Supporting Information

One-dimentional Bi2MoxW1-xO6 sosoloids: controllable synthesis by electrospinning process and enhanced photocatalytic performance

Qinyu Wang, Qifang Lu[*],Xueyang Ji, Zhendong Liu, Mingzhi Wei, Enyan Guo

Shandong Provincial Key Laboratory of Processing and Testing Technology of Glass & Functional Ceramics, School of Material Science and Engineering, Qilu University of Technology, Jinan, 250353, P. R. China

Corresponding author E-mail:(Q. F. Lu).

Tel: 86-531-89631227

Fax:86-531-89631227

Contents

Fig. S1 X-ray diffraction patterns of Bi2MoxW1-xO6 (x=0.2, 0.25, 0.5 and 0.67) nanofiberscalcined at 500 °C for 1 h.

Fig. S1 gives the XRD patterns of the Bi2MoxW1-xO6 (x=0.2, 0.25, 0.5 and 0.67) nanofibers. Allthediffractionpeaks of Bi2MoxW1-xO6 (x=0.2, 0.25 and 0.5) samples can be indexed to the orthorhombic Bi2WO6phase (JCPDS No. 39-0256). With the x value increasing to 0.67, the diffraction peaks located at 2θ= 32.87, 47.16, and 55.93° split gradually, indicating the coexistence of Bi2WO6 and Bi2MoO6 phase (JCPDS No. 21-0102).

Fig.S2Raman spectra of the obtained nanofibers: Bi2MoO6 (a), Bi2WO6 (b), Bi2Mo0.25W0.75O6 (c) calcined at 500 °C for 1 h, respectively.

The peaks located at 142 and 150 cm-1are assumed to reflect the lattice modes of Bi3+ with the perpendicular and translational modes (Zhang et al. 2010). The peaks at 285 and 342cm-1are identified as the EgandEubending modes of MoO6 octahedral unit (Miao et al. 2013).The bands of 796 and 835 cm-1can be specified as the symmetric (A1g) and antisymmetric (A2u) stretching modes of MO6(M=W, Mo) groups,respectively,which includethe motions of apical oxygen atoms. The peak at 711 cm-1might well be interpreted as the antisymmetric bridging mode associatedwith the WO6 octahedra.In more detail,the bands consisted of 205 (Eu), 264 (Eu), 307(Eg) and 416(Eu)cm-1are attributedto the bending of WO6 octahedra (Huang et al. 2012).

Fig.S3Darkadsorptioncurves of RhB (a)and MB (b) dyes over different photocatalysts to achieve an equilibrium adsorption/desorption state, respectively.

Before irradiation, the solution was stirred in the dark for 30 min to ensure the equilibrium between dye molecules and photcatalyst surface.It can be observed that the adsorption capacity ofBi2MoxW1-xO6 for MB and RhB is basically at the same level, so in the present paper, the selection of RhB and MB as model dyes aims to demonstrate theindiscriminate degradation of Bi2MoxW1-xO6photocatalysts for the organic dyes.

Fig.S4Temporal evolution of the spectra during photodegradationof RhB mediated byBi2MoxW1-xO6(x=0, 0.2, 0.25, 0.5, 0.67, and 1) samples.

Fig. S4 reveals the temporal evolutions of the absorption spectra at a time interval of 30 min using Bi2MoxW1-xO6 (x=0, 0.2, 0.25, 0.5, 0.67, and 1) as the photocatalysts. It is noteworthy that the maximum absorbance peak shifts from 553 to 500 nm after 4 h irradiation due to the N-demethylation and deethylation processes (Wang et al. 2015)

Fig.S5Temporal evolution of the spectra during photodegradationof MB mediated byBi2MoxW1-xO6(x=0, 0.2, 0.25, 0.5, 0.67, and 1) samples.

Fig.S6Differentphotodegradation of MB mediated by Bi2MoxW1-xO6(x=0, 0.2, 0.25, 0.5, 0.67 and 1) samples

Fig.S5 and S6 reveal the temporal evolutions of the absorption spectra at a time interval of 0.5 h usingBi2MoxW1-xO6 (x=0, 0.2, 0.25, 0.5, 0.67, and 1) as thephotocatalysts.After 4 h of irradiation, the degradation rate are85%, 87.5%, 98.3%, 76%, 71% and 64% for Bi2MoxW1-xO6 with x=0, 0.2, 0.25, 0.5, 0.67, 1, respectively, while the degradation efficiency of MB for no photocatalyst only as 6.4%, demonstrating the excellentphotocatalytic activity of Bi2Mo0.25W0.75O6 for MB decompositionunder visible light irradiation.

Fig. S7Variation of TOC removal changed versus time for MB solution(a)and HPLC chromatograms of MB solution degraded by Bi2Mo0.25W0.75O6 sample for different time intervalsunder visible light irradiation.

As shown in Fig. S7a, the TOC content in MB reduces to 85.4% finally, which is bigger that the experimental value of photocatalytic degradation. TOC result shows that some intermediateorganic species remain in the solution(Liu et al. 2014). The intermediates of MB during the photodegradation are monitored by HPLC technique (Fig. S7b). The obvious peak of MB at 6 min is observed and diminished gradually with the continuous photocatalytic reaction, indicating that MB is degraded to several intermediates. The structures of the intermediates are regarded as the cleavage of one or more methyl group substituent on the amine groups(Zhang et al. 2014).

Fig.S8Photoluminescence spectra of Bi2MoO6,Bi2WO6 and Bi2Mo0.25W0.75O6 nanofibers.

Fig.S8 shows the PL spectra of Bi2MoO6,Bi2WO6 andBi2Mo0.25W0.75O6nanofibers operating at 350 nm excited light. It is known to all thatthe lower PL intensity, thesmaller probability the photogenerated electron-hole pairsrecombination.The lowest PL intensity of Bi2Mo0.25W0.75O6nanofibers may be attributed to the particular structureconsisted ofthe nanosheets absorbing more photon energy due to multiple scattering.

References

Huang H, Chen HF, Xia Y, Gan YP, Weng XX, Zhang WK (2012) Controllable synthesis and visible-light-responsive photocatalytic activity of Bi2WO6, fluffy microsphere with hierarchical architecture. J Colloid Interf Sci 370:132-138. doi:10.1016/j.jcis.2011.12.056

Liu G, Liu SW, Lu QF, Sun HY, Xiu ZL (2014) BiVO4/cobalt phthalocyanine (CoPc) nanofiber heterostructures: synthesis, characterization and application in photodegradation of methylene blue. Rsc Adv 4:9-14. doi:10.1039/C4RA08759C

Miao YC, Pan GF, Huo YN, Li HX (2013) Aerosol-spraying preparation of Bi2MoO6: A visible photocatalyst in hollow microspheres with a porous outer shell and enhanced activity. DyesPigments 99:382-389. doi:10.1016/j.dyepig.2013.05.005

Wang M, Qiao ZY, Fang MH, Huang ZH, Liu YG, Wu XW, Tang C, Tang H, Zhu HH (2015) Synthesis of Er-doped Bi2WO6 and enhancement in photocatalytic activity induced by visible light. Rsc Adv 5:94887-94894. doi:10.1039/C5RA19164E

Zhang LW, Xu TG, Zhao X, Zhu YF (2010) Controllable synthesis of Bi2MoO6, and effect of morphology and variation in local structure on photocatalytic activities. Appl Catal B Environ 98:138-146.doi:10.1016/j.apcatb.2010.05.022

Zhang M, Xu J, Zong RL, Zhu YF (2014) Enhancement of visible light photocatalytic activities via porous structure of g-C3N4.Appl Catal B Environ 147:229-235. doi:10.1016/j.apcatb.2013.09.002

S1

[*]Author to whom correspondence should be addressed. E-mail: (Q. F. Lu).