Effect of Spelt Wheat Flour and Kernel on Bread ... - ACS Publications

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( 2 0 1 6 ) 1 e9

Available online at www.sciencedirect.com

ScienceDirect journal homepage: www.elsevier.com/locate/he

Novel CoxSy/WS2 nanosheets supported on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction Xiao Shang a, Jing-Qi Chi a, Shan-Shan Lu a,b, Bin Dong a,b,*, Xiao Li a, Yan-Ru Liu a, Kai-Li Yan a, Wen-Kun Gao a,b, Yong-Ming Chai a, Chen-Guang Liu a,** a

State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580, PR China b College of Science, China University of Petroleum (East China), Qingdao 266580, PR China

article info

abstract

Article history:

To maximum the activity of transition metal sulfides for hydrogen evolution reaction

Received 9 August 2016

(HER), two strategies usually have been adopted including designing unique nano-

Received in revised form

structures and integrating other metal element. Herein, CoxSy/WS2 nanosheets supported

6 October 2016

on carbon cloth (CoxSy/WS2/CC) have been fabricated via a facile hydrothermal process.

Accepted 19 October 2016

The cross-linked structures composed of CoxSy/WS2 nanosheets uniformly cover on the

Available online xxx

surface of CC, which may expose abundant active sites for HER and accelerate charge

Keywords:

molar ratio of W/Co ¼ 1/3 (noted as CoxSy/WS2/CC-3) has been proved to have unique

CoxSy-incorporating

spherical CoxSy/WS2 nanostructure, which may further expose more active sites for HER.

WS2

Electrochemical measurements demonstrate that CoxSy-incorporating can enhance HER

Carbon cloth

activity and conductivity compared with WS2/CC. In addition, CoxSy/WS2/CC-3 exhibits the

Hydrothermal

best HER activity, smallest charge transfer resistance and excellent stability than the

transfer rate. The molar ratio of CoxSy-incorporating has been investigated in detail. The

Hydrogen evolution reaction

counterparts, implying that the degree of CoxSy-incorporating may impact the HER activity of WS2. The mechanisms of CoxSy-incorporating on enhancing HER activity of WS2 have been discussed. It may offer a promising way to design transition metal sulfides-based electrocatalysts for HER by non-precious metal incorporating. © 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Introduction Electrochemical water splitting to produce H2 and O2 has been acknowledged as efficient and clean route to provide sustainable hydrogen energy as an ideal energy carrier to replace fossil

fuels [1e5]. In recent years, continuous researches have been conducted to design effective non-precious metal-based materials for HER alternative to precious Pt-based catalysts [6e10]. Transition metal sulfides (TMDs) have emerged as attractive candidates and MoS2 has been regarded as representative one [8,11e13]. As a typical earth-abundant TMD material, WS2 is

* Corresponding author. State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580, PR China. Fax: þ86 532 86981787. ** Corresponding author. Fax: þ86 532 86981787. E-mail addresses: [email protected] (B. Dong), [email protected] (C.-G. Liu). http://dx.doi.org/10.1016/j.ijhydene.2016.10.109 0360-3199/© 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Shang X, et al., Novel CoxSy/WS2 nanosheets supported on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.10.109

2


also attractive as HER electrocatalyst [12,13]. However, the limited surface area with few active sites on edges, semiconductivity and aggregation of two dimensional (2D) materials can inhibit the further enhancement of HER activity of WS2. Currently, many researches have focused on tackling these issues of WS2, such as metallic nanosheets [14], nanoribbons [15], reduced graphene oxides hybrids [16] or N-incorporated nanosheets [17]. However, more novel strategies are still required. On basis of theoretical calculations over past few years, the chemical-inert basal plane of TMDs can be activated by metal doping [18e20]. It has been proved that Co doping in MoS2 can intrigue the intrinsic catalytic activity of MoS2 by generating more active sites as well as improving the conductivity of semi-conductive MoS2 [21e25]. However, few studies have ever focused on application of CoxSy-incorporating on WS2. Very recently, carbon cloth (CC) has been emerged as ideal substrate with excellent conductivity, good flexibility and chemical stability to satisfy harsh industrial conditions [26,27]. Particularly, the unique three-dimensional (3D) framework of CC cannot only provide abundant pathways for faster electron transfer process, but also contribute to better dispersion of active components and enhanced catalytic efficiency [28,29]. Therefore, it is promising to utilize CC as support to integrate 2D TMD materials and form hierarchical 3D electrodes for hydrogen production. Herein, we report that a facile hydrothermal synthesis has been used to prepare CoxSy-incorporated WS2 nanosheets supported on carbon cloth (CoxSy/WS2/CC). For comparison, the pure WS2 nanosheets based on CC (CoxSy/WS2/CC) has also been fabricated. XRD and XPS show the formation of CoxSy-incorporated WS2/CC. EDX spectra and HR-TEM image further confirm that the hybrid crystal of CoxSy has been successfully incorporated into WS2 nanosheets. CoxSy/WS2 nanosheets show cross-linked structure and uniformly cover on the surface of CC, which may avoid severe aggregation, facilitate charge transport and expose much more active sites for HER. The degree of CoxSy-incorporating has also been investigated by changing molar ratio of W/Co in precursor (low degree: 6/1, 3/1; middle degree 1/3; high degree: 1/6) and marked by CoxSy/WS2/CC-1, CoxSy/WS2/CC-2, CoxSy/WS2/CC3, CoxSy/WS2/CC-4. The middle degree of CoxSy-incorporating of CoxSy/WS2/CC-3 shows unique sphere-like structure of CoxSy/WS2 nanosheets, which may further enhance the surface area to provide more catalytic active sites for HER. Electrochemical measurements show that the HER performances of CoxSy/WS2/CC is better than that of WS2/CC, demonstrating that CoxSy-incorporating can intrigue the intrinsic HER activity and improve the conductivity of WS2. In addition, CoxSy/ WS2/CC-3 exhibits the best HER activity, smallest charge transfer impendence and excellent stability than other CoxSy/ WS2/CC, suggesting that the middle degree of CoxSy-incorporating may lead to maximum HER activity. The non-precious metal incorporating may offer a novel strategy to design TMD-based electrocatalysts for hydrogen production.

Experimental Prior to the typical experiment, carbon cloth (CC, thickness: 0.35 mm, surface density: 189 g m2) was treated in acid,

acetone and ethanol under sonication for 30 min consecutively. Then it was under hydrophilic treatment by concentrated nitric acid (20 mL) in a Teflon-lined stainless steel autoclave at 80 C for 6 h, followed by washing with water and dried at vacuum of 40 C. In a typical synthesis, oxalic acid (1.20 g), thioacetamide (1.80 g) and ammonium metatungstate (0.17 mg) were uniformly mixed with deionized water (30 mL). Then the solution was transferred to Teflon-lined stainless steel autoclave added with pre-treated CC and maintained at 200 C for 24 h. The final product were rinsed with water and dried in vacuum, which was marked by WS2/CC. In order to investigate the degree of CoxSyincorporating, cobalt acetate was added into the mixture by changing molar ratio of W/Co (low degree: 6/1, 3/1; middle degree 1/3; high degree: 1/6). The corresponding products were marked by CoxSy/WS2/CC-1, CoxSy/WS2/CC-2, CoxSy/WS2/CC-3, CoxSy/ WS2/CC-4, respectively. For comparison, the CoxSy/CC was also fabricated under the same condition without W precursor (ammonium metatungstate). The catalyst loading of CoxSy/WS2/ CC-1, CoxSy/WS2/CC-2, CoxSy/WS2/CC-3, CoxSy/WS2/CC-4, CoxSy/CC and WS2/CC is 12.8 mg/cm2, 15.3 mg/cm2, 13.6 mg/cm2, 3.9 mg/cm2, 1.1 mg/cm2 and 3 mg/cm2, respectively. X-ray diffraction (XRD, X'Pert PRO MPD, Cu KR) was conducted with 2q range from 5 to 70 . X-ray photoelectron spectrum (XPS, VG ESCALAB MK II, Al Ka of 1486.6 eV) was performed to identify the valence states of main elements of CoxSy/WS2/CC-3. Scanning electron microscopy (SEM, Hitachi, S-4800) was utilized to investigate the morphology of all samples. X-ray fluorescence elemental analysis (EDX) was undertaken on a representative area of the samples. Transmission electron microscopy (TEM, FEI Tecnai G2) and highresolution transmission electron microscopy (HR-TEM) were used to investigate the crystal structure of Co/WS2/CC-3. Electrochemical measurements were carried out in a standard three-electrode configuration (Gamry Reference 600 Instruments, USA). All as-synthesized samples were used as working electrodes, with platinum gauze as counter electrode and an Ag/AgCl as reference. 0.5 M H2SO4 was used as electrolyte (degassed by N2 in advance). Linear sweep voltammetry (LSV) was performed with a scan rate of 5 mV s1 (with iR correction). Electrochemical impedance spectroscopy (EIS) measurements were employed at 0.32 V (vs. Ag/AgCl) with frequency from 105 Hz to 102 Hz and an AC voltage of 5 mV. The long-term stability of CoxSy/WS2/CC-3 was evaluated by chronoamperometry under 0.34 V (vs. Ag/AgCl) in 104 s. The potentials conversion from vs. Ag/AgCl to vs. RHE is as follows:

pH (0.5 M H2SO4) ¼ 0.16

E (Ag/AgCl (saturated KCl)) vs. E (RHE) ¼ 0.197 V

E (vs. RHE) ¼ E (vs. Ag/AgCl) þ 0.197 V þ (0.0591 V) pH ¼ E (vs. SCE) þ 0.21V

Overpotential h ¼ E (vs. RHE) 1.23 V ¼ E (vs. SCE) 1.02 V

Please cite this article in press as: Shang X, et al., Novel CoxSy/WS2 nanosheets supported on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.10.109


3

Results and discussion Fig. S1 shows XRD of pure WS2/CC and CoxSy/CC. For WS2/CC, the peaks of (002), (004), (100), (102), (006), (105), (106), (110) can be indexed to WS2 (PDF no. 00-008-0237), revealing the high purity of product. From XRD curves of CoxSy/CC, the mixed crystal of CoxSy is composed of Co9S8 (PDF no. 03-065-6801), CoS2 (PDF no. 03-065-3322) and CoS (PDF no. 03-065-8977). Fig. 1a shows XRD data of all the CoxSy/WS2/CC samples. The identical peaks from WS2 can also be found in XRD of each CoxSy/WS2/CC sample. For low degree of CoxSy-incorporating in CoxSy/WS2/CC-1 and CoxSy/WS2/CC-2, the detection of (111) and (422) peaks can be from Co9S8, while the peak of (200) is from CoS2. With increasing of degree of CoxSy-incorporating in CoxSy/WS2/CC-3 and CoxSy/WS2/CC-4, CoS2 cannot be detected with new appearance of (100) facet from CoS. The changed hybrid crystal structure of CoxSy in CoxSy/WS2/CC suggests different HER activity for each electrocatalysts. The XPS data of CoxSy/WS2/CC-3 are shown in Fig. 1bed. In Fig. 1b, the peak of W4f is divided into W4f7/2 and W4f5/2. The peak at 33.2 eV and 34.8 eV can be assigned to W (IV) of WS2 [30,31]. Additionally, the peaks at 35.6 eV and 37.8 eV can be indexed to oxidation state of W (VI) in air [32,33]. The element of Co in Fig. 1c shows that Co2p is divided into Co2p3/2 (778.53 and 780.59 eV) and Co2p1/2 (793.71 and 797.63 eV) with two shakeup satellites (marked by “Sat.”) [34]. For S 2p in Fig. 1d, the peaks at 161.2 eV and 162.9 eV are from S 2p3/2 and S 2p1/2, respectively [34,35]. Fig. S2 shows SEM images of as-prepared WS2/CC, CoxSy/ CC, CoxSy/WS2/CC-1, CoxSy/WS2/CC-2 and CoxSy/WS2/CC-4. WS2/CC shows uniform WS2 film covering on CC in Fig. S2a-1, and under the higher magnification WS2 film is composed of nanosheets with random stacking in Fig. S2a-2. Figs. S2b-1 and S2b-2 also show random stacking of CoxSy nanosheets on CC. For CoxSy/WS2/CC-1 and CoxSy/WS2/CC-2 with low degree of CoxSy-incorporating (Figs. S2c-1 and S2d-1), the surface on CC of CoxSy/WS2/CC-1 and CoxSy/WS2/CC-2 are both covered by porous film with discontinuous fracture. The higher magnification of CoxSy/WS2/CC-1 and CoxSy/WS2/CC-2 (Figs. S2c-2 and S2d-2) shows enhanced morphology of crosslinked thin nanosheets compared with WS2/CC, probably caused by synergic effect between CoxSy and WS2. The crosslinked structure may provide large surface area to expose abundant active sites for HER. With increasing of CoxSyincorporating, SEM morphology of CoxSy/WS2/CC-3 is greatly changed in Fig. 2a, despite that the closer view (in Fig. 2b) of cross-linked thin nanosheets remains similar with CoxSy/ WS2/CC-1 and CoxSy/WS2/CC-2. It can be seen from Fig. 2a that many sphere-like clusters cover on the surface of CC, which may further enlarge the overall surface area for exposing more catalytic active sites for HER and facilitate the efficient contact between active sites and electrolyte. However, the higher degree of CoxSy-incorporating of CoxSy/WS2/CC-4 shows the over accumulation of clusters on the surface of CC Fig. 1 e (a) XRD patterns of all samples. XPS data of CoxSy/ WS2/CC-3: (b) W4f; (c) Co 2p; (d) S 2p. Please cite this article in press as: Shang X, et al., Novel CoxSy/WS2 nanosheets supported on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.10.109

4


Fig. 2 e (a, b) SEM images, (c) EDX spectra and (d) SEM mapping of CoxSy/WS2/CC-3. Please cite this article in press as: Shang X, et al., Novel CoxSy/WS2 nanosheets supported on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.10.109


(in Figs. S2e-1 and S2e-2), which may lead to less exposed active sites and inferior HER activity. In order to confirm the existence of incorporating element, EDX of CoxSy/WS2/CC-3 was conducted. Fig. 2c shows the existence and composition of W, Co, S and C element in CoxSy/ WS2/CC-3, which confirms the successful CoxSy-incorporating in CoxSy/WS2/CC-3. The elemental mappings in Fig. 2d also demonstrate the homogeneous distribution of W, Co, S elements. The well dispersion of all elements may illustrate the uniform CoxSy-incorporating. Similarly, SEM and elemental mapping of CoxSy/WS2/CC-1, CoxSy/WS2/CC-2 and CoxSy/WS2/ CC-4 are shown in Fig. S3, which display uniform distribution of W, Co, S elements and confirm the successful CoxSyincorporating in all samples of CoxSy/WS2/CC. In order to further study the crystal and morphology of CoxSy/WS2/CC-3, TEM and HR-TEM of CoxSy/WS2 nanosheets scraped off CoxSy/WS2/CC-3 are shown in Fig. 3. TEM image of Fig. 3a with HR-TEM image of Fig. 3b show the typical twodimensional layered structure, which is consistent with SEM morphology of thin CoxSy/WS2 nanosheets in Fig. 2b. The higher resolution image of Fig. 3c shows that fringe spacings of 0.618 nm, 0.573 nm and 0.292 nm can be indexed to facets of WS2 (002), Co9S8 (111) and CoS (100), respectively. The coexistence of WS2, Co9S8 and CoS in the same sample demonstrates the CoxSy-incorporating in CoxSy/WS2/CC-3. The HER activities of all the as-prepared samples are shown in Fig. 4. LSV curves in Fig. 4a shows that Pt/C shows the best HER activity with negligible onset potential. Both WS2/CC and CoxSy/CC behaves poorly for HER with large overpotential (280 mV and 320 mV, respectively). In contrast, all CoxSy/WS2/CC samples exhibit enhanced HER activity requiring much smaller overpotential of 180, 150, 95, 120 mV for CoxSy/WS2/CC-1, CoxSy/WS2/CC-2, CoxSy/WS2/CC-3, CoxSy/ WS2/CC-4, respectively. It illustrates that CoxSy-incorporating can significantly improve the HER activity of WS2. In addition, the degree of CoxSy-incorporating is another key in determining the enhancement of HER activity of WS2. Both increasing and decreasing CoxSy-incorporating can cause worse HER activity of WS2. Thus it can be concluded that the middle CoxSy-incorporating degree of CoxSy/WS2/CC-3 exhibits the best HER activity and only needs overpotential of 120 mV to drive 10 mA cm2. The corresponding Tafel plots (Fig. 4b) shows that CoxSy/WS2/CC-3 possesses the smallest value of Tafel slope (89 mV dec1), implying fastest kinetics of hydrogen evolution. The further insight of kinetics for HER can be investigated by EIS data in Fig. 4c. By fitting an equivalent circuit inserted in Fig. 4c, the values of charge transfer resistance of all samples are shown Table 1. It can be seen that all charge transfer resistance (Rct) value of all CoxSy/WS2/CC samples are much smaller than that of WS2/CC (161.00 U) and CoxSy/CC (60.08 U), indicating the improved conductivity of CoxSy/WS2/CC owing to the incorporation of CoxSy. It reveals that the excellent conductivity of CoxSy can improve the semiconducting properties of WS2 and further facilitate charge transfer process for HER. Obviously, CoxSy/WS2/CC-3 has the smallest Rct of 6.61 U, suggesting the efficient Faradic process and superior HER kinetics. The HER performance of all samples have been estimated by electrochemically active surface areas (ECSA), which can be measured by double-layer capacitance (Cdl) from CV results

5

Fig. 3 e (a) TEM image and (b, c) HR-TEM images of CoxSy/ WS2/CC-3.


6


Fig. 4 e Electrochemical measurements results for all samples. (a) Linear sweep voltammogram curves; (b) Tafel plots; (c) Electrochemical impedance spectroscopy (EIS) results; (d) Determined double-layer capacitance (Cdl); (e) Polarization curves normalized by active sites and expressed in terms of TOF; (f) stability test by chronoamperometry.


7


(Fig. S4). As shown in Fig. 4d and Table 2, the values of Cdl for CoxSy/WS2/CC-1, CoxSy/WS2/CC-2, CoxSy/WS2/CC-3, CoxSy/ WS2/CC-4, WS2/CC and CoxSy/CC are calculated to be 34.4, 42.3, 87.1, 31.8, 27.7 and 2.8 mF cm2, respectively. Compared with WS2/CC and CoxSy/CC, the enhanced value of Cdl for CoxSy/WS2/ CC illustrates higher exposure of electrocatalytic active sites for HER. It suggests that the incorporated CoxSy may intrigue the intrinsic HER activity of WS2 by synergistic effect between CoxSy and WS2. In addition, exchange current densities of all samples are also obtained by the extrapolation of Tafel plots, as shown in Table 3. It shows that CoxSy/WS2/CC-3 has the largest exchange current density among all counter parts, indicating the fastest electron transfer and the best HER performance. The turnover frequency (TOF) is another important factor to determine the intrinsic per-site activity of the electrocatalysts. On basis of calculation method of TOF (shown in supporting information), the number of active sites of all samples are estimated by CVs (Fig. S5), as displayed in Table 3. It shows that each CoxSy/WS2/CC can expose more active sites for HER than that of WS2/CC and CoxSy/CC, suggesting that the incorporated CoxSy can intrigue the intrinsic HER activity of WS2. Fig. 4e shows the polarization curves normalized by the number of active sites and expressed in terms of TOF. It can be seen that the value of TOF for CoxSy/WS2/CC-3 for each active site is 0.01 s1 at the lowest overpotential of 83 mV than the

counterparts, which demonstrating the advantage of the middle degree of CoxSy-incorporating. The long-term stability of CoxSy/WS2/CC-3 has been evaluated by chronoamperometry test, as shown in Fig. 4f. It shows that the current density of CoxSy/WS2/CC-3 remains nearly unchangeable in 104 s test, exhibiting excellent stability in HER process. It suggests that carbon cloth as substrate may intensely integrate the active components on the surface, which can ensure the stability of active components in longterm water electrolysis. In order to further study the structure stability of CoxSy/ WS2/CC-3, XRD and SEM after stability test are shown in Fig. 5. XRD data in Fig. 5a shows that there are no obvious changes

Table 1 e Elemental values of fitted equivalent circuit based on EIS spectra for HER. Samples

Rs/U

Rct/U

CoxSy-WS2/CC-1 CoxSy-WS2/CC-2 CoxSy-WS2/CC-3 CoxSy-WS2/CC-4 CoxSy/CC WS2/CC

1.87 0.66 2.29 2.59 1.51 2.05

17.86 9.17 6.61 9.66 60.08 161.00

Table 2 e The calculation results of ECSA and RF of all samples for HER. Sample

Cdl mF

CoxSy/WS2/CC-1 CoxSy/WS2/CC-2 CoxSy/WS2/CC-3 CoxSy/WS2/CC-4 CoxSy/CC WS2/CC

68.80 84.60 174.20 63.60 5.60 55.40

Cs mF cm

2

0.035 0.035 0.035 0.035 0.035 0.035

ECSA, cm2

GSA, cm2

RF

1965.71 2417.14 4977.14 1817.14 160.00 1582.86

2.00 2.00 2.00 2.00 2.00 2.00

982.86 1208.57 2488.57 908.57 80.00 791.43

Fig. 5 e (a) XRD patterns of CoxSy/WS2/CC-3 before and after stability test. (b) SEM image of CoxSy/WS2/CC-3 after chronoamperometry test.

Table 3 e The calculated TOF of all samples for HER. Samples CoxSy/WS2/CC-1 CoxSy/WS2/CC-2 CoxSy/WS2/CC-3 CoxSy/WS2/CC-4 CoxSy/CC WS2/CC

Onset potential (V vs. RHE)

Exchange current densities (mA cm2)

Overpotential (h, mV) at j ¼ 20 mA cm2

Number of active sites 104

TOF (s1) at h ¼ 200 mV

180 120 95 113 320 280

5.6234 6.3096 6.4938 4.2170 0.4216 0.7450

153 135 119 142 452 351

0.64 1.25 1.79 1.66 0.25 0.26

0.0041 0.0030 0.0044 0.0033 0.0008 0.0028


8


among all the peaks before and after chronoamperometry test, indicating that the crystal structure of active components in CoxSy/WS2/CC-3 can be maintained well in long time of hydrogen production. The morphology of CoxSy/WS2/CC-3 after stability test in SEM image (Fig. 5b) also confirm that the cross-linked nanosheets remains unchangeable with negligible aggregation, which can still provide large surface area with abundant exposure of active sites for HER.

Conclusions CoxSy-incorporated WS2 nanosheets loaded on carbon cloth (CoxSy/WS2/CC) has been fabricated via a facile hydrothermal process. EDX spectra and HR-TEM prove the successful incorporation of hybrid crystal of CoxSy into WS2 nanosheets. SEM images shows the cross-linked structure of CoxSy/WS2 nanosheets uniformly covering on the surface of CC, which are favorable for rapid charge transfer and exposure of abundant active sites for HER. More importantly, the degree of CoxSy-incorporating has been systematically investigated. The electrochemical measurements demonstrate that CoxSyincorporating can enhance the HER activity of CoxSy/WS2/CC and lower the charge impendence than that of WS2/CC. The middle degree of CoxSy-incorporating (CoxSy/WS2/CC-3) exhibits the best HER activity, smallest charge transfer impendence and excellent stability than other CoxSy/WS2/CC, suggesting that the middle degree of CoxSy-incorporating may lead to maximum HER activity. It may offer a novel strategy to design 2D TMD-based electrocatalysts for HER by nonprecious metal incorporating.

Acknowledgements This work is financially supported by the National Natural Science Foundation of China (U1162203 and 21106185) and the Fundamental Research Funds for the Central Universities (15CX05031A) and Postgraduate Innovation Project of China University of Petroleum (YCXJ2016044).

Appendix A. Supplementary data Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.ijhydene.2016.10.109.

references

[1] Xia BY, Yan Y, Li N, Wu HB, Lou XWD, Wang X. A metaleorganic framework-derived bifunctional oxygen electrocatalyst. Nat Energy 2016;1:15006e14. [2] Li H, Tang Q, He B, Yang P. Robust electrocatalysts from an alloyed PteRueM (M¼ Cr, Fe, Co, Ni, Mo)-decorated Ti mesh for hydrogen evolution by seawater splitting. J Mater Chem A 2016;4:6513e20.

[3] Niu X, Tang Q, He B, Yang P. Robust and stable ruthenium alloy electrocatalysts for hydrogen evolution by seawater splitting. Electrochim Acta 2016;208:180e7. [4] Luo Q, Peng M, Sun X, Luo Y, Asiri AM. Efficient electrochemical water splitting catalyzed by electrodeposited NiFe nanosheets film. Inter J Hydrogen Energy 2016;41:8785e92. [5] Shang X, Hu W-H, Han G-Q, Liu Z-Z, Dong B, Liu Y-R, et al. Crystalline phase-function relationship of in situ growth NixSy controlled by sulfuration degree for oxygen evolution reaction. Inter J Hydrogen Energy 2016;41:13031e8. [6] Jiang P, Liu Q, Liang Y, Tian J, Asiri AM, Sun X. A costeffective 3D hydrogen evolution cathode with high catalytic activity: FeP nanowire array as the active phase. Angew Chem Inter Ed 2014;53:12855e9. [7] Tian J, Cheng N, Liu Q, Sun X, He Y, Asiri AM. Self-supported NiMo hollow nanorod array: an efficient 3D bifunctional catalytic electrode for overall water splitting. J Mater Chem A 2015;3:20056e9. [8] Xie J, Zhang H, Li S, Wang R, Sun X, Zhou M, et al. Defect-rich MoS2 ultrathin nanosheets with additional active edge sites for enhanced electrocatalytic hydrogen evolution. Adv Mater 2013;25:5807e13. [9] Liu T, Sun X, Asiri AM, He Y. One-step electrodeposition of NieCoeS nanosheets film as a bifunctional electrocatalyst for efficient water splitting. Inter J Hydrogen Energy 2016;41:7264e9. [10] Wang J, Zhu H, Chen J, Zhang B, Zhang M, Wang L, et al. Small and well-dispersed Cu nanoparticles on carbon nanofibers: self-supported electrode materials for efficient hydrogen evolution reaction. Inter J Hydrogen Energy 2016;41:18044e9. [11] Ambrosi A, Pumera M. Templated electrochemical fabrication of hollow molybdenum sulfide microstructures and nanostructures with catalytic properties for hydrogen production. ACS Catal 2016;6:3985e93. [12] Yu XY, Feng Y, Jeon Y, Guan B, Lou XWD, Paik U. Formation of NieCoeMoS2 nanoboxes with enhanced electrocatalytic activity for hydrogen evolution. Adv Mater 2016. http:// dx.doi.org/10.1002/adma.201601188. [13] Yu L, Xia BY, Wang X, Lou XW. General formation of MeMoS3 (M¼ Co, Ni) hollow structures with enhanced electrocatalytic activity for hydrogen evolution. Adv Mater 2016;28:92e7. [14] Lukowski MA, Daniel AS, English CR, Meng F, Forticaux A, Hamers RJ, et al. Highly active hydrogen evolution catalysis from metallic WS2 nanosheets. Energy Environ Sci 2014;7:2608e13. [15] Lin J, Peng Z, Wang G, Zakhidov D, Larios E, Yacaman MJ, et al. Enhanced electrocatalysis for hydrogen evolution reactions from WS2 nanoribbons. Adv Energy Mater 2014;4:1301875e82. [16] Yang J, Voiry D, Ahn SJ, Kang D, Kim AY, Chhowalla M, et al. Two-dimensional hybrid nanosheets of tungsten disulfide and reduced graphene oxide as catalysts for enhanced hydrogen evolution. Angew Chem Inter Ed 2013;52:13751e4. [17] Sun C, Zhang J, Ma J, Liu P, Gao D, Tao K, et al. N-doped WS2 nanosheets: a high-performance electrocatalyst for the hydrogen evolution reaction. J Mater Chem A 2016;4:11234e8. [18] Deng J, Li H, Xiao J, Tu Y, Deng D, Yang H, et al. Triggering the electrocatalytic hydrogen evolution activity of the inert twodimensional MoS2 surface via single-atom metal doping. Energy Environ Sci 2015;8:1594e601. [19] Wang H, Tsai C, Kong D, Chan K, Abild-Pedersen F, Nørskov JK, et al. Transition-metal doped edge sites in vertically aligned MoS2 catalysts for enhanced hydrogen evolution. Nano Res 2015;8:566e75.



[20] Liu T, Asiri AM, Sun X. Electrodeposited Co-doped NiSe2 nanoparticles film: a good electrocatalyst for efficient water splitting. Nanoscale 2016;8:3911e5. [21] Bonde J, Moses PG, Jaramillo TF, Nørskov JK, Chorkendorff I. Hydrogen evolution on nano-particulate transition metal sulfides. Faraday Discuss 2009;140:219e31. [22] Dai X, Du K, Li Z, Liu M, Ma Y, Sun H, et al. Co-doped MoS2 nanosheets with the dominant CoMoS phase coated on carbon as an excellent electrocatalyst for hydrogen evolution. ACS Appl Mater Interfaces 2015;7:27242e53. [23] Zhang H, Li Y, Xu T, Wang J, Huo Z, Wan P, et al. Amorphous Co-doped MoS2 nanosheet coated metallic CoS2 nanocubes as an excellent electrocatalyst for hydrogen evolution. J Mater Chem A 2015;3:15020e3. [24] Wang J, Cui W, Liu Q, Xing Z, Asiri AM, Sun X. Recent progress in cobalt-based heterogeneous catalysts for electrochemical water splitting. Adv Mater 2016;28:215e30. [25] Pu Z, Liu Q, Asiri AM, Luo Y, Sun X, He Y. 3D macroporous MoS 2 thin film: in situ hydrothermal preparation and application as a highly active hydrogen evolution electrocatalyst at all pH values. Electrochim Acta 2015;168:133e8. [26] Pu Z, Liu Q, Asiri AM, Sun X. Tungsten phosphide nanorod arrays directly grown on carbon cloth: a highly efficient and stable hydrogen evolution cathode at all pH values. ACS Appl Mater Interfaces 2014;6:21874e9. [27] Tian J, Liu Q, Asiri AM, Sun X. Self-supported nanoporous cobalt phosphide nanowire arrays: an efficient 3D hydrogenevolving cathode over the wide range of pH 0e14. J Am Chem Soc 2014;136:7587e90.

9

[28] Zhou X, Chen Q, Wang A, Xu J, Wu S, Shen J. Bamboo-like composites of V2O5/Polyindole and activated carbon cloth as electrodes for all-solid-state flexible asymmetric supercapacitors. ACS Appl Mater Interfaces 2016;8:3776e83. [29] Zhang N, Gan S, Wu T, Ma W, Han D, Niu L. Growth control of MoS2 nanosheets on carbon cloth for maximum active edges exposed: an excellent hydrogen evolution 3d cathode. ACS Appl Mater Interfaces 2015;7:12193e202. [30] Jaegermann W, Ohuchi F, Parkinson B. Interaction of Cu, Ag and Au with van der Waals faces of WS, and SnS2. Surf Sci 1988;201:211e27. [31] Xie X, McCarley RE. Synthesis, structure, and characterization of N-ligated tungsten selenide cluster complexes W6Se8L6. Inorg Chem 1995;34:6124e9. [32] Chowdari B, Tan K, Chia W. Raman and X-ray photoelectron spectroscopic studies of lithium phosphotungstate glasses. Solid State Ionics 1992;53:1172e8. [33] Katrib A, Hemming F, Wehrer P, Hilaire L, Maire G. The multisurface structure and catalytic properties of partially reduced WO3, WO2 and WCþ O2 or Wþ O2 as characterized by XPS. J Electron Spectrosc 1995;76:195e200. [34] Hu B, Jing Z, Fan J, Yao G, Jin F. One-step hydrothermal synthesis of honeycomb 3D graphene-like Co9S8 and its catalytic characteristics for NaHCO3 reduction by H2S. Catal Today 2016;263:128e35. [35] Ihs A, Uvdal K, Liedberg B. Infrared and photoelectron spectroscopic studies of ethyl and octyl xanthate ions adsorbed on metallic and sulfidized gold surfaces. Langmuir 1993;9:733e9.


Effect of Spelt Wheat Flour and Kernel on Bread ... - ACS Publications

Recommend Documents