Rajan Saini

Phthalocyanine based nanowires and nanoflowers as highly sensitive room temperature Cl2 sensors

Nanowires of Zn(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (ZnPcOC8) and nanoflowers of Cu(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (CuPcOC8) have been uniformly grown onto glass substrate by employing a cost effective solution based self-assembly technique. The nanowires and nanoflowers were characterized by XRD, SEM and UV-Visible absorption spectroscopy. It has been demonstrated that these nanowires and nanoflowers were highly sensitive towards Cl2 at room temperature with a detection limit as low as 5 ppb. The response of nanowires and nanoflowers varied linearly from 93% to 715% and 85% to 550% for 5–1500 ppb of Cl2. Raman spectroscopic and XPS studies revealed that the central metal ions of ZnPcOC8 and CuPcOC8 were the predominant absorption sites for Cl2. The results emphasized the application of these nanostructures as low cost and highly sensitive room temperature Cl2 sensors.

Substituted copper phthalocyanine/multiwalled carbon nanotubes hybrid material for Cl2 sensing application

In this work, hybrid of soluble copper phthalocyanine (CuPcOC{sub 8}) and functionalized multi-walled carbon nanotubes (MWCNTs) has been synthesized. The formation of CuPcOC{sub 8}-MWCNTs hybrid is confirmed by atomic force microscopy, UV-Visible and FTIR spectroscopy. Subsequently, a chemi-resistive sensor is fabricated by drop casting CuPcOC{sub 8}-MWCNTs hybrid onto glass substrate. It has been demonstrated that CuPcOC{sub 8}-MWCNTs hybrid is highly selective towards Cl{sub 2} gas with minimum detection limit of 100 ppb. The response of sensor increases linearly with increase in the concentration of Cl{sub 2} gas. For 2000 ppb of Cl{sub 2}, CuPcOC{sub 8}-MWCNTs hybrid gives a response as large as 53% in 40 seconds.

Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC8/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC8 derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO2, NO, Cl2 and NH3 at operating temperature of 150˚C. It has been demonstrated that for Cl2 minimum detection limit of CuPcOC8/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl2.

Substituted zinc phthalocyanine based nanowires for room temperature ppb level Cl2 sensing application

Nanowires of substituted Zinc phthalocyanine have been uniformly grown onto glass substrate by cost effective self-assembly technique and their Cl2 sensing properties have been studied at room temperature in the range 5–1500 ppb. The formation of nanowires is attributed to π-π interactions between the molecules. The density and dimensions of nanowires is found to be dependent upon the concentration of solution. It has been demonstrated that these nanowires are highly sensitive and selective to Cl2. The nanowires exhibit a response as high as 570% with a fast response time of 15 sec for 1500 ppb of Cl2 while the minimum detection limit is as low as 5 ppb. XPS studies reveal that predominant sites of interaction of chlorine are central metal ions of substituted zinc phthalocyanine molecules. The studies emphasize their application as low cost room temperature ppb level chlorine gas sensor.

Zinc phthalocyanine nanowires based flexible sensor for room temperature Cl2 detection

We have fabricated highly sensitive and Cl2 selective flexible sensor by depositing solution processed zinc phthalocyanine nanowires onto the flexible PET substrate and studied its Cl2 sensing characteristics in Cl2 concentration range 5-1500 ppb. The flexible sensor has a minimum detection limit as low as 5 ppb of Cl2 and response as high as 550% within 10 seconds. Interestingly, the sensor exhibited enhanced and faster response kinetics under bending conditions. The gas sensing mechanism of sensor has been discussed on the basis of XPS and Raman spectroscopic studies which revealed that zinc ions were the preferred sites for Cl2 interactions.We have fabricated highly sensitive and Cl2 selective flexible sensor by depositing solution processed zinc phthalocyanine nanowires onto the flexible PET substrate and studied its Cl2 sensing characteristics in Cl2 concentration range 5-1500 ppb. The flexible sensor has a minimum detection limit as low as 5 ppb of Cl2 and response as high as 550% within 10 seconds. Interestingly, the sensor exhibited enhanced and faster response kinetics under bending conditions. The gas sensing mechanism of sensor has been discussed on the basis of XPS and Raman spectroscopic studies which revealed that zinc ions were the preferred sites for Cl2 interactions.

Improvement of room temperature ppb level Cl2 sensing characteristics of copper phthalocyanine film

Room temperature ppb level Cl2 sensing characteristics of 50 nm films of copper phthalocyanine (CuPc) and its non-peripheral derivative Cu(II) 1,4,8,11,15,18,22,25-octabutoxy-29H, 31H-phthalocyanine (CuPcOC4) have been studied in the 5-1500 ppb range. By making butoxy substitutions at non-peripheral sites of CuPc molecule, the detection limit of film is lowered from 50 ppb to 5 ppb with faster response and recovery time as compared to unsubstituted CuPc film of same thickness. For 1500 ppb of Cl2, the response of CuPcOC4 film is four times higher than CuPc film. These results are further enhanced by using self-assembled nanowires of CuPcOC4. The response of nanowires is five times higher than unsubstituted CuPc film with response and recovery time of 20 sec and 270 sec for 1500 ppb of Cl2.

Solution processed CuPc based nanowires for room temperature Cl2 gas sensing applications

Self assembled nanowires (NWs) of Cu (II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-Phthalocyanine (CuPcOC4) molecule have been grown on glass substrate by solvent vapours annealing approach. The density and dimensions of NWs is found to be dependent on the concentration of solution and time of exposure. The possible formation mechanism of these structures is π-π interaction between phthalocyanine molecules. The improved conductivity of these NWs can be due to 1D co-facial arrangement of molecules in NWs. Nws are found to be selective for Cl2 gas at room temperature. The room temperature Cl2 sensing characteristics of NWs have been discussed in this paper.Self assembled nanowires (NWs) of Cu (II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-Phthalocyanine (CuPcOC4) molecule have been grown on glass substrate by solvent vapours annealing approach. The density and dimensions of NWs is found to be dependent on the concentration of solution and time of exposure. The possible formation mechanism of these structures is π-π interaction between phthalocyanine molecules. The improved conductivity of these NWs can be due to 1D co-facial arrangement of molecules in NWs. Nws are found to be selective for Cl2 gas at room temperature. The room temperature Cl2 sensing characteristics of NWs have been discussed in this paper.

Phthalocyanine based 1D nanowires for device applications

1D nanowires (NWs) of Cu (II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-Phthalocyanine (CuPc(OBu)8) molecule have been grown on different substrates by cost effective solution processing technique. The density of NWs is found to be strongly dependent on the concentration of solution. The possible formation mechanism of these structures is π-π interaction between phthalocyanine molecules. The improved conductivity of these NWs as compared to spin coated film indicates their potential for molecular device applications.

Room Temperature ppb Level Chlorine Gas Sensor Based on Copper (II) 1, 4, 8, 11, 15, 18, 22, 25‐octabutoxy‐29 H, 31 H‐phthalocyanine Films

Spin coating technique has been used to fabricate room temperature chlorine gas sensor based on copper (II) 1, 4, 8, 11, 15, 18, 22, 25‐octabutoxy‐29 H, 31 H‐phthalocyanine (CuPc(OBu)8) films. Gas sensor shows a response of 185% to few parts per billion level of Cl2 gas with response time of 9.5 minutes at room temperature. The interactions between sensor and analytes followed first order kinetics with rate constant 0.01≤k≤0.02. The chemiresistive sensor showed very good stability at room temperature over a long period of time.