UNESCO Laboratory of
Environmental Electrochemistry
Charles University
in Prague
Heyrovský Institute AS CR
BORON DOPED DIAMOND FILM
ELECTRODES - AN EXCELENT TOOL
FOR VOLTAMMETRIC MONITORING OF
ENVIRONMENTALLY IMPORTANT
ORGANIC SUBSTANCES
Jiri Barek
UNESCO Laboratory of Environmental
Electrochemistry, Department of Analytical
Chemistry, Charles University, Prague, Czech
Republic,
e-mail: Barek@natur.cuni.cz
Why new electrode materials
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•
•
•
•
Broader potential window
Lower noise and background current
Resistance toward passivation
Mechanical stability
Compatibility with „green analytical chemistry“
WHY BORON DOPED DIAMOND
FILM ELECTRODES
•
•
•
•
•
•
Low noise
Broad potential windows
Low passivation
Mechanical and electrochemical stability
Biocompatibility
Comercial availability
Boron doped diamond film electrodes
Properties of diamond
sp3 allotropic modification of carbon
Hardness
Low chemical reactivity
Insulant  doping by boron
Properties of boron doped diamond
Low double layer capacity
Broad potential window
Low adsorption
Stability, biocompatibility
BDDFE
The potential window of BDD electrode, BR buffer
pH 2 - 12
pH 12
20 µA
pH 11
pH 10
pH 9
Curent
pH 8
pH 7
pH 6
pH 5
pH 4
pH 3
pH 2
-2,0
-1,5
-1,0
-0,5
0,0
E [V]
0,5
1,0
1,5
2,0
CVD - Chemical Vapor Deposition
Radicals and other reactive species are
formed in the mixture of methane and
hydrogen. They diffuse to the surface of
growing diamond layer. They react at the
surface and deposits in the form of diamond.
High hydrogen atom concentration prevents
the formation of sp2 carbon species.
Mechanism is not fully understood as yet
Boron doping from solid (boron nitride)
or gaseous (boranes,B2H6) sources
Boron doped diamond film electrode
CVD - Chemical Vapor Deposition
BDDFE
Vessel
DFE
O-seal ring
Contact
Plastic
plate
Boron doped diamond film electrode (BDDFE)
Legend
1
1.
2.
3.
4.
5.
6.
7.
8.
2
3
4
5
6
8
7
Electrode body
Screw contact
Screw attachment
Small metal spring
Brassy sheet
DFE on Si (1,1,1)
Silicone seal
Access for solution
Surface of nanocrystalline
diamond film electrode on Si
BDDFE
Glass tube (1), copper wire (2), conductive epoxide resin
(3), non-conductive epoxide resin (4), silica wafer
covered with BDDF (5), diameter of BDDFE (d, 3 mm),
surface of BDDFE (A, 7,1 mm2).
BDDFE
Glass tube (1), copper wire (2), conductive
epoxide resin (3), non-conductive epoxide
resin (4), silica wafer covered with BDDF (5)
Lab made
Commercial
Cyclic voltammogram of 2-nitrophenol at BDDE,
BR buffer pH 3
10
I [m A]
0
BR buffer pH 3
-10
red-ox
ox-red
-20
-1200
-600
0
600
[V]
E E[mV]
1200
2-AB (a), 3-AB (b), and 4-AB (c)
DPV at BDNDFE (2-10).10-7 M
pH 7
6
a
a
300
I, nA
5
4
3
400
270
5
4
2
1
3
430
0
2
2
1
1
240
0
a
c
6
I, nA
4
3
480
b
5
I, nA
I, nA
pH 9
I, nA
450
pH 8
0
380
350
600
750
900
E, mV
600
700
800
450
E
E,, mV
550
650
750
E
E,, mV
DPV at BDDFE
10-5 M 1-nitropyrene 1-aminopyrene
MeOH-BR pufr pH 3 (7:3)
-1000
reduction 1-NP
I, nA
-500
0
Regeneration
E1 = +800 mV, t1 = 0,3 s
E2 = -500 mV, t2 = 0,2 s
~ +420 mV
~ -720 mV
500
1000
1000
oxidation 1-AP
500
0
-500
E, mV
-1000
-1500
Pasivation1-AP
(c = 1·10–4 M)
MeOH-BR pufr pH 3 (7:3)
11 measurements
Potential span
0 až +1600 mV
+230 až +680 mV
1200
1800
~ +440 mV
800
I, nA
I, nA
1200
600
400
0
0
0
400
800
E, mV
1200
1600
200
400
600
E, mV
DPV at BDDFE of 4-NP (µM) in river water
-80
-180
Ip,nA
300
-40
I, nA
0
-150
0,0
5,0x10
-6
-5
I, nA
1,0x10
-1
c, mol.L
240
60
Ip,nA
30
-120
180
0
0,0
-90
-600
-800
E, mV
Reduction
-1000
850
900
-6
-5
5,0x10 1,0x10
-1
c, mol.L
950
E, mV
Oxidation
1000
DPV 1-AP at BDDFE
(0 - 10).10-6 M , MeOH-BR buffer pH 3,0 (7:3)
250
120
IP, nA
90
200
60
30
I, nA
R = 0,9943
0
0,0
-6
3,0x10
-6
6,0x10
-3
c, mol dm
150
100
300
450
E, mV
600
-6
9,0x10
Ze
2E6
4E6
6E6
8E6
1E5
DPV 1-AP at BDDFE
(0 - 10).10-7 M , MeOH-BR buffer pH 3,0 (7:3)
12
120
Ze
2E7
4E7
6E7
8E7
1e6
IP, nA
9
6
I, nA
3
R = 0,9957
105
0
0,0
-7
4,0x10
-7
8,0x10
-6
1,2x10
-3
c, mol dm
90
75
260
390
520
E, mV
650
BDDFE detector TL arrangement
1-AN a 1-AB (5.10-6 M)
DFE(a) a GCE(b)
Elektrochemical wall-jet detector with
BDDFE
WE
Counter
electrode
Reference
electrode
FIA-ED or HPLC-ED TL BDDFE
Reference electrode
Outlet
rubber gasket
working
electrode
rubber backing
Inlet
Kel-f body, top
piece
metal backing - current
collector
Kel-f body, bottom piece
screw clamp
BDDF microelectrodes
BDDF microelectrodes
HPLC-ED-BDDFE - 1-AP (0-10).10-7 M
MeOH:0,05M PhB pH 5,0 (80:20), E = 1000 mV, v = 1,0 ml/min
1-AP
6
6,0
tR = 2,76 min
4
IP, nA
4,5
3,0
1,5
R = 0,9973
I, nA
0,0
-7
3,0x10
-7
-7
6,0x10
9,0x10
-6
1,2x10
-3
c, mol dm
2
0
0
1
2
t, min
3
Blank
2.10-7
4.10-7
6.10-7
8.10-7
1.10-6
HPLC-ED-BDDFE - 1-HP (0-10).10-7 M
MeOH:0,05M PhB pH 5,0 (80:20), E = 1000 mV, v = 0,8 ml/min
1-HP
2,5
2,1
tR = 3,93 min
2,0
IP, nA
1,5
1,4
1,0
0,5
I, nA
0,0
0,0
R = 0,9945
-7
4,0x10
-7
-6
8,0x10
1,2x10
c, mol dm-3
0,7
0,0
0
1
2
3
t, min
4
5
jen MeOH
1.10-7
2.10-7
4.10-7
6.10-7
8.10-7
1.10-6
HPLC-ED-BDDFE 1-AP in urine after SPE
(0 - 10).10-8 M
MeOH:0,05 M PhB pH (80:20), E = 1000 mV, v =1,0 ml/min
2,8
IP, nA
2,1
1,4
0,7
0,0
R = 0,9881
-8
3,0x10
-8
6,0x10
c, mol dm-3
-8
9,0x10
HPLC-ED-BDDFE 1-HP in urine after SPE
(0 - 10).10-8 M
MeOH:0,05 M PhB pH (80:20), E = 1000 mV, v =0,8 ml/min
-8
-7
1-HP v moči, 1.10 až 1.10 mol dm
-3
2,0
IP, nA
1,5
1,0
0,5
R = 0,9963
0,0
0,0
-8
3,0x10
-8
6,0x10
-3
c, mol dm
-8
9,0x10
Thank you for your attention