Supplemental Information. Coupled s-p-d Exchange in Facet-Controlled. Pd 3 Pb Tripods Enhances Oxygen. Reduction Catalysis

Transcription

1 Chem, Volume 4 Supplemental Information Coupled s-p-d Exchange in Facet-Controlled Pd 3 Pb Tripods Enhances Oxygen Reduction Catalysis Lingzheng Bu, Qi Shao, Yecan Pi, Jianlin Yao, Mingchuan Luo, Jianping Lang, Sooyeon Hwang, Huolin Xin, Bolong Huang, Jun Guo, Dong Su, Shaojun Guo, and Xiaoqing Huang

2 SUPPLEMENTAL EXERIMENTAL PROCEDURES Chemicals: Palladium(II) acetylacetonate (Pd(acac) 2, 99%), lead(ii) acetylacetonate (Pb(acac) 2, 99%), oleylamine (C 18 H 37 N, OAm, > 70%), oleic acid (C 18 H 34 O 2, OA, > 85%), ascorbic acid (AA, C 6 H 8 O 6, reagent grade, 99%), 1-octadecene (C 18 H 36, ODE, technical grade, 90%), Nafion (5%), and commercial Pd/C (10 wt% Pd) were all purchased from Sigma-Aldrich. Lead(II) chloride (PbCl 2, 99.99%), lead(ii) acetate trihydrate (Pb(Ac) 2 3H 2 O, > 99%) and phloroglucinol (C 6 H 6 O 3, 99%) were obtained from Aladdin. Commercial Pt/C (20 wt%, 2-5 nm Pt nanoparticles) was purchased from Johnson Matthey Corporation. Glucose (C 6 H 12 O 6 H 2 O, analytical reagent), potassium hydroxide (KOH, analytical reagent, 85%), diphenyl ether (C 12 H 10 O, DPE, analytical reagent, 99.0%), cyclohexane (C 6 H 12, analytical reagent, 99.5%), ethanol (C 2 H 6 O, analytical reagent, 99.7%), isopropanol (C 3 H 8 O, analytical reagent, 99.7%) and perchloric acid (HClO 4, analytical reagent, 70%-72%) were obtained from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). All the chemicals were used as received without further purification. The water (18 MΩ/cm) used in all experiments was prepared by passing through an ultra-pure purification system. All chemicals were from commercial suppliers without further purification unless otherwise mentioned. Characterization: Power X-ray diffraction (PXRD) patterns were collected using an X`Pert-Pro X-ray powder diffractometer equipped with a Cu radiation source (λ = nm). The morphology and size of the nanocrystals were determined by transmission electron microscope (TEM, Hitachi, HT7700) at 120 kv. High-resolution TEM (HRTEM), selected-area electron diffraction (SAED), TEM energy dispersive X-ray spectroscopy (TEM-EDS) and high angle annular dark field scanning TEM (HAADF-STEM) were conducted on a FEI Tecnai F20 transmission electron microscope at an acceleration voltage of 200 kv. The TEM work in Brookhaven are performed with a JEOL-2100F (for HRTEM and SAED), a FEI Talos (3D STEM tomography) and aberration corrected HD-2700C (high resolution STEM imaging and STEM-EELS mapping) at an acceleration voltage of 200 kv. All the samples were prepared by dropping cyclohexane dispersion of samples onto carbon-coated copper grids and dried under ambient condition. Low-resolution energy dispersive X-ray spectroscopy was performed on a scanning electron microscope (SEM, Hitachi, S-4700). The concentration of each catalyst was determined by the inductively coupled plasma atomic emission spectroscopy (710-ES, Varian, ICP-AES).

3 Figure S1. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing the amount of Pd(acac) 2 to (A, B) 3.8 mg and (C, D) 15.2 mg, respectively. Related to Figure 1.

4 Figure S2. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing the amount of Pb(acac) 2 supplied to (A, B) 2 mg and (C, D) 8 mg, respectively. Related to Figure 1.

5 Figure S3. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing 4.0 mg Pb(acac) 2 with (A, B) 2.8 mg PbCl 2 and (C, D) 3.8 mg Pb(Ac) 2 3H 2 O, respectively. Related to Figure 1.

6 Figure S4. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing the amount of phloroglucinol to (A, B) 20 mg and (C, D) 60 mg, respectively. Related to Figure 1.

7 Figure S5. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing 40 mg phloroglucinol with (A, B) 35.6 mg AA and (C, D) 60 mg glucose, respectively. Related to Figure 1.

8 Figure S6. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing 4 ml OAm + 1 ml OA with (A, B) 5 ml OAm, (C, D) 4 ml OAm + 1 ml ODE, and (E, F) 4 ml OAm + 1 ml DPE, respectively. Related to Figure 1.

9 Figure S7. TEM images of the products collected from the reaction with the same condition used in the synthesis of Pd 3 Pb TPs but changing 4 ml OAm + 1 ml OA with (A, B) 4.5 ml OAm ml OA and (C, D) 3.5 ml OAm ml OA, respectively. Related to Figure 1.

10 Figure S8. (A, B) TEM images, (C, D) STEM images, (E) length distribution, (F) diameter distribution, (G) TEM-EDS and (H) HAADF-STEM images at different viewing angles from -55ºto +55ºof the intermetallic Pd 3 Pb TPs. Related to Figure 1.

11 Figure S9. (A) TEM image, (B, C) HRTEM images, and (D) the selected area electron diffraction (SAED) pattern of one single Pd 3 Pb TP. (E) The additional HAADF-STEM image and the corresponding elemental mappings of an individual Pd 3 Pb TP. Related to Figure 1.

12 Figure S10. (A-C) simulated electron diffraction patterns along <100>, <110> and <112> zone axes. (D-F) the corresponding fast Fourier transition (FFT) patterns from high resolution STEM images along the three zone axes. Related to Figure 2.

13 Figure S11. (A) The low-magnification TEM and (B-D) HRTEM images from an individual Pd 3 Pb TP along [110] direction. The inset in (A) is the corresponding FFT pattern. Related to Figure 2.

14 Figure S12. (A) The low-magnification and (B) high-magnification TEM images along [112] direction, (C) high resolution HAADF-STEM image, and (D) HRTEM image from an individual Pd 3 Pb TP. The inset in (A) is the corresponding FFT pattern. The inset in (B) is the atomic model, showing the orientation. Related to Figure 2.

15 Figure S13. (A) ADF image of one branch of Pd 3 Pb TP. (B) STEM-EELS line scan of Pd and Pb crossing the branch of (A). Related to Figure 2.

16 Figure S14. (A, B) STEM images, (C) PXRD pattern, (D) TEM-EDS, (E) HRTEM image and (F) HAADF-STEM image and the corresponding elemental mappings of the Pd 3 Pb NPs. Related to Figure 3.

17 Figure S15. (A, B) TEM images and (C) SEM-EDX of the Pd 3 Pb TPs/C before electrochemical tests. Related to Figure 3.

18 Figure S16. (A) TEM image, (B, C) HRTEM images, (D) HAADF-STEM image and the corresponding elemental mappings of the Pd 3 Pb TPs/C before electrochemical tests. Related to Figure 3.

19 Figure S17. (A) TEM image and (B) SEM-EDX of the Pd 3 Pb NPs/C before electrochemical tests. Related to Figure 3.

20 Figure S18. ORR polarization curves of (A) the Pd 3 Pb NPs/C, (B) the commercial Pt/C and (C) the commercial Pd/C before and after different potential cycles. Related to Figure 3.

21 Figure S19. (A, B) TEM images and (C) SEM-EDX of the Pd 3 Pb TPs/C after 20,000 potential cycles. Related to Figure 3.

22 Figure S20. (A) TEM image, (B, C) HRTEM images, and (D) HAADF-STEM image and the corresponding elemental mappings of the Pd 3 Pb TPs/C after 20,000 potential cycles. Related to Figure 3.

23 Figure S21. (A) TEM image and (B) SEM-EDX of the Pd 3 Pb NPs/C after 20,000 potential cycles. Related to Figure 3.

24 Figure S22. TEM images and size distribution of the commercial Pt/C (A, B, C) before and (D, E, F) after 20,000 potential cycles. Related to Figure 3.

25 Figure S23. TEM images of the commercial Pd/C (A, B) before and (C, D) after 20,000 potential cycles. Related to Figure 3.

26 Figure S24. Calculated band structure and projected density of states (PDOS) for Pd 3 Pb fcc lattice. Related to Figure 4.

27 Figure S25. The free energy profiles G of four-electron-based ORR process on the Pd 3 Pb (110), and the TS represents transition states. The symbol * denotes the molecule absorbed on the specific site of the surface. Related to Figure 4.

28 Figure S26. Projected DOS of Pd 3 Pb (110) surface. (A) d-orbitals, (B) s-orbitals, and (C) p-orbitals of Pd-Pb sites on Pd 3 Pb (110) surface. (D) The combined PDOS analysis is given on the bulk-d. Related to Figure 4.

29 Figure S27. Obtained values of U out1 and U out2 for (A) 4d orbital of Pd in Pd 3 Pb within fcc lattice. (B) 4d orbital of Pd on the topmost layer of Pd 3 Pb (110) surface. (C) 4d orbital of Pd on the topmost layer of Pd 3 Pb (100) surface. The crossover feature indicates U out1 - U out2 = 0 denotes the fully occupied orbitals of 4d in Pd site. Related to Figure 4.

30 Figure S28. Calibration of SCE and conversion to RHE in (A) 0.1 M HClO 4 solution and (B) 0.1 M KOH solution. The calibration of SCE reference electrode is performed in a standard three-electrode system with polished Pt wires as the working and counter electrodes, and the SCE as the reference electrode. Electrolytes are pre-purged and saturated with high purity H 2. Linear scanning voltammetry (LSV) is then run at a scan rate of 0.1 mv s -1, and the potential at which the current crossed zero is taken to be the thermodynamic potential (vs. SCE) for the hydrogen electrode reactions. In 0.1 M HClO 4 solution, the zero current point is at V, so E (RHE) = E (SCE) V. In 0.1 M KOH solution, the zero current point is at V, so E (RHE) = E (SCE) V. Related to Figure 3.

31 Table S1. ORR activities at 0.90 V vs RHE for commercial Pd/C, commercial Pt/C, Pd 3 Pb NPs/C and Pd 3 Pb TPs/C. ORR measurements were performed at room temperature in O 2 -saturated 0.1 M KOH solutions with a sweep rate of 10 mv s -1 and a rotation rate of 1600 rpm. The activities and standard deviations were calculated based on five parallel measurements after Ohmic drop correction. Related to Figure 3. Catalysts Loading amounts of metal Pd/Pt (μg) Mass Activities (A mg Pd/Pt -1 ) Specific Activities (ma cm -2 ) Pd/C ± ± 0.04 Pt/C ± ± 0.04 Pd 3 Pb NPs/C ± ± 0.06 Pd 3 Pb TPs/C ± ± 0.07

32 Table S2. ORR performance of Pd 3 Pb TPs/C catalyst and state-of-art Pd-based ORR nanocatalysts from recent published works in alkaline medium. Related to Figure 3. No. Catalysts Mass Activities (A mg Pd -1 ) Specific Activities (ma cm -2 ) References 1 Pd 3 Pb TPs/C 0.90 V vs. RHE 0.85 V vs. RHE 0.90 V vs. RHE 0.85 V vs. RHE This work 2 Pd-P (3) 0.85 V vs. RHE 0.85 V vs. RHE 3 Pd-N 2 H 4 (3) 0.85 V vs. RHE 0.85 V vs. RHE 4 Pd-P (9) 0.85 V vs. RHE 0.85 V vs. RHE 5 Pd-N 2 H 4 (9) 0.85 V vs. RHE 0.85 V vs. RHE (1) 6 Pd-P (18) 0.85 V vs. RHE 0.85 V vs. RHE 7 Pd-N 2 H 4 (18) 0.85 V vs. RHE 0.85 V vs. RHE 8 Pd nanoparticles 0.90 V vs. RHE 0.90 V vs. RHE (2) 9 Pd/W 18 O 49 hybrids 0.90 V vs. RHE 0.90 V vs. RHE 10 Ordered Pd 3 Pb/C 11 Ordered Pd 3 Fe/C 0.90 V vs. RHE 0.90 V vs. RHE N/A (3) N/A (4) Ag/Cu 37 Pd 63 nanoparticles Au/Cu 40 Pd 60 nanoparticles V vs. Ag/AgCl (4 M KCl) V vs. Ag/AgCl (4 M KCl) N/A N/A (5) PdCuCo NPs/C-375 º C AuPdCo/C Intermetallic (800 º C) 0.90 V vs. RHE N/A (6) 0.90 V vs. RHE N/A (7) NA: not available Note: All the ORR measurements were performed at room temperature in O 2 -saturated 0.1 M KOH solutions with a sweep rate of 10 mv s -1 and a rotation rate of 1600 rpm.

33 Table S3. ORR performance of Pd 3 Pb TPs/C and various Pt-based ORR nanocatalysts from recent published works in alkaline medium. Related to Figure 3. No. Catalysts Mass Activities (A mg Pd/Pt -1 ) Specific Activities (ma cm -2 ) References 1 Pd 3 Pb TPs/C 0.90 V vs. RHE 0.85 V vs. RHE 0.90 V vs. RHE 0.85 V vs. RHE This work 2 NiPt NPs 0.90 V vs. RHE 0.90 V vs. RHE 3 NiPt TONPs 0.90 V vs. RHE 0.90 V vs. RHE 4 Pt/C 0.90 V vs. RHE 0.90 V vs. RHE 5 CuPt-NC 0.90 V vs. RHE 0.90 V vs. RHE (8) (9) 6 Pt 3 Co alloy electrode 0.90 V vs. RHE a N/A (10) 7 E-Tek Pt/C V vs. Ag/AgCl V vs. Ag/AgCl (11) nm Pt-Fe 3 O 4 NPs -0.1 V N/A (12) vs. Hg/HgO b 9 Pt NPs/Ti 0.5 Nb 0.5 N 0.90 V N/A (13) vs. RHE c 10 Pt/ITO catalyst 0.10 V vs. NHE c 0.10 V vs. NHE c (14) 11 Pt NPs N/A 0.90 V vs. RHE 12 Pt-coated Pd nanocubes N/A 0.90 V vs. RHE (15) 13 Pt/C (JM) 0.85 V vs. RHE c 0.85 V vs. RHE c 14 Pt/CaMnO 3 nanocomposites 0.85 V vs. RHE c 0.85 V vs. RHE c (16) 15 H-Pt/CaMnO 3 nanocomposites 0.85 V vs. RHE c 0.85 V vs. RHE c NA: not available Note: Except the following specific illustrations, all the ORR measurements were performed at room temperature in O 2 -saturated 0.1 M KOH solutions with a sweep rate of 10 mv s -1 and a rotation rate of 1600 rpm.

34 a: The ORR measurements were carried out in O 2 -saturated 0.1 M NaOH solutions with a sweep rate of 20 mv s -1 and a rotation rate of 1600 rpm. b: The ORR measurements were carried out in O 2 -saturated 0.5 M KOH solutions with a sweep rate of 10 mv s -1 and a rotation rate of 1600 rpm. c: The ORR measurements were carried out in O 2 -saturated 0.1 M KOH solutions with a sweep rate of 5 mv s -1 and a rotation rate of 1600 rpm.

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