Validation of High Throughput Electrochemical Gas Sensing

Screening System

Zixuan WangNovember 17, 2014

Background

Harsh combustion environment - 800 °CAccurate and selective to target gas

High Throughput Methodology

Subatomic difference affect large scale

Not feasible to individually test material

High throughput synthesis and characterization methods

High Throughput Methodology

• Normalize affect of distance on the potential

Development of Uniform Standard Sample

Single Cell

Surface Mechanisms

Sensors and Actuators B 121 (2007) 652-663

NO N2O2- O2

O2-O2-

e-

Reflectometry Results - YSZ

• Results confirm relative uniformity of sample (1.8% difference)

XRD Results - YSZ

• XRD analysis using Jade• YSZ Cubic:

– (111): 29.675°– (200): 34.398°

• Confirm identical phases

(1,4) 29.745

(2,4) 29.836 34.848

(3,4) 29.876 34.859

25 27 29 31 33 35 37 39 41 43 450

200

400

600

800

1000

1200

1400

1600

YSZ Post Anneal XRD Uniformity

(1,4)(2,4)(3,4)

Reflectometry Results – WO3

• Confirms relative uniformity (2.5% difference)

• Evidence some parts of the plate that are slightly thicker or thinner

XRD Results – Post Annealed WO3

• XRD analysis using Jade• WO3 monoclinic:

– (002): 23.118°– (020): 23.582°– (200): 24.365°

• Confirm identical phases with phase shifts present

22.5 23 23.5 24 24.5 250

500

1000

1500

2000

2500

3000

3500

4000

WO3 Post Anneal XRD Uniformity

(1,4)(2,4)(3,4)

2θ

Inte

nsity

(1,4) 23.143 23.653 24.362

(2,4) 23.140 23.671 24.397

(3,4) 23.127 23.641 24.377

Reflectometry Results - WO3-YSZ

• Sputtering conditions: same

• YSZ held constant• Confirms relative

uniformity (4.3% difference)

XRD Results – WO3-YSZ Post-annealed

W M(000) WO3 monoclinic: (002): 23.118°(020): 23.582°(200): 24.365°YSZ Cubic: (111): 29.675°(200): 34.398°

W M(020)

W M(200)

Y C(200)

Electrochemical Cell Setup30

electrode probes

Gas inlet

Sample stage

Single Electrochemical Cell Tests

1 10 19 28 37 46 55 64 73 82 91 100 109 118 127 136 145 154 163 172 181 190 199 208 217140

160

180

200

220

240

260 EMF Response of WO3/YSZ/Pt Cell at 600 C

Time (min)

Pote

ntial

(mV)

481

ppm

NO

926

ppm

NO

2083

ppm

N

O 481

ppm

NO

926

ppm

N

O 2083

ppm

N

O

2083

ppm

NO

Electrochemical Cell Tests

400 600 800 1000 1200 1400 1600 1800 2000 2200150160170180

0102030

Sensor Response

Potential Linear (Potential)Change in Potential Linear (Change in Potential)Linear (Change in Potential)

NO Concentration (ppm)

Pote

ntial

(mV)

Chan

ge in

Pot

entia

l (Δm

V)

Multielectrode Cell Tests

0 10 20 30 40 500

20

40

60

80

100

120

140

160

180

200

EMF Response of WO3/YSZ/Pt Cell at 600 C

Time (min)

Resp

onse

(mV)

164

ppm

NO

246

ppm

NO

328

ppm

NO

Conclusions• Designed planar sensor array– Use for combinatorial screening of electrochemical

gas sensors• Confirm deposition uniformity– Reflectometry: thickness– XRD: phases

• Cell potential – Changes valid use of planar sensor design

Future Work

• Create multielectrode with increased surface area/perimeter of the electrodes

• Normalize potential to distance of electrodes• Create multielectrode with different

composition gradient

Acknowledgements

• National Science Foundation (NSF)• University of South Carolina – College of

Engineering and Computing• Strategic Approaches to the Generation of

Electricity (SAGE)• Principal investigators: Dr. Jochen Lauterbach and

Dr. Jason Hattrick-Simpers• Graduate mentor: Ben Ruiz-Yi