Supporting Information for Active Pt 3 Ni (111) Surface of Pt 3 Ni Icosahedron for Oxygen Reduction Jianbing Zhu,, Meiling Xiao,, Kui Li,, Changpeng Liu, Xiao Zhao*,& and Wei Xing*,, State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China University of Chinese Academy of Sciences, Beijing, 100039, China Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Changchun, Jilin, 130022, China & Department of applied physics and chemistry, The University of Electro-Communications, Chofugaoka Chofu, Tokyo, 182-8585, Japan Email: xingwei@ciac.ac.cn; xiaozhao@uec.ac.jp 1
ORR Measurements Firstly, 2 mg synthetic Pt 3 M/C catalysts were dispersed into 1 ml water/isopropanol/nafion solution (containing 400 µl water, 550 µl isopropanol and 50 µl 5 wt % Nafion solution) by sonication. 10 µl of the dispersion was dispersed on a glassy carbon rotating ring-disk electrode (RRDE, the ring material is Pt), then dried in air. Prior to ORR test, working electrodes were pre-treated by potential cycling in the range of 0.05 1.00V (50 mvs -1, 50 cycles) to remove surface contaminant. The electrochemically active surface area (ECSA) was estimated by H upd and CO stripping experiments. For H upd calculation, the average charge of the Pt-hydrogen adsorption/desorption region after correction for double layer charging and assuming the value of 210 µc cm -2 for the oxidation of a monolayer of hydrogen 1-3. For CO stripping voltammetric experiments, CO was absorbed at 0.02 V for 10 min, excess CO in the electrolyte was then purged out with N 2 for 10 min, and then first two cycles recorded at 20 mv s -1 and assuming the value of 420 µc cm -2 for the oxidation of a monolayer of carbon monoxide. RRDE measurements were conducted by liner sweep voltammetry (LSV) from 0.2 V to 1.1 V (5 mv s -1, 1600 rpm), while the potential of ring electrode was held at 1.3 V. The following equations were used to determine the electron transfer number (n) and the hydrogen peroxide yield (%H 2 O 2 ). = 4 +( / ) % =100 2 / +( / ) (1) (2) I D and I R are the disk and ring currents, respectively. N represents the collection 2
coefficient of H 2 O 2 on the Pt ring. Kinetic current (I k ) was calculated according to the Koutechy-Levich equations: 1 = 1 + 1 (3) =0.62nAFC (D ) / ν (4) in which n is the electron transfer number; F is Faraday's constant (96,485 C mol -1 ); A is the area of the electrode (0:196 cm 2 in this work); D 0 is the diffusion coefficient of O 2 in 0.1M HClO 4 (1:93 10-5 cm 2 s -1 ); ν is the kinematic viscosity of 0.1M HClO 4 (1.01 10-2 cm 2 s -1 ), and C 0 is the concentration of molecular oxygen in 0.1M HClO 4 solution (1.26 10-6 mol cm -3 ) 4. Accelerated durability test (ADT) were conducted by potential cycling from 0.6 to 1.2 V for 20,000 cycles in an N 2 -saturated 0.1M HClO 4 solution at 50 mvs -1. Specific and mass activities were obtained by normalizing the kinetic current density (calculated from the Koutecky-Levich equation) to the mass and ECSA of Pt, respectively. 3
Figure S1 (a) XRD and (b) XPS patterns of Pt/C, Pt NI and Pt 3 Ni catalysts. 4
Figure S2 UV vis absorption of Ni 2+ + Pt 4+ + glunh 2 + H 2 O solution with different reacting temperature. 5
Figure S3 Bright-field TEM images of Pt3Ni nanoparticles obtained from hydrothermal synthesis with different reaction temperature, (a) 140 oc (b) 160 oc, (c) 180 oc, (d) 200 oc. 6
Figure S4 Typical TEM (a), HRTEM (b) and HAADF-STEM (c) images of Pt NI icosahedra 7
Figure S5 TEM, HRTEM and HAADF-STEM images of Pt 3 Fe (a-c), Pt 3 Co (d-f) and Pt 3 Cu (g-i) icosahedral. 8
Figure S6 EDX, EDS line scan and corresponding elements mapping elements mapping of Pt 3 Fe icosahedral. 9
Figure S7 EDX, EDS line scan and corresponding elements mapping elements mapping of Pt 3 Co icosahedral. 10
Figure S8 EDX, EDS line scan and corresponding elements mapping elements mapping of Pt 3 Cu icosahedral. 11
Figure S9 TEM images of Vulcan XC-72 supported catalysts; (a) Pt NI/C; (b) Pt 3 Fe/C; (c) Pt 3 Co/C; (d) Pt 3 Ni/C and (e) Pt 3 Cu/C. 12
Figure S10 XRD patterns of Pt 3 Fe, Pt 3 Co and Pt 3 Cu catalysts. 13
Figure S11 XPS spectra of Pt 4f for Pt/C, Pt 3 Fe/C, Pt 3 Co/C and Pt 3 Cu/C catalysts. 14
Figure S12 XPS spectra for (a) Ni 2p, (b) Fe 2p, (c) Co 2p and (d) Cu 2p. 15
Figure S13 CO-stripping voltammograms of the (a) Pt/C, (b) Pt NI/C, (c) Pt 3 Ni/C, (d) Pt 3 Fe/C, (e) Pt 3 Co/C and (f) Pt 3 Cu/C catalysts in 0.1 M HClO 4 solution at a scan rate of 20 mvs -1. 16
Figure S14 (a) Cyclic voltammetry curves of Pt 3 Fe/C, Pt 3 Co/C and Pt 3 Cu/C catalysts, (b) ORR polarization curves for Pt 3 Fe/C, Pt 3 Co/C and Pt 3 Cu/C catalysts in O 2 -saturated 0.1M HClO 4 at room temperature, with rotation rate, 1,600 r.p.m. and sweep rate, 5mVs -1. (c) Comparison of mass activities for Pt 3 Fe/C, Pt 3 Co/C and Pt 3 Cu/C catalysts at 0.95 and 0.9 V. (d) Comparison of specific activities (I k ). 17
Figure S15 Comparison of specific activities for Pt/C, Pt NI/C, Pt 3 Ni/C, Pt 3 Fe/C, Pt 3 Co/C and Pt 3 Cu/C catalysts at 0.9 V. 18
Figure S16 percentage of peroxide (black line) and corresponding electron transfer number (n) obtained from for rotating ring currents on the RRDE: (a) Pt/C, (b) Pt NI/C, (c) Pt 3 Ni/C, (d) Pt 3 Fe/C, (e) Pt 3 Co/C and (f) Pt 3 Cu/C. 19
Figure S17 TEM image of Pt 3 Ni/C catalyst after ADT test. 20
Figure S18 Pt 4f XPS spectra of Pt3Ni/C catalyst before and after ADT. 21
Figure S19 Cyclic voltammetry curves of (a) Pt NI/C (b) Pt 3 Fe/C, (c) Pt 3 Co/C and (d) Pt 3 Cu/C catalysts in N 2 -purged 0.1M HClO 4 solution at room temperature for various numbers of potential cycles. 22
Figure S20 Comparative ORR activities of (a) Pt NI/C,(b) Pt 3 Fe/C, (c) Pt 3 Co/C and (d) Pt 3 Cu/C catalysts before and after 20,000 potential cycles. 23
Figure S21 Mass activity of the Pt/C, Pt NI/C and Pt 3 M/C catalysts after 20,000 potential cycles at 0.95 and 0.9V. 24
Table S1 Elements content of the Pt 3 M (M= Ni, Fe, Co, Cu) Sample XPS / at% ICP-OES / at% M a Pt a M a Pt a M b Pt b Pt 3 Ni 5.69 94.31 24.5 75.5 22.2 77.8 Pt 3 Fe 4.68 95.32 23.9 76.1 21.4 78.6 Pt 3 Co 4.11 95.89 24.7 75.3 21.9 78.1 Pt 3 Cu 3.08 96.92 23.6 76.4 22.3 77.7 a) The initial elements content of Pt 3 M; b) After ADT test. 25
Table S2 Sum of electrocatalystic performance for Pt 3 M catalysts ECSA/m 2 /g Potential / V Activity@0.9V Tafel Slop H upd CO stripping E onset E 1/2-1 MA/ Amg Pt SA H /Acm -2 SA CO /Acm -2 mv dec -1 Pt 3 Ni/C 27.6 39.9 1.02 0.942 1.761 0.00638 0.00441 45.3 Pt 3 Fe/C 20.8 29.3 1.00 0.912 0.404 0.00194 0.00138 48.6 Pt 3 Co/C 29.2 40.7 1.01 0.923 0.598 0.00205 0.00147 47.4 Pt 3 Cu/C 30.4 42.9 1.01 0.915 0.373 0.00123 0.00087 51.6 Pt NI/C 19.5 22.2 1.00 0.893 0.217 0.00111 0.00098 54.6 Pt/C 60.5 63.8 0.99 0.882 0.146 0.0002 0.00019 58.3 26
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