Supporting Information MOF Templated Nitrogen Doped Carbon Stabilized Pt-Co Bimetallic Nanoparticles: Low Pt Contents and Robust Activity towards Electrocatalytic Oxygen Reduction Reaction Li-Li Ling, Wu-Jun Liu, Si-Qin Chen, Xiao Hu, Hong Jiang* CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China Email: jhong@ustc.edu.cn S-1
S1. Calculation of the parameters of ORR The electron transfer number (n) in ORR can be calculated based on the Koutecky-Levich equations (S1-4) at different electrode potentials: 33 1/J = 1/J k +1/J L = 1/J k + 1/Bω 1/2 (S1) B = 0.2nFC o (D o ) 2/3 υ -1/6 J k = nfkc o J L= 0.2nFC o (D o ) 2/3 υ -1/6 ω 1/2 (S2) (S3) (S4) where J, J k, and J L are the total current density, kinetic- and diffusion-limiting current densities, respectively. ω and n are the angular velocity and electron transfer number in ORR, respectively. F (96485 C mol 1 ) is the Faraday constant. C o and D o are the bulk O 2 concentration of (1.2 10 6 mol cm 3 in 0.1 M of KOH) and O 2 diffusion coefficient (1.9 10 5 cm 2 /s in 0.1 M of KOH), respectively. ν and k are the kinematic electrolyte viscosity (0.01 cm 2 s 1 ) the electron transfer rate constant, respectively. The H 2 O 2 yield and the electron transfer number (n) were calculated by the followed Eqs. S5 and 6, respectively: %HO - I r / N 2 = 200 (S5) I + I / N d r I d n= 4 (S6) I + I / N d r where I d and Ir are the disk and ring current, respectively. N is determined as 0.4 from the reduction of K 3 Fe[CN] 6. S-2
Table S1. Comparison of the Pt contents and ORR performances between the state-of-art Pt based ORR catalysts and the Pt-Co/NC synthesized in this work catalyst Pt content (%) E 1/2 (V) Ref. 5% Pt/FeCo OMPC 5% 0.858 3 Pd-P 11% 0.82 4 Pt NW/C 40% 0.848 5 Pt 3 Co/C 20% 0.825 6 Au-rod@Pt 34% 0.786 7 Pt-Co 6 Mo 6 C 2 /gc 40% 0.92 8 Pt-Co/NC 0.51% 0.87 This work S-3
Figure S1. XRD pattern and SEM image of the ZIF-67 S-4
Figure S2. (a) XPS Co 2p spectra of the Co/NC (b) XPS Co 2p spectra of the Pt-Co/NC. Figure S3. XPS Pt 4f spectra of the Pt-Co/NC S-5
Figure S4. Ring and disk current densities of the Pt-Co/NC in RRDE measurements. S-6
Figure S5. The LSV profiles collected from the catalysts with different Pt contents. S-7
Figure S6. (a) LSV profiles of the Co/NC, Pt-Co/NC, and benchmark 20% Pt/C catalyst in O 2 -saturated 0.1 M HClO 4 solution at room temperature (rotation speed 1600 rpm, sweep rate 5 mv s -1 ); (b) current-time (i-t) chronoamperometric response of NPMAC-495 and Pt/C electrodes at 0.128 V (vs. RHE) in O 2 -saturatured 0.1 M HClO 4 solution at a rotation rate of 900 rpm with the introduction of methanol;(c) current-time (i-t) chronoamperometric response of NC-900-5 and Pt/C electrodes at 0.128 V (vs. RHE) in O 2 -saturatured 0.1 M HClO 4 solution at a rotation rate of 900 rpm. S-8
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