Graphene based sensors for senosr applicatiob.pptx

thesis

1. Reduced graphene oxide as ideal sensing material candidate for chemiresistor systems Tomasz Chudziak

2. Sensors are analytical devices that detect any change or reaction and responds to some type of input from the physical environment Substrate (SiO 2 , Al 2 O 3 …) Sensing material Electrode (Au, Ag, Ti…) Sensory materials may be an organic or inorganic substance that specifically interact with the target analyte , in this case water and gas molecules Currently used sensing materials based on ceramics (in particular Al 2 O 3 and Si 3 N 4 ), metal oxides such as SnO 2 have many limitations including long response time, poor regeneration and low sensitivity to water molecules.

3. Graphene Oxide (GO) Reduced Graphene Oxide (rGO) Graphene (G) [H] [O] Hummer’s method Thermal annealing / chemical reduction Graphene derivatives as sensing materials Great conductivity + Lack of moieties that can be explored for functionalization - High affinity for polar molecules + Electrical insulator - Affinity for polar molecules + Good electrical conductivity +

4. Synthesis and reaction conditions Reductor [H] Symbol Temp. [ o C] Time [h] pH Hydrazine (NH 2 ) 2 95 2 >9 Hydrazine (NH 2 ) 2 95 12 >9 NaBH 4 (NaBH 4 ) 95 2 >9 NaBH 4 (NaBH 4 ) 95 12 >9 Ascorbic acid (AA) 95 2 >9 Na 2 S 2 O 4 (Tio) 95 2 >9 Reduced Graphene Oxide (rGO) Reductor Base: NH 3 K 2 CO 3 Graphene Oxide (GO)

5. Dispersion NMP DMF EtOH Acetone MeCN THF Acetone : H 2 O 2 : 3 Konios , D., et al., Journal of Colloid and Interface Science, 2014.

6. Ren. P.G.. et al.. Nanotechnology. 2011. For NH 2 -NH 2 Sample %N %C %H %S %O C/O ratio rGO( Tio )_12 0.41 84.78 0.65 2.09 14.16 5.99 rGO(NH 2 ) 2 _12 3.63 83.50 0.54 0.74 11.59 7.20 rGO( Tio )_2 0.72 81.47 0.77 2.16 14.88 5.48 rGO(NH 2 ) 2 _ 2 3.35 80.28 0.74 1.01 14.62 5.49 rGO(AA)_2 1.99 75.51 1.03 0.88 20.59 3.67 rGO(NaBH 4 )_2 0.17 65.00 1.73 1.17 31.93 2.04 Chemical composition and stability

7. Chemical composition and morphology Na 2 SO 3 –rGO - C GO - B LAA-rGO - D Musa , N., et al., M.N. Ahmad , et al., Amer Inst Physics : Melville, 2017. rGO(Tio)_2 rGO(AA)_2 rGO(NaBH 4 )_2 rGO(NH 2 ) 2 _2 rGO(Tio)_12 rGO(NH 2 ) 2 _12

8. Isotherm of BET

9. Structure measurements by X-ray diffraction Muruganandi . G.. et al.. Chemical Physics . 2017. Ascorbic acid NaBH4 Hydrazine De Silva. K.K.H.. et al.. Carbon. 2017. rGO via ascorbic acid

10. Surface analysis by X-ray Photoelectron Spectroscopy Sample C1s O1s C1s/O1s ratio C/O ratio rGO( Tio )_12 91.53 8.47 10.81 5.99 rGO(NH 2 ) 2 _12 92.20 6.84 13.54 7.20 rGO( Tio )_2 93.35 6.65 14.04 5.48 rGO(NH 2 ) 2 _ 2 89.41 8.09 11.05 5.49 rGO(AA)_2 90.20 9.80 9.20 3.67 rGO(NaBH 4 )_2 82.48 17.52 4.71 2.04 rGO(AA)_2 rGO(NaBH 4 )_2

11. Applications of rGO rGO Sensors Supercapacitors Biomedical application Composites & Coatings