1

Supporting Information

One Step in situ Synthesis of Core-shell Structured Cr2O3:P@Fibrous-

Phosphorus Hybrid Composites with Highly Efficient Full-spectrum-response

Photocatalytic ActivitiesHongpeng Zhoua, Shixin Xub, Dingke Zhangc, Shijian Chena * and Junkai Dengb * aSchool of Physics, Chongqing University, Chongqing, 401331, ChinabState Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049, ChinacCollege of Physics and Electronic Engineering, Chongqing Normal University,

Chongqing, 401331, China.*Corresponding authorE-mail addresses: sjchen@cqu.edu.cn (S. Chen), junkai.deng@mail.xjtu.edu.cn (J. Deng).

Electronic Supplementary Material (ESI) for Nanoscale.This journal is © The Royal Society of Chemistry 2017

2

1. Supplementary figures

2. Theoretical calculations

3. Heterojuction band alignment

4. Reference

3

1. Supplementary figure

10 20 30 40 50 60 70 80 90

Inte

nsity

(a.u

.)

2 (degree)

Cr2O3/3.0P

Cr2O3/2.5P

Cr2O3/2.0P

Cr2O3/1.5P

Cr2O3/1.0P

Cr2O3/0.5P

Cr2O3

a

33 34

2 (degree)

12 14 16 18 20 22 24 26 28 30 32 34

Cr2O3:P@f-P

annealed at500 oC N2 2hC

r 2O3b

Cr 2O

3

Untreated

f-P Cr2O3:P@f-P

Fibrous PInte

nsity

(a.u

.)

Degree (2 10 20 30 40 50 60 70 80 90

Cr2O3:P@f-P

Inte

nsit

y (a

.u)

Degree (2)

Cr2O3

900 oC

Cr2O3:P@f-P700 oC

Cr2O3:P@f-P600 oC

CrP (ICSD no. 42082)

c

Figure S1 XRD patterns of (a) Cr2O3:P@f-P with different P content fired at 700 oC;

(b) comparison of XRD patterns for Cr2O3:P@f-P (m=2.5) and Cr2O3:P@f-P (m=2.5)

annealed in N2 for 2 h; (c) XRD patterns of Cr2O3:P@f-P (m=2.5) calcined at 600 oC,

700 oC and 900 oC.

4

d = 3.54

a b c

c fd

5m

1 2 3 4 5 6 7

0

2

4

6

8

10

Cr Cr

Cou

nts （

× 10

3 （

Energy (keV)

Cr

PO

C

Element Wt% At%Cr 43.23 24.15O 25.38 46.07P 31.16 29.22

e

Figure S2 (a-c) SEM, TEM and HRTEM images of pure Cr2O3; (d-e) FESEM image

and corresponding EDS spectra of Cr2O3:P@f-P (m=2.5).

5

1200 1000 800 600 400 200

700 oC

Inte

nsity

(a.u

.)

Binding energy

900 oC

600 oCCKL1OKLL

CrLM Cr2p

O1sC1s

P2s P2p

Surveya

142 140 138 136 134 132 130 128 126

600 oC

P3-/P0P5+

Binding energy

P2p

Inte

nsity

(a.u

.) 900 oC

700 oC

Binding energy

b

Figure S3 (a) survey XPS spectra of Cr2O3:P@f-P (m=2.5) prepared at different

temperature; (b)The high resolution P2p XPS spectra of Cr2O3:P@f-P (m=2.5)

calcined at 600 oC, 700 oC and 900 oC, respectively.

6

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Cr2O3

Air

N2

Cr2P6O18

Cr2P4O13

Cr(PO3)3

2-Theta

Cr2Cr4(P2O7)4

Inte

nsity

(a.u

.)

Figure S4 the XRD pattern of possible phosphate impurities for Cr2O3:P@f-P (m=2.5) after TGA measurements in the N2 and air atmosphere.

7

0 2 4 6 8 10

0.0

0.2

0.4

0.6

0.8

1.0

1.2

C/C

0

Time (min)

m = 0.0 m = 1.0 m = 1.5 m = 2.0 m = 2.5 m = 3.0

Cr2O3/m P

300 mW/cm2 visble light

Figure S5 Photocatalytic degradation activities of the Cr2O3:P@f-P composites

prepared with different molar ratio (m) of P to Cr2O3 under visible light irradiation

(pH = 7).

8

Pollutants concentration

(mg/L) PhotocatalystsTarget

pollutantsLight source

Light density

(mw/cm2)

Catalyst dosage (mg)

Dosage (ml)

Activity（min）

Degradation efficiency （%）

Ref(year)

10Cr2O3:P@f-P MO

300 W Xe lamp,

> 800 nm95 20

100300 100 % This work

20WS2 MO

5 W NIR LED,

(800-900 nm)95 50

50300 80 %

[1] (2015)

15 ɑ-NaYF4:Yb, Tm/TiO2/rGO

MO2 W LED laser,

980 nm- 65

5720 70 %

[2](2016)

20 ɑ-NaYF4:Yb, Tm/TiO2

MO1 W LED laser,

980 nm- 5

0.51500 70 %

[3](2013)

20ɑ-NaYF4:Yb, Tm/ZnO

RhB2 W LED laser,

980 nm2000 0.5

0.51800 55%

[4](2013)

20 Bi2WO4/TiO2 MO

250 W NIR lamp,

> 760 nm- 20

20120 74 %

[5](2013)

50TiO2/WO3-x MB

200 W NIR lamp,

> 800- 100

50250 30 %

[6](2016)

20CQDS/H-TiO2 MO

250 W NIR lamp

> 760 nm- 20

20120 32%

[7](2015)

20Cu2(OH)PO4 2,4-DCP > 800 nm - -

-360 90 %

[8](2013)

10 Er3+/Yb3+-(CaF2 @TiO2 )

MO500 W Xe lamp,

720-1100 nm- 50

50720 30 %

[9](2013)

50CsxWO3 MB

200 W NIR lamp,

>800 nm42.7 100

50360 37%

[10](2016)

Table S1 Comparison of NIR photocatalytic performance for Cr2O3:P@f-P hybrid

composites with other NIR photocatalysts

9

10 20 30 40 50 60 70 80 90

2 (degree)

Inte

nsity

(a.u

.)

Before catalysis

After catalysis

Figure S6 The XRD patterns of core-shell structured Cr2O3:P@f-P (m=2.5) hybrid

composites before and after photodegradation process.

10

0 5 10 15 20 25 30 35 400.0

0.2

0.4

0.6

0.8

1.0C

OD

t/CO

D0 (

%)

Time (min)

300 mW/cm2

10 mg/L MO20 mg catalyst

Figure S7 the COD removal efficiency of MO under 300 mW/cm2 light density

11

380 400 420 440 46020

40

60

80

100

120

140

160

Cr2O3

Cr2O3:P@f-P

Inte

nsity

(a.u

)

Wavelength (nm)

ex= 290 nm

a

0 200 400 600 8000

2000

4000

6000

8000

10000

-Z'' (o

hm)

-Z' (ohm)

Cr2O3

Cr2O3:P@f-P

b

Figure S8 (a) The photoluminescence spectra (PL) of pure Cr2O3 and core-shell

structured Cr2O3:P@f-P (m=2.5) hybrid composites upon 290 nm light excitation; (b)

EIS Nyquist plots of pure Cr2O3 and core-shell structured Cr2O3:P@f-P (m=2.5)

hybrid composites in the 0.2M Na2SO4 solution.

12

1 μm 0.5 μm

2 μm

Rod

a

1 μm 0.5 μm

2 μm

Flake

Rod

b

1 μm 0.5 μm

2 μmFlake

c

200 250 300 350 400 450 500 550 600 650 700 750 800

Inte

nsity

(a.u

.)

Raman shift (cm-1)

SubstrateNano rodRod/ flake

flake

Cr2O3 d

On the TiO2 nano particle

On the Cr2O3 nano particle Fibrous phase P

Figure S9 (a-c) The SEM image of nano rod, nano rod/ flake and flake morphology

fibrous phase P on the surface of TiO2; (d) The comparison of Raman spectra of

fibrous phase P grown on Cr2O3 and TiO2.

Figure S9(a-c) shows the SEM images of fibrous phase P grown on Cr2O3 and TiO2,

respectively. The results imply fibrous phase P can be different morphologies such as

nanorod, nanoflake synthesized on different particles via adjusting experimental

conditions. The Raman spectra for all the samples can be well indexed to fibrous

phase P.

13

2. Theoretical calculations

The theoretical calculations were carried out with the Vienna ab initio simulation

package (VASP) based on density-functional theory (DFT) using projector augmented

wave (PAW) potentials. 11 The electron exchange correlation interaction was

described by Generalized Gradient Approximation (GGA) with the Perdew-Burke-

Ernzerhof (PBE) exchange correlation functional.12 The LSDA+U (i.e., PBE+U)

method was performed for antiferromagnetic (AFM) Cr2O3, with a small effective on-

site Coulomb energy Ueff of 3.3 eV for the chromium d electrons. The plane wave

kinetic energy cutoff was set at 520 eV, and a 9 × 9 × 9 uniform Monkhorst-Pack k-

grid was used for all calculated cells. Periodic boundary conditions were employed in

all DFT calculations. All atoms were fully relaxed until the Helmann − Feynman

forces were less than 0.001 eV/Å.

Table S2：Formation energy of P impurities in Cr2O3 crystal to form Cr2O3-xPx.

Model 1P atom 2P atom-

1

2P atom-

2

3P atom-

1

3P atom-

2

Concentration (x) 0.0625 0.125 0.125 0.1875 0.1875

Eform (eV) -3.236 -2.922 -2.878 -2.326 -2.609

In order to investigate the P doped Cr2O3, we created a supercell including 80

atoms (32 Cr atom and 48 O atom) of 16 unit cells. We then introduced 1, 2 or 3 P

14

atoms to replace the O atoms randomly distributed. Five models involves different

numbers of P atoms are shown in Figure S10b. The formation energy ( ) of E form

impurity P in Cr2O3 was computed by formula shown as following:

(1)E form (ECr2O3xPx x EO ) (ECr2O3

x EP )

Here, is the energy per unit cell for pure Cr2O3; is the energy per unit 32OCrE xx

E POCr -32

cell for P doped Cr2O3; x represents the concentration of P defects in one unit cell of

Cr2O3 (to form Cr2O3-xPx). and denote the energy of single O atom and single EO EP

P atom for their ground states, respectively. This equation describes the formation

energy of P atoms doped in Cr2O3 to replace O atoms. The calculated formation

energies are in between -2.33 per unit and -3.24 eV per unit as shown in Table S2.

Although they are obviously dependent on the concentration and geometrical

configuration of P impurities, the negative values suggest that P atoms are feasible to

dope into the Cr2O3.

Figure S10a shows that doping one P into Cr2O3 supercell will lead to the

defective bands within the bandgap due to the hybrid of Cr 3p3d4s, O 2p and P 3p.

The curves of band structure presented in Figure S10b demonstrate that the P

impurities contribute the “defective bands” (plotted as red lines) within the band gap.

Compared with different models shown in Figure S10b (1 to 5), the DOS curves

reveals that the defect levels are highly dependent on the concentration and

geometrical configurations of doped P atoms. With the increase of the doping content,

the defective bands with different energy level form within the band gap. It guarantees

the light absorption extending to NIR region.

15

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5-3.6

-1.8

0.0

1.8

-2

-1

0

1

2

-0.32

0.00

0.32

0.64

Energy (eV)

2s 2pO

PDOS

(sta

te/eV

)

3s 3pP

4s 3p 3d Cr

a

16

Figure S10 (a) The calculated density of partial state (PDOS) of Cr2O3:P using the

PBE+U method; (b) The structure details (Color represents: red, O; grey Cr, blue P;),

calculated electronic band structure and density of state (DOS) using the PBE+U

method at different concentration P doing Cr2O3. (1): one P atom randomly

substitution for O sites; (2) and (3): two P atom randomly substitution for O sites; (4)

and (5): three P atom randomly substitution for O sites, respectively.

17

3. Heterojuction band alignment

The conductive band (CB) and valence band (VB) positions of Cr2O3:P can be

estimated by Mulliken electronegativity theory,13 which values at the point of zero

charge can be calculated by following formula:

(2)

g0.5CB

VB CB g

E E EE E E

Where ECB and EVB are the potential of conduction band and valance band,

respectively. χ is the geometric mean of electronegativity of the component atoms, Ec

(4.5 eV) is the scaling factor between the hydrogen electrode scale (NHE) and

absolute vacuum scale (AVS). Here, by using χ= 5.68 and Eg = 2.9 eV, the ECB and

EVB were calculated to be -0.27 V and 2.63 V (vs. NHE, pH = 0), respectively. Here

the obtained band gap (Eg) of Cr2O3:P is 2.9 eV (Figure 3). And the CB potential of

fibrous is -0.9 V vs. NHE ( pH = 0) according to literature. According to the above

values, we draw the schematic diagram of band structures for Cr2O3:P and fibrous P

before contact, as shown in Figure S11. As we have known from the calculated band

structures, the valence band is close to its Fermi level for p-type semiconductor.14

Thus, the Fermi level of Cr2O3:P is more positive than fibrous P. After Cr2O3:P and f-

P contact, the band position of Cr2O3:P will shift upward along with its Fermi level

while those of fibrous P will shift downward along until established the equilibrium of

Fermi level between two semiconductors. Finally, there will be a built-in potential

between the core-shell contact interfaces, which can dramatically enhance the

18

separation of photogenerated electron and holes and then improve photocatalytic

performance.

3.63.02.41.81.20.60.0

-0.6-1.2-1.8-2.4

EF2E(O2/O2

.-, e-)/-0.33 V

E(H+/H2, 2e-)/-0.41 V

Cr2O3:P

vs. NHE ( pH= 7)

e- e- e-

h+ h+ h+

h+ h+ h+

e- e- e-

f-PPotential (V)

P doping defect stateEg =

2.9

eV

2.22 V

-0.68

-1.31 V

0.19VE(H2O/O2, 4h+)/0.82 V

EF1

Eg =

1.5

eV

Figure S11 Schematic diagram of band structures for Cr2O3:P and fibrous P before

contact.

4. Reference

1. Y. Sang, Z. Zhao, M. Zhao, P. Hao, Y. Leng and H. Liu, Adv. Mater., 2015, 27, 363.2. W. J. Wang, Y. C. Li, Z. W. Kang, F. Wang and J. C. Yu, Appl. Catal., B, 2016, 182, 184.3. D. X. Xu, Z. W. Lian, M. L. Fu, B. L. Yuan, J. W. Shi and H. J. Cui, Appl. Catal., B, 2013, 142, 377.4. X. Y. Guo, W. Y. Song, C. F. Chen, W. H. Di and W. P. Qin, Phys. Chem. Chem. Phys., 2013, 15,

14681.5. J. Tian, Y. Sang, G. Yu, H. Jiang, X. Mu and H. Liu, Adv. Mater., 2013, 25, 5075.6. M. Yan, G. L. Li, C. S. Guo, W. Guo, D. D. Ding, S. H Zhang and S. Q. Liu, Nanoscale, 2016,

17828.7. J. Tian, Y. Leng, Z. Zhao, Y. Xia, Y. Sang, P. Hao, J. Zhan, M. Li and H. Liu, Nano Energy, 2015,

11, 419.8. G. Wang, B. B. Huang, X. C. Ma, Z. Y. Wang, X. Y. Qin, X. Y. Zhang, Y. Dai and M. H. Whangbo,

Angew. Chem. Int. Ed., 2013, 52, 4810.9. S. Q. Huang, L. Gu, C. Miao, Z. Y. Lou, N. W. Zhu, H. P. Yuan and A. D. Shan, J. Mater. Chem. A,

2013, 1, 7874.10. G. L. Li, C. S. Guo, M. Yan and S. Q. Liu, Appl. Catal., B, 2016, 183, 142.

19

11. G. Kresse and J. Furthmuller, Comput. Mater. Sci., 1996, 6, 15.12. J. P. Perdew, K. Burke and M. Ernzerhof, Phys. Rev. Lett., 1997, 78, 1396.13. Y. Xu and M. A. A. Schoonen, Amer. Mineral., 2000, 85, 543-556.14. D. Lang, F. Y. Cheng and Q. J. Xiang, Catal. Sci. Technol., 2016, 6, 6207.