Thermal Decomposition of CdS Nanowires Assisted by ZIF-67 to

Subscriber access provided by University of South Dakota

Article

Thermal Decomposition of CdS Nanowires Assisted by ZIF-67 to Induce the Formation of Co9S8-Based Carbon Nanomaterials with High Lithium-Storage Abilities Fan Wang, Kai Li, Xiao Wang, Junqi Li, Jing Pan, Jing Feng, kai liu, Shuyan Song, and Hongjie Zhang ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.8b01259 • Publication Date (Web): 07 Sep 2018 Downloaded from http://pubs.acs.org on September 9, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Energy Materials

Thermal

Decomposition

of

CdS

Nanowires

Assisted by ZIF-67 to Induce the Formation of Co9S8-Based Carbon Nanomaterials with High Lithium-Storage Abilities Fan Wang,† Kai Li,† Xiao Wang,† Junqi Li,† Jing Pan,† Jing Feng,† Kai Liu,† Shuyan Song*,† and Hongjie Zhang*,† †

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied

Chemistry, Chinese Academy of Sciences, Changchun, 130022 Jilin, China. KEYWORDS: Metal-organic frameworks, Co9S8/S, N co-doped carbon, anion diffusion, cation exchange, lithium-storage abilities.

ABSTRACT: A solid ion-exchange and diffusion method has been successfully developed to produce Co9S8/S, N co-doped carbon hybrids. CdS is chosen as a hard template and ZIF-67 plays the important role of a reducing agent as well as the carbon, nitrogen and cobalt sources. It should be noticed that the usage of CdS instead of S powder or organic S compounds can efficiently avoid the air pollution and simplify the synthetic steps. In the following test, the asobtained Co9S8/S, N co-doped carbon nanomaterial exhibits remarkable enhanced LIBperformance.

ACS Paragon Plus Environment

1

ACS Applied Energy Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 23

With the world’s growing population and economic expansion, the frequent use of energy sources ends in high energy-deficit.1-3 Thus, a large number of efforts are needed urgently to improve the potential of energy conversion. Metal-organic frameworks (MOFs) have been regarded as ideal sacrificial templates for their various polyfunctional organic ligands and metal ions.4-7 This flexibility is not only reflected by the complication of components in the final product, but also the simple control of annealing conditions to significantly influence the structure and composition of the as-obtained functional product. In an inert atmosphere, porous carbon-based nanostructures can be easily fabricated, while pure metal oxides hollow nanocages can also be obtained under oxygen atmosphere.8 A series of transition metal/transition metal oxides/carbon

hybrids

have

been

successfully synthesized,

such

as

nitrogen-doped

carbon@graphitic carbon,9 hollow rhombic dodecahedron,10 double-shelled nanohybrids, et al.11 These functional nanomaterials exhibited great potential in energy-related area. Therefore, the reasonable design of the component and the hybrid nanostructure should be the most important factor. Transition metal sulfides, which have a much higher capacity and enhanced safety, represent one of the promising candidates as anode materials.12-14 As one of the most promising material, cobalt sulfide exhibited a great electrochemical performance for different kinds of applications. Like supercapacitors,15-17 lithium-ion batteries,18 hydrogen evolution reactions,19 oxygen reduction reactions,20 and electrocatalytic water splitting.21 It has been proven that constructing hybrid materials was beneficial to the performance. It allows the access of Li-ions and can also minimize the charge transport limitation and the ion diffusion length. Until now, enormous achievements have been made for the fabrication of chalcogenides on the basis of MOFs. As successfully examples, amorphous CoS hollow polyhedra can be easily fabricated via a wet


2

Page 3 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


sulfidation process between ZIF-67 and thioacetamide in ethylene glycol solution.22 The synthesis is facile and environmentally friendly, however, the organic ligands (carbon source) are lost absolutely. Additional steps are required if CoS/C hybrids are the final target. On the other hand, an efficient solid method has been developed to produce CoS@PCP/CNTs by directly annealing ZIF-67 and S power at high temperature.23 The high performance of these 3D hollow polyhedral might owe to the synergistic effects. Such a technique is simple and easily scalable, however, some risks should also be noticed that excess S powders require professional care, otherwise, air pollution is unavoidable. Therefore, it is particularly urgent to design a facile and environmentally friendly means to synthesize hybrid architectures consisting of cobalt sulfide and porous carbonaceous matrix. Based on the previous reports, two common experimental phenomena have been concluded. First, the organic ligand in ZIF-67 has strong reducibility to react with divalent transition metal ions to form the corresponding metal. Second, the traditional sulfidation reaction is always based on two kinds of S sources: organic compounds containing sulfur and S powders (or H2S gases). Be much different from them, some kinds of transition metal sulfides (including CdS and ZnS) also have high S contents, but they are rarely used as the S source. Compared to the S powders, H2S gas and organic compounds containing sulfur, the decomposed products of the sulfides can be easily controlled and recycled. Thus, it provides a possibility for the green synthesis of some functional sulfides with special compositions and structures. Based on the above two points, a new synthetic route is applied by combining the merits of ZIF-67 and transition metal sulfides. In this manuscript, CdS is chosen as the source of sulfur, and ZIF-67 plays the important role of an ideal sacrificial template and reductant as well as the carbon, nitrogen and cobalt sources. Details of the synthetic methods for the Co9S8/S, N co-doped carbon nanomaterials are illustrated in


3


Page 4 of 23

Scheme 1. First, a solvothermal method was applied to obtain CdS NWs. Then, the uniform CdS NWs are immersed in methanol with the existence of cobalt ions and PVP. Subsequently, 2methylimidazolate methanol solution is injected into the above solution, and the structure of candied haws on a stick is obtained. Ultimately, anion diffusion and cation exchange reactions occur in a calcination process at 800 °C. Co9S8/S, N co-doped carbon nanomaterials consist entirely of elemental components except for Cd in the original material. Scheme 1. The synthetic procedure of Co9S8/S, N co-doped.

Results and discussion First of all, a solvothermal reaction between Cd-diethyldithiocarbamate precursors and ethylenediamine at 180 °C for 24 hours was used to obtain CdS nanowires (NWs).24 In Figure S1a, the X-ray diffraction (XRD) pattern matches well with the hexagonal phase of CdS (JCPDS No. 41-1049). The corresponding scanning electron microscopy (SEM) images are listed in Figure S1b, the structure is as the same as the previous report.24 Next, the above-obtained CdS NWs are dispersed in the methanol solution containing polyvinylpyrrolidone (PVP) and Co(NO3)2 6H2O followed by adding a methanol solution of 2-methylimidazole. Without any ●

post-treatment or fine kinetic controlling, an interesting color-evolution process in solution from


4

Page 5 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


yellow to brownish-red is observed, indicating the self-polymerization reaction is successfully happened to obtain CdS/ZIF-67. The morphology and composition of as-obtained CdS/ZIF-67 are investigated by multiple characterization techniques including SEM, XRD and thermogravimetric analysis (TGA). As shown in Figure S2a, uniform and monodisperse CdS-inserted polyhedral with a structure of candied haws on a stick are presented. The XRD pattern of is shown in Figure S2b. The solid CdS and ZIF-67 can be easily distinguished. To further get the structural information of CdS/ZIF-67, the TGA curves are used to illustrate the thermal behavior of CdS/ZIF-67. With the images shown in Figure S3, three stable intervals are obviously observed. First, the CdS/ZIF-67 kept stable at about 460 °C which was in accordance with pure ZIF-67.9 Then, a swift weight loss between 460 °C and 633 °C was detected, caused by the carbonization of the ZIF-67. Interestingly, there is another swift weight loss occurs with a further increase of temperature, the content of the final product is estimated to be ∼26 % by TG analysis. On the basis of the above analysis and the low melting point of Cd (765 °C), together with the previously reported reaction mechanisms of ZIF-67,10 the evaporation of Cd is assumed to lead to the swift weight loss. This result shows that the organic ligands of ZIF-67 have strong reducibility. Cd2+ can be effectively reduced to Cd metal vapor by the organic ligands and evaporates as the temperature increases. The evaporation of Cd metal vapor accelerates the releasing of free S atoms at the same time, which is a benefit to achieve both the sulfidation of Co2+ and the doping of S atoms in carbon materials. According to the TGA results, the CdS/ZIF-67 precursors were firstly annealed at 800 °C (named as CZ-800) in order to accelerate the self-evaporation of Cd. Fortunately, the actual experimental result matches as well as expected. With the typical SEM images shown in Figure 1a, the shape and size are similar to ZIF-67. However, the surface of CZ-800 becomes


5


Page 6 of 23

very rough, many particles could be found on it, and the numbers of nanowires inserted in the polyhedra are declining obviously, only a few nanowires can be seen. Furthermore, the XRD pattern of CZ-800 shown in Figure 1b matches well with the phase of Co9S8 (JCPDS No. 190364), the diffraction peaks of the CdS disappear while a broad peak at approximately 2θ = 26 ° appears, which is attributed to the C (002). To further get the structural information of the CZ-800, the nanostructure is analyzed by TEM technology. In Figure 1c, many nanoparticles with sizes of ~15 nm can be easily distinguished on the surfaces. The magnified TEM images in Figure 1d and 1e confirm that these nanoparticles are homogenously embedded in the polyhedral framework. The obviously observed lattice spacing in Figure 1e matched well with Co9S8 (111) of 0.573 nm. These results suggest the successful releasing of S atoms from CdS nanowires. Interestingly, although the results of XRD patterns confirm the complete removal of CdS，the 1D nanostructure originally belonged to the CdS nanowires still exist in the system. The only difference is that the smooth nanowires are replaced by the typical 1D core@shell nanostructures. The thickness of the shell is about 3.75 nm (Figure 1g and 1h). A void space and some nanoparticles wrapped in the 1D nanostructure can be easily distinguished. The local energy dispersive X-ray spectroscopy (EDX) analysis in figure 1f indicates that there are only four kinds of elements in the 1D nanowire. These are C, N, S, Co element. No signals of Cd can be detected. Besides, the obviously observed lattice spacing in Figure 1i well agreed with Co9S8 (222) of 0.285 nm. This further indicates the effective cation exchange between Cd and Co at high temperature.


6

Page 7 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 1. a. SEM, b. XRD, c-e and g-i. TEM, f. EDX, j-n. STEM-EDS elemental maps of CZ800. Scanning transmission electron microscopy-mapping technology is then taken to obtain the element distributions. With the images shown in Figure 1j to 1n, the Co and S signals are stronger than that of C and N. Besides, the distribution of Co and S has a slight difference compared with C and N, which indicates the successful synthesizing of Co9S8/S, N co-doped carbon. We also investigate the elemental distribution of the 1D nanostructure. Along the 1D nanostructure, Co and S distribute intermittently, clearly showing the intervals between two Co9S8 nanoparticles, whereas C and N distribute uniformly on the whole 1D nanostructure. The


7


Page 8 of 23

phenomenon further indicates the formation of a Co9S8@C 1D nanostructure. Besides, the signal of Cd element cannot be detected anymore. TGA is then used to get the amount of Co9S8 in CZ800. Based on the TGA results in Figure S4, the Co9S8 content is calculated to be 60 wt.%。 Considering the above experimental results, we supposed that four separated conversion reactions existed in the annealing treatment simultaneity: (i)

ZIF-67 → Co2+ + N-doped C + Co;

(ii) CdS+ N-doped C→Cd↑+ free S↑； (iii) Co2+ + CdS + N-doped C→Co9S8 + Cd↑+ S, N co-doped C; (iv) Co + S → Co9S8. At the first stage, ZIF-67 is carbonized to Co nanoparticles, Co2+ and N-doped carbon. With the increase of the annealing temperature, CdS is reduced by N-doped carbon to Cd metal and Cd evaporates until the temperature is higher than a specific temperature. Meanwhile, the S atom is released. Third, parts of Co2+ transfer and react with CdS to produce Co9S8 nanoparticles in the original CdS position. During the diffusion process of S atoms, some S atoms dope into Ndoped carbon polyhedra, others react with Co nanoparticles to produce Co9S8 nanoparticles in situ. As a result, the unique structures are successfully obtained. In a short summary, two important achievements of our synthesis should be noticed: (1) most of the importance, the whole synthesis is in progress on the basis of a corporation of anion diffusion and cation exchange, no harmful exhaust gas is needed or generated. Cd metal, regarded as the only byproduct, can be easily collected, indicating the synthesis is indeed environmentally friendly. (2) The unique structure of Co9S8 nanoparticles wrapped by the carbon nanotubes in the original


8

Page 9 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


CdS position indicates CdS serves as the source of sulfur and ZIF-67 plays the important role of an ideal sacrificial template and reductant as well as the carbon, nitrogen and cobalt sources and the transferring of C, Co2+, S coexist in this system. To observe the effects of annealing temperatures on CdS/ZIF-67, 700 °C, and 900 °C are chosen as the other two annealing temperatures. The two samples are named CZ-700 and CZ900. With the typical SEM images shown in Figure S5a, the CZ-700 has shown the similar diameters with the original CdS/ZIF-67. The corresponding XRD data in Figure S6 confirms that a large number of CdS exist in CZ-700, which are in accordance with the SEM results. Meanwhile, we find that the specific diffraction peaks of Co9S8 also exist in Figure S6. That means after the Cd2+ was reduced to Cd metal, the redox between Co and S can be successfully induced. Additional TEM images are also taken and shown in Figure 2. It can be concluded that Co9S8 nanoparticles exist in both the polyhedra and the nanowire. Figure 2e well agrees with that of Co9S8 (220) of 0.342 nm and Co9S8 (222) of 0.285 nm, while Figure 2f well agrees with that of Co9S8 (220) of 0.342 nm and CdS (110) of 0.205 nm. For CZ-900, the SEM image and XRD pattern are similar to CZ-800. (Figure S5 and S6) With the typical TEM images of CZ-900 shown in Figure 2, the nanoparticles on CZ-900 aggregated. Void space can also be seen in the 1D nanostructure. The nanoparticles are confirmed to be Co9S8 by Figure 2g and 2h, which agree well with that of Co9S8 (222) of 0.285 nm. With the scanning transmission electron microscopyenergy dispersive spectrometer (STEM-EDS) images shown in Figure 2i and 2j, Cd element is indeed absent from CZ-700 to CZ-900. The distribution of Co and S in CZ-900 is similar to that of CZ-800, indicates the successful synthesizing of Co9S8/S, N co-doped carbon. The porosity and surface areas of these materials are explored by a nitrogen sorption technique (Figure S7).


9


Page 10 of 23

CZ-800 shows the biggest BET surface area (150.5 m2g−1) of all the investigated samples, compared with the CZ-700 (24.1 m2g−1) and CZ-900 (145.8 m2g−1).

Figure 2. Representative TEM, HRTEM, and STEM-EDS elemental maps of a, b, e, f, i: CZ-700; c, d, g, h, j: CZ-900. X-ray photoelectron spectroscopy (XPS) was then carried out to get more detailed analyses. The full spectrum of XPS shown in Figure S8 demonstrates that there was no presence of contamination from preparation precursors. As shown in Figure S9a, two major peaks at 795.1 and 779.86 eV correspond to Co 2p1/2 and Co 2p3/2.25-27 The C 1s spectrum for CZ-700, CZ-800 and CZ-900 shown in Figure S9b can be resolved into three major peaks, corresponding to C–C (C1, 284.5 eV), C=N (C2, 285 eV) and C–N (C3, 287 eV). We can conclude that N existed in the


10

Page 11 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


carbon. In Figure S9c, the N 1s spectra can be resolved into two peaks, corresponding to pyridinic-N (N1, 398.0 eV) and graphitic- N (N2, 401.3 eV), while S 2p can be divided into three different peaks at 162, 163.5, and 168 eV, corresponding to 2p3/2 and 2p1/2 peaks and –SOx-(x=24).28 Meanwhile, we got the C/N/S/Co ratio by the XPS results. Based on the results, the ratios of C/N/S/Co are 92.33/3.07/3.76/0.84 for CZ-700, 90.41/4.46/4.39/0.74 for CZ-800 and 90.82/2.51/6.05/0.63 for CZ-900. We then assemble the Co9S8/S, N co-doped carbon into Li half-cells. The typical CV curves of the Co9S8/S, N co-doped carbon composites for the initial six cycles are shown in Figure S10. A peak at about 1.3 V in the first cycle refers to the reduction of Co9S8 to metallic Co by the following reaction: Co9S8+16 Li+

9 Co+ 8 Li2S. The weak and wide peak at around 0.8 V

reflects the decomposition of the electrolyte and the formation of the solid electrolyte interface (SEI) layer on the surface of the Co9S8/S, N co-doped carbon composites. The peaks located at 1.94 and 2.36 V attribute to the conversion of metallic Co to Co9S8 and Li extraction process. In the subsequent five cycles, the peaks located at 1.94 V shift to 2.04V. The CV curves can be overlapped after the first cycle, indicating the highly reversible electrochemical reaction of the electrode materials. The galvanostatic discharge–charge (GDC) voltage profiles of CZ-800 at the current density of 0.05 A g−1 in a potential range of 0 – 3.0 V versus Li/Li+ for the 1st, 2nd, 3rd, 10th, 50th, and 80th cycles are presented in Figure 3a. The discharge plateau at about 1.3 V in the first cycle is caused by the reaction of Co9S8 + Li ↔ Li2S + Co.29 The subsequent cycles exhibit sloped profiles, in accordance with electrochemical processes of Li2S. The discharge and charge capacities of CZ-800 for the first cycle are 879.7 and 529.3 mA h g-1, which results in a reasonable CE of 60.17% (Figure 3b). We attribute the phenomenon to the irreversible formation of Li2O. It is very common for most anode materials.30-37 The discharge and charge


11


Page 12 of 23

capacities changed to 640.7 and 580.8 mA h g−1 during the second cycle, indicating a much lower capacity loss of ~9%. After a few cycles, the CE stabilizes at 98% quickly and after 80 cycles, the discharge capacity of CZ-800 increases gradually and reaches a value at 810 mA h g−1. Upon gradually increasing the current density, the GDC profiles of CZ-800 remain stable (Figure 3c). Besides, the rate capability is also an important parameter. In Figure 3d, the average specific capacities of CZ-800 are 719, 670, 649, 568, 493, 412 and 341 mA h g−1 at the current densities of 0.05, 0.1, 0.2, 0.5, 1, 2, 5 A g−1, respectively. After decreasing the current density back to 0.05 A g-1, the capacity of CZ-800 increases to 960 mA h g-1 quickly, disclosing a fine capacity recovery. For comparison, CZ-700 and CZ-900 were both assembled into Li half-cells. Figure S11 show cycling stability of the two electrodes at the current density of 0.05 A g-1. Capacities of 618.2 and 392.3 mA h g-1 are obtained for CZ-700 and CZ-900, respectively. As shown in Figure S12, CZ-800 shows the best performance and highest capacity retention among the three electrodes. The long-term cycles of the CZ-800 at 1 A g-1 are shown in Figure 3e. After 300 cycles, the reversible capacity keeps at a value of 500 mA h g-1. In a short summary, the high performance of CZ-800 can probably be ascribed into three reasons. First, the smaller Co9S8 nanoparticles contribute to the diffusion of Li-ions, significantly enhancing the rate of insertion/ extraction. Second, the void space within the 1D nanostructure can efficiently accommodate it to the volume change and accelerate the electrolyte into the polyhedral material. Third, the porous polyhedron serves as a good supporting material, maintaining the structural integrity and preventing particle aggregation.


12

Page 13 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. a) GDC profiles and b) cycling performance of CZ-800 at 0.05 A g-1. c) GDC profiles and d) cycling performance of CZ-800 at different current densities. e) Long-life cycling performance of CZ-800 at 1 A g-1. Experimental


13


Page 14 of 23

Preparation of CdS nanowires24: The uniform CdS NWs were obtained by a solvothermal reaction between Cd- diethyldithiocarbamate precursors and ethylenediamine at 180 °C for 24 hours. Synthesis of CdS/ZIF-67: The above-obtained CdS NWs (65 mg) are dispersed in the methanol solution containing polyvinylpyrrolidone (PVP, 175 mg) and Co(NO3)2 6H2O (498 mg) ●

followed by adding a methanol solution of 2-methylimidazole (765 mg). Being kept still for 24 h and without any post-treatment or fine kinetic controlling, an interesting color-evolution process in solution from yellow to brownish-red is observed, indicating the self-polymerization reaction is successfully happened to obtain CdS/ZIF-67. Finally, the obtained precipitate was collected by centrifugation, washed with methanol and dried at 60 °C for 12 h. Synthesis of CdS-Co9S8/S, N co-doped carbon, and Co9S8/S, N co-doped carbon: CdSCo9S8/S, N co-doped carbon was prepared by the carbonization of CdS/ZIF-67 in an inert atmosphere at 700 °C. The temperature of the oven was controlled at a certain speed. After reaching the target temperature, another three hours were needed. For the synthesis of Co9S8/S, N co-doped carbon, 800 °C, and 900 °C were chosen as the annealing temperature. The samples calcined at 700 °C, 800 °C and 900 °C were named CZ-700, CZ-800, and CZ-900. Materials characterization: A Rigaku-D/max 2500 V X-ray diffractometer with CuKα radiation (λ = 1.5418 Å), with an operation voltage and current maintained at 40 kV and 40 mA, was used to collect the X-ray diffraction patterns. A TECNAI G2 high-resolution transmission electron microscope operating at 200 kV was used to obtain the transmission electron microscopic images. TGA curves of the samples were acquired by using an SDT 2960 thermal analyzer at a heating rate of 10 °C• min–1 in air atmosphere within a temperature range of 10 to


14

Page 15 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1000 °C. X-ray photoelectron spectroscopy measurements were taken on an ESCALAB-MKII 250 photoelectron spectrometer (VG Co.) with AlKα X-ray radiation as the X-ray source for excitation. The gas adsorption was measured by a Micromeritics ASAP2020 surface area analyzer. Electrochemical measurements: Active material (80 wt%), acetylene black (10 wt%), and polyvinylidene fluoride (PVDF, 10 wt%) in N-methyl-2-pyrrolidone (NMP) were mixed together to prepare the electrodes. The slurries were uniformly spread onto a copper foil, drying at 80 °C in vacuum. The electrodes were then pressed and cut into disks followed by transferring into an argon-filled glove box. Coin cells were assembled in the laboratory using sodium metal as the counter electrode, Celgard 2400 membrane as the separator, and LiPF6 (1 M ) in ethylene carbonate/dimethyl carbonate (EC/DMC, 1:1 w/w) as the electrolyte. A Land Battery Measurement System (Land, PR China) was finally used to carry the Galvanostatic chargedischarge tests. Conclusions In all, we demonstrate a facile and environmentally friendly synthesis of Co9S8-based carbon via the combination of anion diffusion and cation exchange. Here, CdS serves as the source of sulfur, and ZIF-67 plays the important role of an ideal sacrificial template and reductant as well as the carbon, nitrogen and cobalt sources. It is found that the following annealing treatment can trigger the reduction of Cd2+ to Cd metal, and the releasing of S atoms at the same time. During the diffusion process of S atoms, some S atoms dope into N-doped carbon polyhedra, others react with Co nanoparticles to produce Co9S8 nanoparticles. Meanwhile, parts of Co2+ react with CdS to produce Co9S8 nanoparticles in the original CdS position. The result suggests the


15


Page 16 of 23

transferring process of Co2+. The benefit of our synthesis is in progress on the basis of a combination of anion diffusion and cation exchange, no harmful exhaust gas is needed or generated. Cd metal, the only by-product, can be easily collected, indicating the synthesis is indeed environmentally friendly. In the following tests, Co9S8-based carbon exhibits satisfied electrochemical performance in lithium-ion batteries, making it a promising anode material for LIBs. Such a strategy in the synthesis of hetero-elements doped carbon materials with the complex shape, combined anion diffusion with cation exchange, is of great significance for synthesizing highly efficient functional materials. Supporting Information. The following files are available free of charge. XRD, SEM, and TEM, etc. AUTHOR INFORMATION Corresponding Author *[email protected]; *[email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENT The authors are grateful for the financial aid from the National Natural Science Foundation of China (21590794, 21771173 and 21521092), Youth Innovation Promotion Association of Chinese Academy of Sciences (2011176), the project development plan of science and


16

Page 17 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


technology of Jilin Province (20180101179JC) and CAS-CSIRO project (GJHZ1730). REFERENCES 1. Dai, L. Functionalization of Graphene for Efficient Energy Conversion and Storage. Acc. Chem. Res, 2013, 46, 31-42. 2. Simon, P., Gogotsi, Y. Capacitive Energy Storage in Nanostructured Carbon-Electrolyte Systems. Acc. Chem. Res, 2013, 46, 1094-1103. 3. David, L., Bhandavat, R., Singh, G. MoS2/Graphene Composite Paper for Sodium-Ion Battery Electrodes, ACS Nano, 2014, 8, 1759-1770. 4. Schaefer, Z. L., Gross, M. L., Hickner, M. A., Schaak, R. E. Uniform Hollow Carbon Shells: Nanostructured Graphitic Supports for Improved Oxygen-Reduction Catalysis, Angew. Chem., Int. Ed., 2010, 49, 7045-7048. 5. Hermes, S., Schroter, M. K., Schmid, R., Khodeir, L., Muhler, M., Tissler, A., Fischer, R. W., Fischer, R. A. Metal@MOF: Loading of Highly Porous Coordination Polymers Host Lattices by Metal Organic Chemical Vapor Deposition, Angew. Chem., Int. Ed., 2005, 44, 6237-6241. 6. Aijaz, A., Karkamkar, A., Choi, Y. J., Tsumori, N., Ronnebro, E., Autrey, T., Shioyama, H., Xu, Q. Immobilizing Highly Catalytically Active Pt Nanoparticles Inside the Pores of MetalOrganic Framework: A Double Solvents Approach, J. Am. Chem. Soc., 2012, 134, 13926-13929. 7. Chen, Y. Z., Zhou, Y. X., Wang, H., Lu, J., Uchida, T., Xu, Q., Yu, S. H., Jiang, H. L. Insights into the Mechanism of Cumene Peroxidation Using Supported Gold and Silver Nanoparticles, ACS Catal., 2015, 3, 2062-2071.


17


Page 18 of 23

8. Salunkhe, R. R., Tang, J., Kamachi, Y., Nakato, T., Kim, J. H., Yamauchi, Y. Asymmetric Supercapacitors Using 3D Nanoporous Carbon and Cobalt Oxide Electrodes Synthesized From ASingle Metal–Organic Framework, ACS Nano, 2015, 9, 6288-6296. 9. Tang, J., Salunkhe, R. R., Liu, J., Torad, N. L., Imura, M., Furukawa, S., Yamauchi, Y. Thermal Conversion of Core-Shell Metal-Organic Frameworks: A New Method for Selectively Functionalized Nanoporous Hybrid Carbon, J. Am. Chem. Soc., 2015, 137, 1572-1580. 10. Yang, J., Zhang, F. J., Lu, H. Y., Hong, X., Jiang, H. L., Wu, Y., Li, Y. D. Hollow Zn/Co ZIF Particles Derived from Core-Shell ZIF-67@ZIF-8 as Selective Catalyst for the SemiHydrogenation of Acetylene, Angew. Chem. Int. Ed., 2015, 54, 10889-10893. 11. Hu, H., Guan, B. Y., Xia, B. Y., Lou, X. W. Designed Formation of Co3O4/NiCo2O4 DoubleShelled Nanocages with Enhanced Pseudocapacitive and Electrocatalytic Properties, J. Am. Chem. Soc., 2015, 137, 5590-5595. 12. Rui, X. H., Tan, H. T., Yan, Q. Y. Nanostructured Metal Sulfides for Energy Storage. Nanoscale, 2014, 6, 9889-9924. 13. Xu, X. D., Liu, W., Kim, Y., Cho, J. Nanostructured Transition Metal Sulfides for Lithium Ion Batteries: Progress and Challenges. Nano Today, 2014, 9, 604-630. 14. Yu, X. Y., Yu, L., Shen, L. F., Song, X. H., Chen, H. Y., Lou, X. W. General Formation of MS (M = Ni, Cu, Mn) Box-In-Box Hollow Structures with Enhanced Pseudocapacitive Properties. Adv. Funct. Mater., 2014, 24, 7440-7446.


18

Page 19 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


15. Li, H., Gao, Y. H., Shao, Y. D., Su, Y. T., Wang, X. W. Vapor-Phase Atomic Layer Deposition of Co9S8 and Its Application for Supercapacitors. Nano Lett., 2015, 15, 6689-6695. 16. Rakhi, R. B., Alhebshi, N. A., Anjum, D. H., Alshareef, H. N. Nanostructured Cobalt Sulfide-on-fiber

with

Tunable

Morphology

as

Electrodes

for

Asymmetric

Hybrid

Supercapacitors. J. Mater. Chem. A, 2014, 2, 16190-16198. 17. Xu, J., Wang, Q. F., Wang, X. W., Xiang, Q. Y., Liang, B., Chen, D., Shen, G. Z. Flexible Asymmetric Supercapacitors Based Upon Co9S8 Nanorod//Co3O4@RuO2 Nanosheet Arrays on Carbon Cloth. ACS Nano, 2013, 7, 5453-5462. 18. Zhou, Y. L., Yan, D., Xu, H. Y., Liu, S., Yang, J., Qian, Y. T. Multiwalled Carbon Nanotube@a-C@Co9S8 Nanocomposites: A High-Capacity and Long-Life Anode Material for Advanced Lithium Ion Batteries. Nanoscale, 2015, 7, 3520-3525. 19. Feng, L. L., Li, G. D., Liu, Y., Wu, Y., Chen, H., Wang, Y., Zou, Y. C., Wang, D., Zou, X. Carbon-Armored Co9S8 Nanoparticles as All-pH Efficient and Durable H2-Evolving Electrocatalysts. ACS Appl. Mater. Interfaces, 2015, 7, 980-988. 20. Ganesan, P., Prabu, M., Sanetuntikul, J., Shanmugam, S. Cobalt Sulfide Nanoparticles Grown on Nitrogen and Sulfur Codoped Graphene Oxide: An Efficient Electrocatalyst for Oxygen Reduction and Evolution Reactions. ACS Catal., 2015, 5, 3625-3627. 21. Zhu, H., Zhang, J. F., Yanzhang, R. P., Du, M. L., Wang, Q. F., Gao, G. H., Wu, J. D., Wu, G. M., Zhang, M., Liu, B., Yao, J. M., Zhang, X. W. When Cubic Cobalt Sulfide Meets Layered Molybdenum Disulfide: A Core–Shell System Toward Synergetic Electrocatalytic Water Splitting. Adv. Mater., 2015, 27, 4752-4759.


19


Page 20 of 23

22. Jiang, Z., Lu, W. J., Li, Z. P., Ho, K. H., Li, X., Jiao, X. L., Chen, D. R. Synthesis of Amorphous Cobalt Sulfide Polyhedral Nanocages for High Performance Supercapacitors. J. Mater. Chem. A, 2014, 2, 8603-8606. 23. Wu, R. B., Wang, D. P., Rui, X. H., Liu, B., Zhou, K., Law, A. W. K., Yan, Q. Y., Wei, J., Chen, Z. In-situ Formation of Hollow Hybrids Composed of Cobalt Sulfides Embedded within Porous Carbon Polyhedra/Carbon Nanotubes for High-Performance Lithium-Ion Batteries, Adv. Mater., 2015, 27, 3038-3044. 24. Han, B., Liu, S. Q., Xu, Y. J., Tang, Z. R. 1D CdS Nanowire-2D BiVO4 Nanosheet Heterostructures Toward Photocatalytic Selective Fine-Chemical Synthesis, RSC Adv., 2015, 5, 16476-16483. 25. Wang, F., Li, W., Feng, X. L., Liu, D. P., Zhang, Y. Decoration of Pt on Cu/Co DoubleDoped CeO2 Nanospheres and Their Greatly Enhanced Catalytic Activity, Chem. Sci., 2016, 7, 1867-1873. 26. F. Wang, X. Wang, D. P. Liu, J. M. Zhen, J. Q. Li, H. J. Zhang, Investigation of ZnCo2O4–Pt Hybrids with Different Morphologies Towards Catalytic CO Oxidation. Dalton Trans., 2015, 44, 21124-21130. 27. F. Wang, X. Wang, D. P. Liu, J. M. Zhen, J. Q. Li, Y. H. Wang, H. J. Zhang, HighPerformance ZnCo2O4@CeO2 Core@Shell Microspheres for Catalytic CO Oxidation. ACS Appl. Mater. Interfaces, 2014, 6, 22216-22223.


20

Page 21 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


28. Ai, K. L., Liu, Y. L., Ruan, C. P., Lu, L. H., Lu, G. Q. Sp2 C-Dominant N-Doped Carbon Sub-Micrometer Spheres with A Tunable Size: A Versatile Platform for Highly Efficient Oxygen-Reduction Catalysts. Adv. Mater., 2013, 25, 998-1003. 29. Manzi, A., Simon, T., Sonnleitner, C., DÖblinger, M., Wyrwich, R., Stern, O., Stolarczyk, J. K., Feldmann, J. Light-Induced Cation Exchange for Copper Sulfide Based CO2 Reduction. J. Am. Chem. Soc., 2015, 137, 14007-14010. 30. Zhang, J. B., Chernomordik, B. D., Crisp, R. W., Kroupa, D. M., Luther, J. M., Miller, E. M., Gao, J. B., Beard, M. C. Preparation of Cd/Pb Chalcogenide Heterostructured Janus Particles via Controllable Cation Exchange, ACS Nano, 2015, 9, 7151-7163. 31. Aslam, M. K., Shah, S. S. A., Li, S., Chen, C. Kinetically Controlled Synthesis of MOF Nanostructures:

Single-Holed

Hollow

Core–Shell

ZnCoS@Co9S8/NC

for

Ultra-High

Performance Lithium-Ion Batteries, J. Mater. Chem. A, 2018, 6, 14083-14090. 32. Zeng, P. Y., Li, J. W., Ye, M., Zhuo, K. F., Fang, Z. In Situ Formation of Co9S8/N-C Hollow Nanospheres by Pyrolysis and Sulfurization of ZIF-67 for High-Performance Lithium-Ion Batteries, Chem. Eur. J., 2017, 23, 9517-9524. 33. Xia, H., Li, K., Guo, Y., Guo, J., Xu, Q., Zhang, J. CoS2 Nanodots Trapped within Graphitic Structured N-doped Carbon Spheres with Efficient Performances for Lithium Storage. J. Mater. Chem. A, 2018, 6, 7148-7154. 34. Yu, L., Yang, J. F., Lou, X. W. Formation of CoS2 Nanobubble Hollow Prisms for Highly Reversible Lithium Storage, Angew. Chem., Int. Ed., 2016, 55, 13422-13426.


21


Page 22 of 23

35. Zhang, J. T., Yu, L., Lou, X. W. Embedding CoS2 Nanoparticles in N-Doped Carbon Nanotube Hollow Frameworks for Enhanced Lithium Storage Properties, Nano Res., 2017, 10, 4298-4304. 36. Zhuang, G. L., Gao, Y. F., Zhou, X., Tao, X. Y., Luo, J. M., Gao, Y. J., Yan, Y. L., Gao, P. Y., Zhong, X., Wang, J. G. ZIF-67/COF-Derived Highly Dispersed Co3O4/N-Doped Porous Carbon with Excellent Performance for Oxygen Evolution Reaction and Li-ion Batteries, Chem. Eng. J., 2017, 330, 1255-1264. 37. Zhuang, G. L., Bai, J. Q., Tao, X. Y., Luo, J. M., Wang, X. D., Gao, Y. F., Zhong, X., Li, X. N., Wang, J. G. Synergistic Effect of S, N-co-Doped Mesoporous Carbon Materials with High Performance for Oxygen-Reduction Reaction and Li-ion Batteries, J. Mater. Chem. A, 2015, 3, 20244-20253.


22

Page 23 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Herein, a facile and environmentally friendly method has been reported to synthesize Co9S8/S, N co-doped carbon hybrids by a thermal decomposition of CdS nanowires assisted by ZIF-67. The synthesis is one-step and easily scalable with the combination of anion diffusion and cation exchange. No harmful raw material is needed during the whole synthesis. In the following applications, Co9S8/S, N co-doped carbon exhibits satisfied electrochemical performance in lithium-ion batteries.


23

Thermal Decomposition of CdS Nanowires Assisted by ZIF-67 to

Recommend Documents