Nature - USA (2020-01-23)

Nature | Vol 577 | 23 January 2020 | 495

Bulk WS 2

H 2 S

MAX-(W2/3Y1/3) 2 AlC

Y-doped WS 2

500 nm

1 nm

0.27 nm

(100)

1 nm HAADFW1 nm 1 nm YS1 nm

ab c

defg

hij

Intensity (a.u.)

Raman shift (cm–1)

200 250300 350 400 450 500

E2g^1 A1g

Y-doped WS 2

Energy (eV)

17,050 17,100 17,150

Y 2 S 3

Y- doped WS 2

Y 2 O 3

Y 2 S 3

Y- doped WS 2

Y 2 O 3

Y–O

Y–S

Radial distance (Å)

0123456

Fourier transform,

(^3) k
F(k
)
Intensity (a.u.)
Fig. 3 | Structural characterization of 2D heteroatom-doped transition-
metal chalcogenides with 2H phase derived from quaternary MAX phases.
a, Schematic illustration of the conversion of quaternary MAX-(W2/3Y1/3) 2 AlC to
Y-doped WS 2. b, Typical scanning electron microscope image of Y-doped WS 2 ,
showing the expanded structure. c, d, High-resolution TEM (c) and high-angle
annular dark-field (d) images of Y-doped WS 2 layers. e–g, Elemental mapping
images of W (e), Y (f) and S (g) species in Y-doped WS 2 layers. h, Raman spectra
of Y-doped WS 2 and bulk WS 2. i, j, Y K-edge XANES spectra (i) and Fourier
transform spectra (j) of Y K-edge EXAFS for Y-doped WS 2 , demonstrating the
presence of Y–S bonds in Y-doped WS 2.
Line 1
Y, P co-dopedWS 1T
2
W
Y
S
0.5 nm
abd
c
efg
Position (nm)
0.0 0.5 1.0 1.5 2.0 2.5
Intensity (a.u.)^6
8
10
12
(^14) Line 1
SS SS SS SS SS
W WWW W
100200 300400 500
Raman shift (cm–1)
Intensity (a.u.)
J 1
J 2
J 3
E2g^1 A1g
Y- doped WS 2
Y, P co-doped WS 2
Intensity (a.u.)
0 123456
Radial distance (Å)
Y, P co-doped WS 2
Y 2 O 3
Y 2 S 3
YP
Y–O
Y–P
Y–S
Energy (eV)
2,120 2,140 2,160 2,180 2,200 2,220
Y, P co-doped WS 2
YP
P 4 S 10
P–Y
P–S
Y- doped WS 2
Y, P co-doped WS 2
Exfoliated WS 2
Curr
ent (
μA)
3
2
1
0
1
–2
–3
Potential (V)
–1.0 –0.5 0.0 0.5 1.0
–10
Curr
ent (nA)^0
5
10
–5
Potential (V)
–1.0–0.50.00.51.0
Fourier transform,
(^3) k
F(k
)
Fig. 4 | Structural characterization and electrical properties of 2D
heteroatom (Y and P) co-doped WS 2 with 1T phase derived from quaternary
M A X- ( W2/3Y1/3) 2 AlC. a, Atomic-resolution STEM image and its corresponding
fast Fourier transform patterns (inset). b, Atomic configuration of Y,
P co-doped WS 2 , exhibiting the 1T phase. c, Line intensity profile along the
highlighted arrow in a. d, Raman spectra of Y, P co-doped WS 2. e, Fourier
transform spectra of Y K-edge EXAFS. f, P K-edge XANES spectra for Y,
P co-doped WS 2. g, Current versus voltage curves of Y, P co-doped WS 2 , Y-doped
WS 2 and exfoliated WS 2.