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Supporting Information A non-carbon catalyst support upgrades the intrinsic activity of ruthenium for hydrogen evolution electrocatalysis via strong interfacial electronic effectsXing Zhang, Rongjian Sa, Shuai Yang, Feng Zhou, Zheng Jiang,* Ruihu Wang*Experimental and computational sectionSynthesis of Ru-Mo2N MoO3 NRs was firstly prepared according to the literature method [S1]. MoO3 NRs (72 mg) was dispersed in ethanol (50 mL) by ultrasoniccation for 30 min. RuCl3 (0.1 mmol) and NH4HCO3 (2 mmol) were added and then the resultant mixture was stirred at ambient atmosphere for 6 h. The precipitate was collected by centrifugation and washed with ethonal for two times. The dried precipitate was loaded in a quartz boat and placed at the centre of a tube furnace. After flushed with high-purity N2, the tube furnace was heated from room temperature to 700 °C with a ramping rate of 10 °C min-1 and maintained at this temperature for 2 h. A 100 sccm NH3/Ar (10%/90%) flow was continuously vent through the quartz tube during the whole heating and cooling process. Synthesis of Ru/NC 300 mg of carbon black (Vulcan XC-72) was refluxed in 30 mL of nitric acid (70 wt%) at 120 °C for 1 h. The precipitate was collected by centrifugation and washed with water for three times. The final precipitate was dispersed in 10 mL of water and lyophilized to get the oxidized carbon black. The preparation procedures of Ru/NC were the same as that of Ru-Mo2N except that MoO3 NRs was replaced by the oxidized carbon black.Materials Characterization Transmission electron microscopy (TEM), high angle annular dark field scanning TEM (HAADF-STEM), energy dispersive X-ray spectroscopy (EDS), selective area electron diffraction (SAED) analyses were conducted on an FEI Tecnai G2 F30 microscope. Aberration-corrected scanning transmission electron microscopy characterizations were performed using a probe aberration corrected TEM microscope (JEOL JEM-ARM200CF). Powder X-ray diffraction (XRD) measurements were performed on a Rigaku MiniFlex 600 diffractometer using Cu Kα radiation. X-ray photoelectron spectroscopy (XPS) measurements were performed on a ESCALAB 250Xi spectrometer with a monochromatic Al Kα X-ray source. To minimize the random error from the XPS tests, all the XPS spectra were firstly calibrated by referring adventitious C 1s (C-C) peak at 284.6 eV. ICP-OES was performed on a Horiba Jobin Yvon Ultima2 spectrometer. The Brunauer-Emmett-Teller (BET) specific surface areas of the samples were measured by using a Micromeritics ASAP 2020 HD88 instrument. XAFS measurements at Ru K-edge (22117 eV) in both transmission and fluorescence mode were performed at the BL14W1 in Shanghai Synchrotron Radiation Facility (SSRF) [S2]. The electron beam energy was 3.5 GeV and the stored current was 230 mA (top-up). A 38-pole wiggler with the maximum magnetic field of 1.2 T inserted in the straight section of the storage ring was used. XAFS data were collected using a fixed-exit double-crystal Si(311) monochromator. A Lytle detector was used to collect the fluorescence signal, and the energy was calibrated using Ru foil. The photon flux at the sample position was 2.6×1012 photons per second. The raw data analysis was performed using IFEFFIT software package according to the standard data analysis procedures [S3]. The spectra were calibrated, averaged, pre-edge background subtracted, and post-edge normalized using Athena program in IFEFFIT software package. The Fourier transformation of the k3-weighted EXAFS oscillations, k2·χ(k), from k space to R space was performed to obtain a radial distribution function. And data fitting was done by Artemis program in IFEFFIT.Electrochemical measurements The catalyst inks were prepared by dispersing catalysts (10 mg) into a mixture of 50 μl of 5 wt% Nafion and 950 μl of ethanol under sonication for 1 h. The catalyst electrodes were prepared by dropping 50 μl of catalyst ink onto a carbon fiber paper (AvCarb MGL190, Fuel Cell Store) to cover an area of 0.5 cm-2. All electrochemical tests were taken on a CHI 760E electrochemistry workstation with a coupled three-electrode system.?Saturated calomel electrode (SCE) coupled with a double?salt?bridge were used as the reference electrode. Saturated KCl solution in the external salt bridge has been frequently replenished for avoiding the corrosion of SCE. The calibration of SCE to RHE was performed in a standard three-electrode system (Fig. S18). High-purity graphite rod was used as the counter electrode. For all of the electrochemical measurements, the corresponding electrolytes were saturated with H2 by continuous purging with high-purity H2 (99.999%) during the entire measurement processes. All polarization curves were recorded at a scan rate of 5 mV s-1 unless being specifically indicated. All the potentials reported in this work were manually iR-corrected. Calculation details All DFT calculations were performed by Dmol3 package [S4, S5]. The exchange-correlation term was used for the generalized gradient approximation proposed by the Perdew, Burke and Ernzerhof [S6]. The double numeric quality basis set with polarization functions (DNP) was adopted [S4, S7, S8]. The numerical basis sets can minimize the basis-set superposition error [S9]. A Fermi smearing of 0.005 hartree was utilized. The tolerances of the energy, gradient and displacement convergence were 1 10-5 hartree, 4 10-3 hartree per ?, and 5 10-3 ?, respectively. Herein, the initial structure data was obtained from the bulk fcc γ-Mo2N and the lattice parameters were optimizedwith 6× 6 × 6 Monkhorst-Pack sampling schemes.Then the slab modeling the Mo2N(111) surface has eight layers and a (2 × √3) surface unit cell. The atoms in the bottom four layers were fixed at the corresponding bulk positions and the atoms in the topfour layers were allowed to relax. The Mo2N(100) surface was modeled with a four layer slab of the (3 × 3) surface unit. The atoms of bottom two layer were fiexed during geometry optimization. All the periodic slabs had a vacuum spacing of 15 ?. The surface Brillouin zone was sampled by a (4 × 4 × 2) grid for Mo2N(111) and Mo2N (100) surfaces. Free energy change was calculated by the following equation: ΔG = ΔE + ΔZPE – TΔS. ΔE is the difference between the energy of the adsorption state and separated parts, ΔZPE is the difference in zero-point energies, and ΔS is the change of entropy.Fig. S1. Calculated band structure (left) and DOS (right) of Mo2N.Fig. S2. Structural characterization of as-prepared MoO3 nanorods. (a, b) TEM images, (c) HAADF-STEM image and (d) XRD pattern.Fig. S3. Structural characterization of RuOx(OH)y/MoO3 nanorods. (a, b) TEM images, (c) HAADF-STEM image and EDS elemental maps. (d) XRD pattern.Fig. S4. High-resolution TEM image of Ru-Mo2N.Fig. S5. XPS survey spectrum of Ru-Mo2N.Fig. S6. Stuctural characterizations of Mo2N nanorods. (a-c) TEM images and (d) XRD pattern.Fig. S7. Least-squares curve-fitting of Ru-Mo2N EXAFS spectrum. ΔE0, inner potential correction; σ2, Debye Waller factor accounts for both thermal and structural disorders; R-factor indicates the goodness of the fit.Fig. S8. Calculated formation energies for Ru doping into cubic phase γ-Mo2N. The large formation energies suggest that Ru could not be stably doped into the γ-Mo2N lattice.Fig. S9. Morphological and structural characterizations of Ru/NC. (a-c) TEM images and (d) XRD pattern. Fig. S10. XPS characterization of as-prepared Ru/NC. (a) Survey spectrum. (b-d) High resolution spectra of Ru 3d, Ru 3p and N 1s.Fig. S11. Morphological and structural characterizations of commercial Ru/C. (a-c) TEM images and (d) XRD pattern.Fig. S12. Electrochemical impedence spectra of Ru-Mo2N, Ru/C and Ru/NC recorded at biased potential of -100 mV vs. RHE in (a) 0.5 M H2SO4 and (b) 1 M KOH. Fig. S13. (a, b) TEM images and (c) XRD patterns of Ru-Mo2N after galvanostatic tests at -100 mA cm-2 for 10 h in (a) 0.5 M H2SO4 and (b) 1 M KOH.Fig. S14. HRTEM images of Ru-Mo2N after galvanostatic tests at -100 mA cm-2 for 10 h in (a) 0.5 M H2SO4 and (b) 1 M KOH.Fig. S15. XPS spectra of of Ru-Mo2N after galvanostatic tests at -100 mA cm-2 for 10 h in 0.5 M H2SO4 and 1 M KOH. .Fig. S16. CV curves acquired in 0.5 M H2SO4 (blue line) and a Cu2+-containing electrolyte (pink line) with (a) pure CFP and (b) Mo2N/CFP electrodes. The CV curves in Cu2+-containing electrolyte only with one redox couple, which is attributed to Cu overpotential deposition/stripping. Thus, both CFP and Mo2N have negligible contribution to the Cu-UPD redox couple. Fig. S17. Cu-UPD and stripping results of Ru-Mo2N, Ru/C and Ru/NC. The CV tests are performed in 0.5 M H2SO4. The Cu-stripping tests are performed in a Cu2+-containing electrolyte (0.5 M H2SO4 + 5 mM CuSO4 + 0.1 M KCl). For acquiring the Cu-stripping polarized plots, the electrodes are firstly hold at 0.2 V (vs. RHE) for 200 s to form a Cu UPD layer on Ru surface and then scan from 0.2 to 0.95 V (vs. RHE). The scan rate is 10 mV s-1. During the polarization at 0.2 V (vs. RHE) for 200 s, a monolayer of Cu atoms were deposited on Ru surfaces [S10]. Then, subsequent potential scan to higher potentials results in oxidative stripping of the Cu monolayer. Therefore, copper stripping charge could be calculated by integration of the Cu-stripping peak (yellow shadow), which has been corrected by the background ruthenium electrochemistry. It is noted that the current-potential relationship could be converted to current-time relationship due to the scan rate is known. Fig. S18. Calibration of SCE and conversion to RHE in (a) 0.5 M H2SO4 and (b) 1 M KOH. The calibration of SCE reference electrode is performed in a standard three-electrode system with polished Pt plates as the working and counter electrodes, and a SCE as the reference electrode. Electrolytes are saturated with high purity H2. CV scans were run at a scan rate of 1 mV s-1. The average value of the two potentials at which the current crossed zero was taken to be the thermodynamic potential (vs. RHE) for the hydrogen electrode reactions. In 0.5 M H2SO4, the conversion to RHE scale is based on the relationship: ERHE = ESCE + 0.267 V. In 1 M KOH, the conversion to RHE scale is based on the relationship: ERHE = ESCE + 1.056 V. Table S1. A performance comparison of Ru-Mo2N to state-of-the-art HER electrocatalysts.CatalystElectrolyteη10(mV)Tafel Slope(mV dec-1)Mass Loading(mg cm-2)ReferenceRu-Mo2N0.5 M H2SO41 M KOH181628351.0This workRu@MWCNT0.5 M H2SO41 M KOH13172727N/ANat. Commun., 2020, 11, 1278.N-CoP2-3500.5 M H2SO43846N/ASci. Adv., 2020, 6, eaaw8113.SANi-PtNWs1 M KOH7060N/ANat. Catal., 2019, 2, 495-503.Co1/PCN0.5 M H2SO41 M KOH15189N/A520.5Nat. Catal., 2019, 2, 134-141.L-Ag0.5 M H2SO432310.2Nat. Catal., 2019, 2, 1107-1114.Ru-NC-7000.5 M H2SO41 M KOH291228140.2Nat. Commun., 2019, 10, 631.Pt SASs/AG0.5 M H2SO412297.1Energy Environ. Sci., 2019, 12, 1000-1007.EG-Pt/CoP-1.50.5 M H2SO42142.50.1Energy Environ. Sci., 2019, 12, 2298-2304.Ni-FeP/C0.5 M H2SO41 M KOH729554720.4Sci. Adv., 2019, 5, eaav6009.Ru@C2N0.5 M H2SO41 M KOH141730380.29Nat. Nanotechnol., 2018, 12, 441-446. Mo2TiC2Tx-PtSA0.5 M H2SO430301.0Nat. Catal., 2018, 1, 985-992.Li-Pd3P2S8 NDs0.5 M H2SO491290.23Nat. Catal., 2018, 1, 460-468.Pt-GT-10.5 M H2SO418N/AN/ANat. Energy, 2018, 3, 773-782.RuCoP0.5 M H2SO41 M KOH112331370.3Energy Environ. Sci., 2018, 11, 1819-1827.Ru@CN-0.160.5 M H2SO41 M KOH12632N/A53N/AEnergy Environ. Sci., 2018, 11, 800-806.PtRu@RFCS0.5 M H2SO42027N/AEnergy Environ. Sci., 2018, 11, 1232-1239.Pt@PCM0.5 M H2SO41 M KOH1051396574N/ASci. Adv., 2018, 4, eaao6657.PtNi-O/C1 M KOH4079N/AJ. Am. Chem. Soc., 2018, 140, 9046-9050.Ni@Ni2P-Ru0.5 M H2SO41 M KOH51313541N/AJ. Am. Chem. Soc., 2018, 140, 2731-2734.H-TaS20.5 M H2SO46037N/ANat. Energy, 2017, 2, 17127.WC@NPC0.5 M H2SO451490.21J. Am. Chem. Soc., 2017, 139, ?5285-5288.η10: Overpotentials at -10 mA cm-2.Supplementary ReferencesF.-X. Ma, H. B. Wu, B. Y. Xia, C.-Y. Xu, X. W. Lou, Angew. Chem. Int. Ed. 54 (2015) 15395-15399. H.-S. Yu, X.-J. Wei, J. Li, S. Gu, S. Zhang,?L. Wang,?J. Ma,?Li Li,?Q.?Gao,?R. Si,?F.?Sun,?Y.?Wang,?F.?Song,?H. Xu,?X.?Yu, Y.?Zou,?J. Wang, Z.?Jiang, Y. Huang, Nucl. Sci. Tech. 26 (2015) 050102.M. Newville, J. Synchrotron Rad. 8 (2001) 322-324.B. Delley, J. Chem. Phys. 92 (1990) 508-517.B. Delley, J. Chem. Phys. 113 (2000) 7756-7764.J. P. Perdew, K. Burke, M. Ernzerhof,?Phys. Rev. Lett. 77 (1996) 3865-3868.A. Bergner, M. Dolg, W. Kuchle, H. Stoll, H. Preuss, Mol. Phys. 80 (1993) 1431-1441.C. S. Lee, T. S. Hwang, Y. Wang, S. M. Peng, C. S. Hwang, J. Phys. Chem 100 (1996) 2934-2941.T. Lin, W. D. Zhang, J. Huang, C. He, J. Phys. Chem. B 109 (2005) 13755-13760. C. L. Green, A. Kucernak, J. Phys. Chem. B 106 (2002) 1036-1047. ................
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