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UNESCO Laboratory of Environmental Electrochemistry. Charles University in Prague. Heyrovský Institute AS CR. - PowerPoint PPT Presentation
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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: [email protected]
Why new electrode materials• 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
Properties of diamondProperties of diamond
sp3 allotropic modification of carbon
Hardness
Low chemical reactivity
Insulant doping by boron
Low double layer capacity
Broad potential window
Low adsorption
Stability, biocompatibility
Properties of boron doped diamond
Boron doped diamond film electrodes
BDDFE
-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0
pH 9
pH 8
pH 7
pH 6
pH 5
pH 4
pH 3
pH 2
pH 10
pH 11
Cure
nt
E [V]
20 µApH 12
The potential window of BDD electrode, BR buffer pH 2 - 12
CVD - Chemical Vapor DepositionCVD - Chemical Vapor Deposition
Mechanism is not fully understood as yet
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.
Boron doping from solid (boron nitride) or gaseous (boranes,B2H6) sources
CVD - Chemical Vapor Deposition
Boron doped diamond film electrode
BDDFE
Ve sse l
DFE
C o nta c tPla stic p la te
O -se a l ring
Boron doped diamond film electrode (BDDFE)
2
3
4
67
5
1
8
Legend 1. Electrode body2. Screw contact3. Screw attachment4. Small metal spring5. Brassy sheet6. DFE on Si (1,1,1)7. Silicone seal8. Access for solution
Surface of nanocrystalline diamond film electrode on Si
BDDFEGlass 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
Lab made Commercial
Glass tube (1), copper wire (2), conductive epoxide resin (3), non-conductive epoxide
resin (4), silica wafer covered with BDDF (5)
Cyclic voltammogram of 2-nitrophenol at BDDE, BR buffer pH 3
-20
-10
0
10
-1200 -600 0 600 1200
E [V]
I [m
A]
BR buffer pH 3
red-ox
ox-red
E [mV]
2-AB (a), 3-AB (b), and 4-AB (c) DPV at BDNDFE (2-10).10-7 M
pH 7 pH 8 pH 9
DPV at BDDFE 10-5 M 1-nitropyrene 1-aminopyrene
MeOH-BR pufr pH 3 (7:3)
Regeneration
E1 = +800 mV, t1 = 0,3 s
E2 = -500 mV, t2 = 0,2 s
Pasivation1-AP (c = 1·10–4 M) MeOH-BR pufr pH 3 (7:3)
11 measurements
~ +440 mV
Potential span
0 až +1600 mV +230 až +680 mV
DPV at BDDFE of 4-NP (µM) in river water
-600 -800 -1000
-90
-120
-150
-180
I, nA
E, mV
0,0 5,0x10-6 1,0x10-5
0
-40
-80
Ip,nA
c, mol.L-1
850 900 950 1000
180
240
300
I, nA
E, mV
0,0 5,0x10-61,0x10-5
0
30
60
Ip,nA
c, mol.L-1
Reduction Oxidation
0,0 3,0x10-6 6,0x10-6 9,0x10-60
30
60
90
120
I P, n
A
c, mol dm-3
R = 0,9943
DPV 1-AP at BDDFE(0 - 10).10-6 M , MeOH-BR buffer pH 3,0 (7:3)
DPV 1-AP at BDDFE(0 - 10).10-7 M , MeOH-BR buffer pH 3,0 (7:3)
BDDFE detector TL arrangement
1‑AN a 1‑AB (5.10-6 M)DFE(a) a GCE(b)
Elektrochemical wall-jet detector with BDDFE
Counter electrode
Reference electrode
WE
rubber backing
working electrode
rubber gasket
Outlet Inlet
Reference electrode
Kel-f body, top piece
metal backing - - current collector
Kel-f body, bottom piece
screw clamp
FIA-ED or HPLC-ED TL BDDFE
BDDF microelectrodesBDDF microelectrodes
BDDF microelectrodesBDDF microelectrodes
HPLC-ED-BDDFE - 1-AP (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
3,0x10-7 6,0x10-7 9,0x10-7 1,2x10-60,0
1,5
3,0
4,5
6,0
I P,
nA
c, mol dm-3
R = 0,9973
tR = 2,76 min
0,0 4,0x10-7 8,0x10-7 1,2x10-60,0
0,5
1,0
1,5
2,0
2,5
I P,
nA
c, mol dm-3
R = 0,9945
HPLC-ED-BDDFE - 1-HP (HPLC-ED-BDDFE - 1-HP (0-10).10-7 MMeOH:0,05M PhB pH 5,0 (80:20), E = 1000 mV, v = 0,8 ml/min
tR = 3,93 min
HPLC-ED-BDDFE 1-AP in urine after SPEHPLC-ED-BDDFE 1-AP in urine after SPE
(0 - 10).10-8 MMeOH:0,05 M PhB pH (80:20), E = 1000 mV, v =1,0 ml/min
0,0 3,0x10-8 6,0x10-8 9,0x10-8
0,7
1,4
2,1
2,8
I P,
nA
c, mol dm-3
R = 0,9881
HPLC-ED-BDDFE 1-HP in urine after SPEHPLC-ED-BDDFE 1-HP in urine after SPE
(0 - 10).10-8 MMeOH:0,05 M PhB pH (80:20), E = 1000 mV, v =0,8 ml/min
Thank you for your attention