D.; Nguyen, M.; Pramana, S. S.; Bhattacharjee, A.; Chiam, S. Y.; Fize, J.; Field, M. J.; Artero, V.; Wong, L. H.; Loo, J.; Barber, J. Copper molybdenum sulfide: a new efficient electrocatalyst for hydrogen production from water. Energy Environ. Sci. 2012, 5, Merki, D.; Vrubel, H.; Rovelli, L.; Fierro, S.; Hu, X. L. Fe, Co, and Ni ions promote the catalytic activity of amorphous molybdenum sulfide films for hydrogen evolution. Chem. Sci. 2012, 3, S20

21 11. Zhuang, M. H.; Ou, X. W.; Dou, Y. B.; Zhang, L. L.; Zhang, Q. C.; Wu, R. Z.; Ding, Y.; Shao, M. H.; Luo, Z. T. Polymer-embedded fabrication of Co 2 P nanoparticles encapsulated in N,P-doped graphene for hydrogen generation. Nano lett. 2016, 16, S21