Hydrogen-incorporated TiS2 Ultrathin Nanosheets
Supporting information for
Hydrogen-incorporated TiS2 Ultrathin Nanosheets with Ultrahigh Conductivity for Stamp-transferrable Electrodes Chenwen Lin§†, Xiaojiao Zhu§†, Jun Feng†, Changzheng Wu*†, Shuanglin Hu‡, Jing Peng†, Yuqiao Guo†, Lele Peng†, Jiyin Zhao†, Jianliu Huang†, Jinlong Yang†, Yi Xie*†
Table of contents S1. Structural information and density functional calculations for the TiS2 bulk and monolayer structures ..............................................................................2 S2. Formation mechanism of HTS graphene analogue .......................................3 S3. XPS spectrum of the as-prepared bulk TiS2 ..................................................5 S4. Raman spectra of different HTS assembled films. ........................................6 S5. Elemental analysis of the HTS graphene analogue by HRTEM and EELS. ...................................................................................................................................6 S6. Temperature-dependent resistivity of synthetic bulk TiS2 ...........................8 S7. SEM images of the surface morphology and cross section of the assembled HTS film. ..................................................................................................................8 S8. The evidence of the existence of S-H bond based on the FT-IR analysis and 1H solid-state MAS NMR spectra. .................................................................9 S9. Mechanical stability testing upon the as-assembled HTS films. ................10 S10. Transferring of HTS films onto arbitrary substrates ...............................11 References ..............................................................................................................11
S1
S1. Structural information and density functional calculations for the TiS2 bulk and monolayer structures 1T-TiS2 crystallizes in a classic layered CdI2 structure, which is composed of S-Ti-S stacking units with hexagonally close-packed layer of sulfur atoms and titanium atoms occupying the octahedral sites in between1. In the TiS2 structure, the in-plane bonding is the strong covalent bonding forming the 2D in plane atomic lattices; while the interaction force between the layers is rather weak by van der waals forces. In fact, the lattice constant a and b of the hexagonal TiS2 unit cell is 3.4073 Å but the (001) lattice plane distance between the layers is 5.6953 Å, giving the larger distance along the c axis. In a word, the structural information of TiS2 gives the practical feasibility to be exfoliated forming the ultrathin graphene-like materials. The electronic structure and the conductivity changes of TiS2 were studied with density functional theory (DFT) calculations. We used the periodic boundary condition plane wave basis-set code package VASP2. The electron-ion interaction was described by the projector augmented-wave (PAW) method.3 The main calculations were performed with DFT+U method of Dudarev et al.( the effective Hubbard U=4.2eV)4, and the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional 5for unit cell of 1T TiS2. The atomic positions and lattice parameters of bulk were relaxed with DFT-D2 method of Grimme to consider the van der Waals interaction between layers6. The energy cutoff was set to 500 eV. Gamma-centered Monkhorst-Pack k-points sampling method with grid point of 14 and 18 for in-plane direction were used for geometry relaxation and total energy calculations of unit cell, respectively. In the direction normal to the layer, 8 and 1 k-grid point were respectively used for bulk and monolayer models7. To model monolayer systems, the c parameter was set to 4 times c of bulk, the vacuum layer was thus around 20Å to diminish virtual interactions between images. The geometries were relaxed until residual atomic forces less than 0.01eV/Å, and then the total energies were calculated converged to 10-5 eV per unit cell. After getting the geometric and electronic properties, the semi-classic transport properties were calculated by code BoltzTrap, using relaxation time τ=0.8 × 10-14 s.8. As is shown in Figure S1, the calculation results revealed that the pristine bulk 1T TiS2 is a metal S2
Figure S1a; while for the monolayer of pristine TiS2, the PBE calculations give a semi-metal with a zero indirect band gap (Figure S1b).
(a)
(b)
(d)
(c)
Figure S1. (a) Side-viewed atomic structure of bulk crystals; (b)Atomic structure of 1T-TiS2 along c-axis, showing the notable two-dimensional structural; The band structure of (c) bulk TiS2 calculated with PBE functional based on bulk structure of (a), and (d) monolayer calculated with PBE functional based on the monolayer structure of (b).
S2. Formation mechanism of HTS graphene analogue The HyTiS2 graphene analogues were formed by two steps: (i) the formation of LixTiS2 by the insertion and reduction of bulk TiS2 by n-butyl lithium; (ii) following ultrasonic treatment of the LixTiS2 to form the final HyTiS2 graphene analogue. Formation of the intermediate product of LixTiS2: In this procedure, the n-butyl lithium acts as the S3
dual role as the reducing reagent and the provider of the insertion Li+ ions, with the following reaction: TiS2 (bulk) + n-Butyl-Li → LixTiS2 + octane In a typical synthesis procedure, the bulk TiS2 was put into hexane solution including the n-butyl lithium under the inert gas atmosphere, and then the whole reaction system were heated to 60 oC to maintain a given reaction temperature. After the reaction process, the final product was washed with hexane and ethanol several times to get rid of the residual n-butyl lithium and any other contaminants. The intermediate lithium-intercalated product of LixTiS2 can be obtained. The amount of x in LixTiS2 was verified by the inductive coupled plasma emission (ICP) spectrometer, which provides the ratios of Li/Ti. In our experiment, the analysis results of the three sample are as follows: (1)Li: 0.407μg/mL, Ti: 19.760μg/mL; (2) Li: 1.476μg/mL, Ti: 19.168μg/mL; (3)Li: 2.513μg/mL, Ti: 19.832μg/mL. According to the results, the value of x can be calculated to be 0.142, 0.531, 0.874, respectively, showing the obvious gradient Li concentration values as the reaction time elongated. After the following hydrolysis of intermediate LixTiS2 in the aqueous solution, the corresponding hydric TiS2 products with the gradually increasing hydrogen concentrations of 0.075, 0.292 and 0.515 in the form of ultrathin nanosheets were achieved. Exfoliation from LixTiS2 to HyTiS2 graphene analogue: The HyTiS2 graphene analogues were obtained by the hydrolysis of intermediate LixTiS2 in the aqueous solution. In such process, the incorporated lithium ions play the important roles in the efficient exfoliation into ultrathin graphene analogues, with the following reaction formula: LixTiS2+H2O → HyTiS2+LiOH For the LixTiS2, the insertion of Li+ ions into the TiS2 interlayer spaces would expand the interlayer distance, and thus weakens the van der Waals interactions between the layers. Moreover, the following one hour of ultrasonic treatment assisted the breaking of the weak interlayer van der Waals interactions, achieving the isolation of 2D ultrathin nanosheets.
S4
Figure S2.The exfoliation process: from Li-intercalated LixTiS2 to HyTiS2 nanosheets with assisted ultrasonic treatment.
S3. XPS spectrum of the as-prepared bulk TiS2
Figure S3. XPS spectrum of the selected as-prepared bulk TiS2, where the symmetric peaks of Ti 2p3/2 and Ti 2p1/2 located at 458.8 eV and 464.5 eV , could be obviously observed and no corresponding Ti 2p3/2 (456.1 eV) and Ti 2p1/2 (462.1eV) for Ti3+ can be recognized.
S5
S4. Raman spectra of different HTS assembled films.
Figure S4. The Raman spectra of three annealed films with different hydrogen contents. As shown in the Figure S4, two-prominent peaks corresponding to the in-plane Eg and out-plane A1g modes of 1T-TiS2 can be clearly seen in all three samples. Our as-obtained HTS films showed Eg and A1g peaks at around 233cm-1 and 332 cm-1 which match the reported 1T-TiS2 spectra, and there were no noticeable differences among them. The peak broadening can be partially attributed to the inhomogeneity of the samples.
S5. Elemental analysis of the HTS graphene analogue by HRTEM and EELS. (a)
S6
(b)
(c)
Ti
(e) A
S
(d)
(f) B
Figure S5. Elemental ingredients analysis of HTS graphene analogue by HRTEM: (a) EDX spectrum of a typical ultrathin nanosheet from (b), where the signals of Cu are generated from the Cu grids. (b-d) The typical HAADF-STEM (b) and (c, d) elemental mapping images of a single exfoliated HTS ultrathin nanosheet, where the elements of Ti (indicated by red color) and S (indicated by blue color) were homogenously spatial distributions in the entire nanosheet. Since the hydrogen atoms is invisible for HRTEM methods, all the elemental ingredient analyses confirm the product has the chemical formula of TiS2, and no other obvious contaminants can be found in the as-obtained products. (e-f) Electron energy lost spectra (EELS) of Li0.874TiS2 (e) and H0.515TiS2 (f), demonstrating the absence of Li in our HTS sample.
S7
S6 Temperature-dependent resistivity of synthetic bulk TiS2
Figure S6 Temperature-dependent resistivity of synthetic bulk TiS2 based on the solid-state reaction of titanium and sulfur powders, and the electrical resistivity of synthetic bulk TiS2 is measured to be about 1.91 ×10-4 Ω∙m at 298 K.
S7. SEM images of the surface morphology and cross section of the assembled HTS film. (a)
(b)
Figure S7. (a) Low-magnification SEM image of the surface of as-assembled HTS film; (b) Cross section of the as-assembled film from the HTS graphene analogue. S8
From Figure S7(a), one can clearly see the smooth surface morphology of the as-assembled HTS film, which is consisted of tightly compressed nanosheets; and the cross-section SEM image in Figure S7(b) unraveled the layer-by-layer structure of the assembled films, showing the high quality of the assembled HTS film.
S8. The evidence of the existence of S-H bond based on the FT-IR analysis and 1H solid-state MAS NMR spectra. The evidence of formation of S-H bonds in the HyTiS2 can be found in the FT-IR spectra of the assembled films. As is known, 1T-TiS2 is composed of S-Ti-S stacking units with hexagonally close-packed layer of sulfur atoms and titanium atoms occupying the octahedral sites in between, forming the S-Ti-S layered structures. In our case, the FT-IR results reveals that the incorporation of H only connected to the S atoms forming the S-H bonds without the structural changes of S-Ti-S lattices, and thus the electron injection into the S-Ti-S lattice framework occurs to enhance their conductivity. For the HTS sample, the slightest hydrogen can be revealed through the S-H bonding in the FT-IR spectra. We took advantage of the FT-IR to reveal the existence of S-H where the feature peaks indicating the S-H bonding is at about 2560 cm-1. In order to eliminate the influence of the O-H, we made the film annealed at 150 oC under the Ar atmosphere. As expected, all the three films made from 3 different precursors obtained at the different reaction time show the absorption around the 2515 cm-1 (Figure S8(a)), and the position shift from the standard wave number can be understood by the different local atomic environments of S atoms in the S-Ti-S framework. Therefore, the hydrogen atom in the HTS existed in the form of S-H bonding without any change of the S-Ti-S framework. The existence of forming S-H bonds were further verified by the 1H solid-state MAS NMR spectra of hydric TiS2 samples. In this case, we carefully kept all the experimental conditions constant, especially for the mass of HTS samples, for all the 1H solid-state MAS NMR tests. As shown in the S9
Figure S8(b), except the signals at 1.02 ppm arise from the background of employed motor9, the signals at 3.04 ppm can be assigned to the presence of S-H bond10 and no signals of hydroxyl group (around 7 ppm) can be found. Although the 1H solid-state MAS NMR couldn’t provide the exact hydrogen content in each sample, it clearly displays the rising trend with the increasing of y values in different HTS samples. Therefore, the hydrogen incorporation is in the form of the S-H bonding without changing the 1T TiS2 structure, donating exotic electrons to S-Ti-S framework and resulting in the exceptional conductance.
(b)
(a)
Figure S8. The evidence of the existence of S-H bond based on the FT-IR analysis and H1 solid-state MAS NMR spectra. (a) FT-IR spectra of the HTS assembled films with different hydrogen concentrations; (b) 1H solid-state MAS NMR spectra of the HTS samples.
S9. Mechanical stability testing upon the as-assembled HTS films.
Figure S9. The stable electrical conductivity under the tightly crumpled state of the HTS films on the PET substrate, showing the ultra-flexibility of the as-assembled HTS films (the film was covered with S10
another piece of PET to avoid the contact of the film itself when crumpled). As is shown, when the HTS graphene analogue films on a flexible PET was tightly crumpled up, it still forms a complete electrical circuit to light up the blue LED, showing the excellent mechanical stability of the HTS film.
S10. Transferring of HTS films onto arbitrary substrates
(a)
(c)
(b)
(d)
Figure S10. The HTS film could be readily transferred to arbitrary substrates, including quartz (a), silicon (b), PET (c) and glass (rightmost in d), and even can be transferred to metal substrates such as copper (leftmost in d) and nickel (middle in d). Of note, the transferred HTS film on PET shows its excellent flexibility.
References (1) Biener, M. M.; Biener, J.; Friend, C. M. J. Chem. Phys. 2005, 122, 034706-6. (2) Kresse, G.; Joubert, D. Phys. Rev. B 1999, 59, 1758-1775. (3) Blöchl, P. E. Phys. Rev. B 1994, 50, 17953-17979. (4) Dudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P. Phys. Rev. B 1998, 57, 1505-1509. (5) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996, 77, 3865-3868. (6) Grimme, S. J. Comp. Chem. 2006, 27, 1787-1799. (7) Monkhorst, H. J.; Pack, J. D. Phys. Rev. B 1976, 13, 5188-5192. (8) Madsen, G. K. H.; Singh, D. J. Comput. Phys. Commun. 2006, 175, 67-71. (9) Fang, J.; Shi, F.; Bu, J.; Ding, J.; Xu, S.; Bao, J.; Ma, Y.; Jiang, Z.; Zhang, W.; Gao, C.; Huang, W. J. Phys. Chem. C 2010, 114, 7940-7948. (10) Sardo, M.; Siegel, R.; Santos, S. M.; Rocha, J.; Gomes, J. R. B.; Mafra, L. The J.Phys. Chem. A 2012, 116, 6711-6719. S11
Hydrogen-incorporated TiS2 Ultrathin Nanosheets with Ultrahigh Conductivity for Stamp-transferrable Electrodes Chenwen Lin§†, Xiaojiao Zhu§†, Jun Feng†, Changzheng Wu*†, Shuanglin Hu‡, Jing Peng†, Yuqiao Guo†, Lele Peng†, Jiyin Zhao†, Jianliu Huang†, Jinlong Yang†, Yi Xie*†
Table of contents S1. Structural information and density functional calculations for the TiS2 bulk and monolayer structures ..............................................................................2 S2. Formation mechanism of HTS graphene analogue .......................................3 S3. XPS spectrum of the as-prepared bulk TiS2 ..................................................5 S4. Raman spectra of different HTS assembled films. ........................................6 S5. Elemental analysis of the HTS graphene analogue by HRTEM and EELS. ...................................................................................................................................6 S6. Temperature-dependent resistivity of synthetic bulk TiS2 ...........................8 S7. SEM images of the surface morphology and cross section of the assembled HTS film. ..................................................................................................................8 S8. The evidence of the existence of S-H bond based on the FT-IR analysis and 1H solid-state MAS NMR spectra. .................................................................9 S9. Mechanical stability testing upon the as-assembled HTS films. ................10 S10. Transferring of HTS films onto arbitrary substrates ...............................11 References ..............................................................................................................11
S1
S1. Structural information and density functional calculations for the TiS2 bulk and monolayer structures 1T-TiS2 crystallizes in a classic layered CdI2 structure, which is composed of S-Ti-S stacking units with hexagonally close-packed layer of sulfur atoms and titanium atoms occupying the octahedral sites in between1. In the TiS2 structure, the in-plane bonding is the strong covalent bonding forming the 2D in plane atomic lattices; while the interaction force between the layers is rather weak by van der waals forces. In fact, the lattice constant a and b of the hexagonal TiS2 unit cell is 3.4073 Å but the (001) lattice plane distance between the layers is 5.6953 Å, giving the larger distance along the c axis. In a word, the structural information of TiS2 gives the practical feasibility to be exfoliated forming the ultrathin graphene-like materials. The electronic structure and the conductivity changes of TiS2 were studied with density functional theory (DFT) calculations. We used the periodic boundary condition plane wave basis-set code package VASP2. The electron-ion interaction was described by the projector augmented-wave (PAW) method.3 The main calculations were performed with DFT+U method of Dudarev et al.( the effective Hubbard U=4.2eV)4, and the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional 5for unit cell of 1T TiS2. The atomic positions and lattice parameters of bulk were relaxed with DFT-D2 method of Grimme to consider the van der Waals interaction between layers6. The energy cutoff was set to 500 eV. Gamma-centered Monkhorst-Pack k-points sampling method with grid point of 14 and 18 for in-plane direction were used for geometry relaxation and total energy calculations of unit cell, respectively. In the direction normal to the layer, 8 and 1 k-grid point were respectively used for bulk and monolayer models7. To model monolayer systems, the c parameter was set to 4 times c of bulk, the vacuum layer was thus around 20Å to diminish virtual interactions between images. The geometries were relaxed until residual atomic forces less than 0.01eV/Å, and then the total energies were calculated converged to 10-5 eV per unit cell. After getting the geometric and electronic properties, the semi-classic transport properties were calculated by code BoltzTrap, using relaxation time τ=0.8 × 10-14 s.8. As is shown in Figure S1, the calculation results revealed that the pristine bulk 1T TiS2 is a metal S2
Figure S1a; while for the monolayer of pristine TiS2, the PBE calculations give a semi-metal with a zero indirect band gap (Figure S1b).
(a)
(b)
(d)
(c)
Figure S1. (a) Side-viewed atomic structure of bulk crystals; (b)Atomic structure of 1T-TiS2 along c-axis, showing the notable two-dimensional structural; The band structure of (c) bulk TiS2 calculated with PBE functional based on bulk structure of (a), and (d) monolayer calculated with PBE functional based on the monolayer structure of (b).
S2. Formation mechanism of HTS graphene analogue The HyTiS2 graphene analogues were formed by two steps: (i) the formation of LixTiS2 by the insertion and reduction of bulk TiS2 by n-butyl lithium; (ii) following ultrasonic treatment of the LixTiS2 to form the final HyTiS2 graphene analogue. Formation of the intermediate product of LixTiS2: In this procedure, the n-butyl lithium acts as the S3
dual role as the reducing reagent and the provider of the insertion Li+ ions, with the following reaction: TiS2 (bulk) + n-Butyl-Li → LixTiS2 + octane In a typical synthesis procedure, the bulk TiS2 was put into hexane solution including the n-butyl lithium under the inert gas atmosphere, and then the whole reaction system were heated to 60 oC to maintain a given reaction temperature. After the reaction process, the final product was washed with hexane and ethanol several times to get rid of the residual n-butyl lithium and any other contaminants. The intermediate lithium-intercalated product of LixTiS2 can be obtained. The amount of x in LixTiS2 was verified by the inductive coupled plasma emission (ICP) spectrometer, which provides the ratios of Li/Ti. In our experiment, the analysis results of the three sample are as follows: (1)Li: 0.407μg/mL, Ti: 19.760μg/mL; (2) Li: 1.476μg/mL, Ti: 19.168μg/mL; (3)Li: 2.513μg/mL, Ti: 19.832μg/mL. According to the results, the value of x can be calculated to be 0.142, 0.531, 0.874, respectively, showing the obvious gradient Li concentration values as the reaction time elongated. After the following hydrolysis of intermediate LixTiS2 in the aqueous solution, the corresponding hydric TiS2 products with the gradually increasing hydrogen concentrations of 0.075, 0.292 and 0.515 in the form of ultrathin nanosheets were achieved. Exfoliation from LixTiS2 to HyTiS2 graphene analogue: The HyTiS2 graphene analogues were obtained by the hydrolysis of intermediate LixTiS2 in the aqueous solution. In such process, the incorporated lithium ions play the important roles in the efficient exfoliation into ultrathin graphene analogues, with the following reaction formula: LixTiS2+H2O → HyTiS2+LiOH For the LixTiS2, the insertion of Li+ ions into the TiS2 interlayer spaces would expand the interlayer distance, and thus weakens the van der Waals interactions between the layers. Moreover, the following one hour of ultrasonic treatment assisted the breaking of the weak interlayer van der Waals interactions, achieving the isolation of 2D ultrathin nanosheets.
S4
Figure S2.The exfoliation process: from Li-intercalated LixTiS2 to HyTiS2 nanosheets with assisted ultrasonic treatment.
S3. XPS spectrum of the as-prepared bulk TiS2
Figure S3. XPS spectrum of the selected as-prepared bulk TiS2, where the symmetric peaks of Ti 2p3/2 and Ti 2p1/2 located at 458.8 eV and 464.5 eV , could be obviously observed and no corresponding Ti 2p3/2 (456.1 eV) and Ti 2p1/2 (462.1eV) for Ti3+ can be recognized.
S5
S4. Raman spectra of different HTS assembled films.
Figure S4. The Raman spectra of three annealed films with different hydrogen contents. As shown in the Figure S4, two-prominent peaks corresponding to the in-plane Eg and out-plane A1g modes of 1T-TiS2 can be clearly seen in all three samples. Our as-obtained HTS films showed Eg and A1g peaks at around 233cm-1 and 332 cm-1 which match the reported 1T-TiS2 spectra, and there were no noticeable differences among them. The peak broadening can be partially attributed to the inhomogeneity of the samples.
S5. Elemental analysis of the HTS graphene analogue by HRTEM and EELS. (a)
S6
(b)
(c)
Ti
(e) A
S
(d)
(f) B
Figure S5. Elemental ingredients analysis of HTS graphene analogue by HRTEM: (a) EDX spectrum of a typical ultrathin nanosheet from (b), where the signals of Cu are generated from the Cu grids. (b-d) The typical HAADF-STEM (b) and (c, d) elemental mapping images of a single exfoliated HTS ultrathin nanosheet, where the elements of Ti (indicated by red color) and S (indicated by blue color) were homogenously spatial distributions in the entire nanosheet. Since the hydrogen atoms is invisible for HRTEM methods, all the elemental ingredient analyses confirm the product has the chemical formula of TiS2, and no other obvious contaminants can be found in the as-obtained products. (e-f) Electron energy lost spectra (EELS) of Li0.874TiS2 (e) and H0.515TiS2 (f), demonstrating the absence of Li in our HTS sample.
S7
S6 Temperature-dependent resistivity of synthetic bulk TiS2
Figure S6 Temperature-dependent resistivity of synthetic bulk TiS2 based on the solid-state reaction of titanium and sulfur powders, and the electrical resistivity of synthetic bulk TiS2 is measured to be about 1.91 ×10-4 Ω∙m at 298 K.
S7. SEM images of the surface morphology and cross section of the assembled HTS film. (a)
(b)
Figure S7. (a) Low-magnification SEM image of the surface of as-assembled HTS film; (b) Cross section of the as-assembled film from the HTS graphene analogue. S8
From Figure S7(a), one can clearly see the smooth surface morphology of the as-assembled HTS film, which is consisted of tightly compressed nanosheets; and the cross-section SEM image in Figure S7(b) unraveled the layer-by-layer structure of the assembled films, showing the high quality of the assembled HTS film.
S8. The evidence of the existence of S-H bond based on the FT-IR analysis and 1H solid-state MAS NMR spectra. The evidence of formation of S-H bonds in the HyTiS2 can be found in the FT-IR spectra of the assembled films. As is known, 1T-TiS2 is composed of S-Ti-S stacking units with hexagonally close-packed layer of sulfur atoms and titanium atoms occupying the octahedral sites in between, forming the S-Ti-S layered structures. In our case, the FT-IR results reveals that the incorporation of H only connected to the S atoms forming the S-H bonds without the structural changes of S-Ti-S lattices, and thus the electron injection into the S-Ti-S lattice framework occurs to enhance their conductivity. For the HTS sample, the slightest hydrogen can be revealed through the S-H bonding in the FT-IR spectra. We took advantage of the FT-IR to reveal the existence of S-H where the feature peaks indicating the S-H bonding is at about 2560 cm-1. In order to eliminate the influence of the O-H, we made the film annealed at 150 oC under the Ar atmosphere. As expected, all the three films made from 3 different precursors obtained at the different reaction time show the absorption around the 2515 cm-1 (Figure S8(a)), and the position shift from the standard wave number can be understood by the different local atomic environments of S atoms in the S-Ti-S framework. Therefore, the hydrogen atom in the HTS existed in the form of S-H bonding without any change of the S-Ti-S framework. The existence of forming S-H bonds were further verified by the 1H solid-state MAS NMR spectra of hydric TiS2 samples. In this case, we carefully kept all the experimental conditions constant, especially for the mass of HTS samples, for all the 1H solid-state MAS NMR tests. As shown in the S9
Figure S8(b), except the signals at 1.02 ppm arise from the background of employed motor9, the signals at 3.04 ppm can be assigned to the presence of S-H bond10 and no signals of hydroxyl group (around 7 ppm) can be found. Although the 1H solid-state MAS NMR couldn’t provide the exact hydrogen content in each sample, it clearly displays the rising trend with the increasing of y values in different HTS samples. Therefore, the hydrogen incorporation is in the form of the S-H bonding without changing the 1T TiS2 structure, donating exotic electrons to S-Ti-S framework and resulting in the exceptional conductance.
(b)
(a)
Figure S8. The evidence of the existence of S-H bond based on the FT-IR analysis and H1 solid-state MAS NMR spectra. (a) FT-IR spectra of the HTS assembled films with different hydrogen concentrations; (b) 1H solid-state MAS NMR spectra of the HTS samples.
S9. Mechanical stability testing upon the as-assembled HTS films.
Figure S9. The stable electrical conductivity under the tightly crumpled state of the HTS films on the PET substrate, showing the ultra-flexibility of the as-assembled HTS films (the film was covered with S10
another piece of PET to avoid the contact of the film itself when crumpled). As is shown, when the HTS graphene analogue films on a flexible PET was tightly crumpled up, it still forms a complete electrical circuit to light up the blue LED, showing the excellent mechanical stability of the HTS film.
S10. Transferring of HTS films onto arbitrary substrates
(a)
(c)
(b)
(d)
Figure S10. The HTS film could be readily transferred to arbitrary substrates, including quartz (a), silicon (b), PET (c) and glass (rightmost in d), and even can be transferred to metal substrates such as copper (leftmost in d) and nickel (middle in d). Of note, the transferred HTS film on PET shows its excellent flexibility.
References (1) Biener, M. M.; Biener, J.; Friend, C. M. J. Chem. Phys. 2005, 122, 034706-6. (2) Kresse, G.; Joubert, D. Phys. Rev. B 1999, 59, 1758-1775. (3) Blöchl, P. E. Phys. Rev. B 1994, 50, 17953-17979. (4) Dudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P. Phys. Rev. B 1998, 57, 1505-1509. (5) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996, 77, 3865-3868. (6) Grimme, S. J. Comp. Chem. 2006, 27, 1787-1799. (7) Monkhorst, H. J.; Pack, J. D. Phys. Rev. B 1976, 13, 5188-5192. (8) Madsen, G. K. H.; Singh, D. J. Comput. Phys. Commun. 2006, 175, 67-71. (9) Fang, J.; Shi, F.; Bu, J.; Ding, J.; Xu, S.; Bao, J.; Ma, Y.; Jiang, Z.; Zhang, W.; Gao, C.; Huang, W. J. Phys. Chem. C 2010, 114, 7940-7948. (10) Sardo, M.; Siegel, R.; Santos, S. M.; Rocha, J.; Gomes, J. R. B.; Mafra, L. The J.Phys. Chem. A 2012, 116, 6711-6719. S11
