Supporting Information NiO/CoN Porous Nanowires as Efficient Bifunctional Catalysts for Zn Air Batteries Jie Yin, Yuxuan Li, Fan Lv, Qiaohui Fan, Yong-Qing Zhao, Qiaolan Zhang, Wei Wang, Fangyi Cheng, Pinxian Xi,*, and Shaojun Guo*,,&,% State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China. Department of Materials Science & Engineering, College of Engineering, Peking University, Beijing 100871, China. & BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China. % Key Laboratory of Theory and Technology of Advanced Batteries Materials, College of Engineering, Peking University, Beijing 100871, China. Key Laboratory of Petroleum Resources, Gansu Province/Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou 730000, P. R. China Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, P. R. China Figure S1. (a) TEM and (b) HRTEM images of NiCo 2 O 4 NWs. 1
Figure S2. Electron spin resonance spectra of NiO/CoN PINWs and NiCo 2 O 4 NWs. Figure S3. The CV curves of (a) NiO/CoN PINWs and (b) NiCo 2 O 4 NWs at different scan rate. Figure S4. (a) Ring current of NiO/CoN PINWs on an RRDE (1600 rpm) in O 2 saturated 0.1 M KOH solution (ring potential 1.50 V). (b) Ring current of NiO/CoN PINWs on an RRDE (1600 rpm) in N 2 saturated 0.1 M KOH solution (ring potential 0.40 V). 2
Figure S5. The amount of theoretically calculated (black line) and experimentally measured (red line) oxygen versus time for NiO/CoN PINWs at 0.8 V vs. RHE. Figure S6. (a) XRD pattern of NiO/CoN PINWs before and after OER catalysis. (b) TEM image and the elemental mapping of NiO/CoN PINWs after OER catalysis. Figure S7. LSV curves of (a) NiO/CoN PINWs, (b) NiCo 2 O 4 NWs, (c) Ir/C (20 %) and (d) Pt/C (20 %) at different rotating speeds. 3
Figure S8. LSV curve of NiO/CoN PINWs for ORR before and after 10,000 CV cycles from 0 to 0.4 V vs. Ag/AgCl with a scan rate of 100 mv s 1. Figure S9. (a) Discharge curves of the primary Zn air battery with NiO/CoN PINWs as the air cathode at different current densities. (b) Specific capacities of the primary Zn air battery with NiO/CoN PINWs as the air cathode, normalized to the weight of consumed Zn. Figure S10. (a) Zn spring is coated with a hydrogel polymer electrolyte solution, which is about 14 cm length. (b) Photographs show the assembly of NiO/CoN PINWs for Zn air battery. (c) Photograph of red and blue LED powered by two-series batteries. (d, e) Photograph of single and three-series solid batteries with the open circuit voltage of 1.205 and 3.310 V, respectively. 4
Figure S11. Long-time galvanostatic discharge curves of NiO/CoN PINWs built in Zn air battery. (a) single solid battery and (b) three-series solid batteries at the current densities of 0.5 and 1 ma cm 2, respectively. Figure S12. Photographs show the three-series solid batteries driving a timer work continuously more than 12 h. Table S1. EXAFS fitting results for Ni center and Co center for the two catalysts investigated. CNs = Coordination Numbers, R = Vector distance (± 0.02 Å), σ 2 = Debye Waller factor (± 0.001 Å 2 ). Vector NiO/CoN PINWs NiCo 2 O 4 NWs Vector CNs R (Å) σ 2 (Å) CNs R (Å) σ 2 (Å) Ni O 6.000 2.076 0.00911 Ni O 6.000 1.978 0.00740 Ni Ni 1 6.000 2.967 0.00800 Ni Co 1 6.000 2.892 0.00860 Ni Ni 2 6.000 2.980 0.00900 Ni Co 2 6.000 3.378 0.00980 Co N 4.000 2.114 0.00798 Co O 6.656 1.856 0.00952 Co Co 8.400 2.994 0.00729 Co Co 21.600 3.270 0.01766 5
Table S2. Comparison of the OER performance for all used catalysts. η at j = 10 Tafel Slope Electrodes ma cm 2 (mv dec 1 ) (mv vs. RHE) NiO/CoN PINWs 300 35 Ir/C (20 %) 310 50 Stability 30,000 cycles 48 h (7.56 % loss) 10,000 cycles 24 h (27.67 % loss) TOF at Mass activity at η η = 400 mv = 400 mv (s 1 ) (A g 1 ) 0.132 853.0 0.118 238.5 NiCo 2 O 4 NWs 325 89-0.0284 169.2 Table S3. EXAFS fitting results for Ni center and Co center for the NiO/CoN PINWs before and after OER. CNs = Coordination Numbers, R = Vector distance (± 0.02 Å), σ 2 = Debye Waller factor (± 0.001 Å 2 ). Vector Before OER After OER CNs R (Å) σ 2 (Å) CNs R (Å) σ 2 (Å) Ni O 6.000 2.076 0.00911 6.000 2.076 0.0100 Ni Ni 1 6.000 2.967 0.00800 6.000 2.967 0.00870 Ni Ni 2 6.000 2.980 0.00900 6.000 2.980 0.00900 Co N 4.000 2.114 0.00798 5.292 2.111 0.00952 Co Co 8.400 2.994 0.00729 10.440 2.998 0.01766 Table S4. The ORR activities of different catalysts prepared in this work. Electrodes Onset η (V vs. RHE) Half-wave potential E 1/2 (V vs. RHE) Tafel Slope (mv dec 1 ) Limiting current density (ma cm 2 ) Electron transfer number (n) Pt/C (20 %) 0.95 0.78 60 5.91 4.08 Ir/C (20 %) 0.85 0.67 98 3.91 3.34 NiO/CoN PINWs 0.89 0.68 86 4.42 3.97 NiCo 2 O 4 NWs 0.86 0.65 138 3.54 2.25 6
Table S5. The Ε comparison of NiO/CoN PINWs, Ir/C (20 %) and Pt/C (20 %). Catalysts E OER at j = 10 E ORR at j = 3 ma cm 2 (V) ma cm 2 (V) Ε = E OER - E ORR (V) NiO/CoN PINWs 1.55 0.67 0.88 Ir/C (20 %) 1.54 0.63 0.91 Pt/C (20 %) 1.91 0.78 1.13 Table S6. The electrocatalytic activities of the recently reported bifunctional catalysts for ORR/OER. Catalysts NiO/CoN PINWs N/P co-doped foam NCNF-1000 P-doped g-c 3 N 4 /CFP N-doped graphene/cnt Fe@N-C Fe/C/N NCNT/CoO-NiO -NiCo Co 3 O 4 microtube arrays single-crystal CoO nanorods CFP/NiCo 2 O 4 /Co 0.57Ni 0.43 LMOs CoMnLDH ORR ORR OER OER onset onset half-wave Potential at j potential Support potential potential = 10 ma cm 2 (V vs. (V vs. (E 1/2 ) (E j=10 ) RHE) RHE) (V vs. RHE) (V vs. RHE) Carbon cloth 0.89 0.68 1.50 1.53 Carbon cloth TOF E for OER (E j=10 -E 1/2 ) Ref OER stability (V vs. RHE) (s 1 ) 0.132 This 48 h 0.85 (400 mv) work 0.94 0.85 1.30 S1 0.97 0.85 1.43 1.84 1.02 S2 0.94 0.67 1.53 1.63 15 h 0.96 S3 0.88 0.63 1.50 1.63 1.00 S4 0.96 0.83 1.52 1.71 0.88 S5 0.95 0.83 1.50 1.59 50 cycles 0.76 S6 0.97 0.83 1.50 S7 Ni foam 1.52 12 h S8 Carbon cloth Carbon cloth 0.96 0.85 1.56 10 h 0.71 S9 1.32 1.57 1.554 0.0446 (300 mv) 6 h S10 1.05 (350 mv) 14 S11 7
Table S7. The performance of rechargeable Zn air batteries with various electrocatalysts. open Voltage specific energy Peak power Electrode circuit at 10 capacity at 10 density at Catalysts density Ref preparation potential ma cm 2 ma cm 2 10 ma cm 2 (mw cm 2 ) (V) (V) (ma h g 1 ) (Wh Kg 1 ) NiO/CoN PINWs Self-supported 1.46 1.28 79.6 648 836 This work NCNF Loading on CFP 1.48 1.24 185 626 776 S2 (2 mg cm 2 ) ZnCo 2 O 4 /N-CNT Loading on CFP 1.47 1.33 82.3 428.47 595.57 S12 (2 mg cm 2 ) N/S-2DPC-60 Loading on CFP 0.75 0.69 S13 Loading on CFP NGM (0.8 mg cm 2 ) loaded onto gas N,P-CGHNs diffusion layer 1.42 3.0 S14 1.50 872 Wh 712 ma h g 1 at Kg 1 at 5 S15 5 ma cm 2 ma cm 2 2DBN-800 Loading on CFP 1.40 23.9 S16 nickel mesh NCNT/CoO-NiO-NiCo (0.53 mg cm 2 ) 1.2 615 Wh 545 ma h g 1 at Kg 1 at 20 S7 20 ma cm 2 ma cm 2 References S1. Zhang, J.; Zhao, Z.; Xia, Z.; Dai, Li. A Metal-free Bifunctional Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions. Nat. Nanotechnol. 2015, 10, 444 452. S2. Liu, Q.; Wang, Y.; Dai, L.; Yao, J. Scalable Fabrication of Nanoporous Carbon Fiber Films as Bifunctional Catalytic Electrodes for Flexible Zn Air Batteries. Adv. Mater. 2016, 28, 3000 3006. S3. Ma, T.; Ran, J.; Dai, S.; Jaroniec, M.; Qiao, S. Phosphorus-Doped Graphitic Carbon Nitrides Grown in Situ on Carbon-Fiber Paper: Flexible and Reversible Oxygen Electrodes. Angew. Chem. Int. Ed. 2015, 54, 4646 4650. S4. Tian, G.; Zhao, M.; Yu, D.; Kong, Y.; Huang, J.; Zhang, Q.; Wei, F. Nitrogen-Doped Graphene/Carbon Nanotube Hybrids: In Situ Formation on Bifunctional Catalysts and Their Superior Electrocatalytic Activity for Oxygen Evolution/Reduction Reaction. Small 2015, 10, 2251 2259. S5. Wang, J.; Wu, H.; Gao, D.; Miao, S.; Wang, G.; Bao, X. High-density Iron Nanoparticles Encapsulated within Nitrogen-doped Carbon Nanoshell as Efficient Oxygen Electrocatalyst for Zinc Air Battery. Nano Energy 2015, 13, 387 396. S6. Zhao, Y.; Kamiya, K.; Hashimoto, K.; Nakanishi, S. Efficient Bifunctional Fe/C/N Electrocatalysts for Oxygen Reduction and Evolution Reaction. J. Phys. Chem. C 2015, 119, 8
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