Supporting Information Revelation of the Excellent Intrinsic Activity of MoS2 NiS MoO3 Nanowires for Hydrogen Evolution Reaction in Alkaline Medium Chuanqin Wang a,b, Bin Tian b, Mei Wu b, Jiahai Wang *b a School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China b National Engineering Center for Colloid Materials, Shandong University, Jinan 250100, China E-mail: jiahai_wang@sdu.edu.cn Tel: +86-15665709672 http://nanopore.weebly.com Figure S1. TEM-EDS spectrum of MoS 2 NiS MoO 3. Figure S2. SEM-EDS spectra of NiMoO 4 (A) and MoS 2 NiS MoO 3 (B). Figure S3. XRD pattern of NiS 2 MoS 2 @Ti-2 hetero-nanowires and MoS 2 NiS MoO 3 @Ti-1. Figure S4. Raman spectra of NiS (A), MoS 2 (B), NiMoO 4 (C). Figure S5. XPS spectrum (A) Mo 3d, (B) Ni 2p, (C) O 1s of NiMoO 4. S-1
Figure S6. (A) Linear sweep voltammograms of titanium substrate after different treatments. (B) Niquist plot obtained at -0.2 V vs. RHE in 1 M KOH. Ti foil treated in 1 M H 2 SO 4 for 2 h at 95 o C is defined as Ti-1; Ti foil treated in 1 M HCl for short time at room temperature is defined as Ti-2. Figure S7. (A) Linear sweep voltammograms of the NiMoO 4 on titanium substrate after different treatments (Ti foil treated in 1 M H 2 SO 4 for 2 h at 95 o C is defined as Ti-1; Ti foil treated in 1 M HCl for short time at room temperature is defined as Ti-2). (B) Niquist plot obtained at -0.2 V vs. RHE in 1 M KOH. Figure S8. Linear sweep voltammograms of MoS 2 NiS MoO 3 under different ph condition. Figure S9. (A) Typical SEM image of the MoS 2 NiS MoO 3 nanowires on Ti -1. (B) Typical SEM image of the NiS 2 -MoS 2 nanowires on Ti-2. (C) LSV of MoS 2 NiS MoO 3 nanowires on Ti -1. (D) LSV of the NiS 2 -MoS 2 nanowires on Ti -1. Ti-1 is obtained after deep polish. Figure S10. Typical SEM image of MoS 2 NiS MoO 3 before (A) and after 1000 CV (B). Table S1: Summary of HER activities of different materials. S-2
Figure S1 Element Weight% Atomic% O 6.88 19.83 S 28.95 41.67 Ni 24.95 19.62 Mo 39.22 18.88 S-3
Figure S2 A B Element Weight% Atomic% O 28.61 65.65 Ni 28.92 18.09 Mo 42.47 16.25 Element Weight% Atomic% O 11.77 28.38 Ni 22.95 15.08 Mo 27.46 11.04 S 37.82 45.5 S-4
Figure S3 Figure S4 To further verify the component of electrocatalyst, we performed the Raman measurement. The results show that the main composition of catalyst are MoS2 ( 374 and 405.6 cm -1 in Fig. S4B) and NiS (Fig. S4A). Moreover, Fig. S4C revealed the precursor of NiMoO4 nanowire has not been completely sulfurized. S-5
Figure S5 Figure S6 Current density (ma/cm 2 ) 0-20 -40-60 -80 A Ti-2 Ti-1 -Z''/ 250 200 150 100 50 B Ti-2 Ti-1-100 -0.9-0.8-0.7-0.6-0.5-0.4-0.3-0.2-0.1 Potential (V vs. RHE) Figure S7 0 0 100 200 300 Z'/ S-6
Figure S8 Figure S9 A 500 500 B 300 1 μm 1 μm Current density (ma/cm 2 ) 0-20 -40-60 -80 C 500 C Current density (ma/cm 2 ) 0-20 -40-60 -80 D 300 o C -100-0.25-0.20-0.15-0.10-0.05 0.00 Potential (V vs. RHE) -100-0.4-0.3-0.2-0.1 0.0 Figure S10 Potential (V vs. RHE) S-7
Table S1 Samples Onset potential [mv] Tafel slope [mv dec -1 ] Overpotential (mv) at 10 ma cm -2 MoP S (0.5 M H2SO4) -50 50 90 1 Ref. MoSe2/Mo Core Shell (0.5 M H2SO4) MoOx/MoS2 Core Shell (0.5 M H2SO4) NiS2 MoS2 nanoflakenanowires (1 M KOH) Core_shell MoO3-MoS2 Nanowires (0.5 M H2SO4) -89 34.7 166 2 N/A 63 259 3-76 70 110 4-200 50-60 250 5 MoS2/CoS2/CC (0.5 M H2SO4) N/A 73.4 87 6 NiMo3S4 hollow Nanoplates (0.1 M KOH) Co-Doped MoS2 (0.5 M H2SO4) Defect-Rich MoS2 (0.5 M H2SO4) -59 98 257 7 N/A 50 135 8-120 50 190 9 MoP@PC (0.5 M H2SO4) -77 66 153 10 MoS2 NiS MoO3 (1 M KOH) -36 54.5 91 This work References 1. Kibsgaard, J.; Jaramillo, T. F., Molybdenum Phosphosulfide: an Active, Acidstable, Earth-abundant Catalyst for the Hydrogen Evolution Reaction. Angew. Chem. Int. Ed. 2014,53 (52), 14433-14437. 2. Qu, Y.; Medina, H.; Wang, S. W.; Wang, Y. C.; Chen, C. W.; Su, T. Y.; Manikandan, A.; Wang, K.; Shih, Y. C.; Chang, J. W.; Kuo, H. C.; Lee, C. Y.; Lu, S. Y.; Shen, G.; Wang, Z. M.; Chueh, Y. L., Wafer Scale Phase-Engineered 1T- and 2H- MoSe2/Mo Core-Shell 3D-Hierarchical Nanostructures toward Efficient Electrocatalytic Hydrogen Evolution Reaction. Adv. Mater. 2016,28(44),9831 9838. 3. Jin, B.; Zhou, X.; Huang, L.; Licklederer, M.; Yang, M.; Schmuki, P., Aligned MoOx /MoS2 Core-Shell Nanotubular Structures with a High Density of Reactive S-8
Sites Based on Self-Ordered Anodic Molybdenum Oxide Nanotubes. Angew. Chem. Int. Ed. 2016,55 (40), 12252-12256. 4. An, T.; Wang, Y.; Tang, J.; Wei, W.; Cui, X.;Zhang, L.; Zheng, G., Interlaced NiS2 MoS2 Nanoflake-nanowires as Efficient Hydrogen Evolution Electrocatalysts in Basic Solutions. J. Mater. Chem. A 2016,4,13439 13443. 5. Chen, Z.; Cummins, D.; Reinecke, B. N.; Clark, E.; Sunkara, M. K.; Jaramillo, T. F., Core-shell MoO3-MoS2 Nanowires for Hydrogen Evolution: a Functional Design for Electrocatalytic Materials. Nano lett. 2011,11 (10), 4168-4175. 6. Huang, J.; Hou, D.; Zhou, Y.; Zhou, W.; Li, G.; Tang, Z.; Li, L.; Chen, S., MoS2 Nanosheet-coated CoS2 Nanowire Arrays on Carbon Cloth as Three- Dimensional Electrodes for Efficient Electrocatalytic Hydrogen Evolution. J. Mater. Chem. A 2015,3 (45), 22886-22891. 7. Jiang, J.; Gao, M.; Sheng, W.; Yan, Y., Hollow Chevrel-Phase NiMo3S4 for Hydrogen Evolution in Alkaline Electrolytes. Angew. Chem. Int. Ed.2016,55(49),15240-15245. 8. Dai, X.; Du, K.; Li, Z.; Liu, M.; Ma, Y.; Sun, H.; Zhang, X.; Yang, Y., Co- Doped MoS2 Nanosheets with the Dominant CoMoS Phase Coated on Carbon as an Excellent Electrocatalyst for Hydrogen Evolution. ACS Appl. Mat. Interfaces 2015,7 (49), 27242-27253. 9. Xie, J.; Zhang, H.; Li, S.; Wang, R.; Sun, X.; Zhou, M.; Zhou, J.; Lou, X. W.; Xie, Y., Defect-rich MoS2 Ultrathin Nanosheets with Additional Active Edge Sites for Enhanced Electrocatalytic Hydrogen Evolution. Angew. Chem. Int. Ed. 2013,25 (40), 5807-5813. 10. Yang, J.; Zhang, F.; Wang, X.; He, D.; Wu, G.; Yang, Q.; Hong, X.; Wu, Y.; Li, Y., Porous Molybdenum Phosphide Nano-Octahedrons Derived from Confined Phosphorization in UIO-66 for Efficient Hydrogen Evolution. Angew. Chem. Int. Ed.2016,55(41), 12854 12858. S-9