Dip andElectrochemical Coating of Bio-Synthetic Metallic Nanoparticles forElectrocatalytic Water Splitting Session: 2016-2018Supervised By: Dr. Syeda Rubina GilaniSubmitted By: Zeshan AhmadRegistration No:2016-MPHIL-APP-CHEM-34DEPARTMENTOF CHEMISTRYUNIVERSITYOF ENGINEERING AND TECHNOLOGYLAHORE-PAKISTANResults and Discussion: Nanoparticles of five different metals(W, Ag, Cu, Co and Ni) were prepared with different plant leaves extracts.Different Tests and characterizations of these fabricated FTOs were performed.The results and data of all metal-extract NPs combinations, acquired from theinvestigations are discussed one by one in detail.
But before this, here is thebrief discussion of the techniques used and also the operation which is commonin the characterization of NPs prepared samples.Particle size Analyzer: The particle size of NPs present in liquidsolution was identified by using Particle size analyzer (Anton Paar Litesizer500, using DLS Technology, ?=658 nm). 1 ml of liquid NPs samples of NP solutionwere placed one by one into disposable sample cells at 30oC. Thesesamples were run under standard parameters and results acquired from each runare discussed under their respective heads. UV-Visible Spectrophotometer: Opticalabsorbance spectra of NPs were measured by using Agilent UV-VisibleSpectrophotometer (Carry 60 UV-Vis). About 2 ml of liquid NPs solution wasplaced in sterilized and dry quartz sample cells, sample was run and absorbancewas measured between 200nm to 800nm. This procedure was repeated for allprepared NPs solutions.
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The optical absorbance results of all NPs are discussedin respective sections. Fourier Transform Infrared Spectrometer: Functionalgroup studies were carried out by using Agilent Carry 630 FTIR equipped withDTGS detector. The NPs samples weredried at 200oC in infrared oven (Memmert UN 110 Plus). The driedsamples were run from 650cm-1 to 4000cm-1 and theirtransmittance data was measured. The same procedure was repeated for allsynthesized NPs samples.
Potentiostatic Measurements: Electrochemicaland cyclic voltametric measurements were determined by using Potentiostat(PGSTAT-30, Metrohm AutoLab), having a three-electrode configuration cell.Fabricated FTOs; on which Ag NPs, W NPs, Cu NPs, Co NPs and Ni NPs thin filmswere deposited, were used as working electrodes. An Ag/AgCl (3M KCl) electrodewas used as reference electrode. Platinum plate having 1 cm2 areawas used as counter electrode. Cyclic voltametric measurements were done andcurrent density changes were measured between 1.0V to -0.8V at scan rate 0.2.
Above procedure was repeated with all fabricated FTO plates. During cyclic voltametric analysis onsetpotential and also water splitting was observed. The measured data andgraphical representation of the acquired results is discussed in detail.Antimicrobial Tests: AntibacterialTests were done by following Disk Diffusion Method. There were basically threesteps involved in this test which are as followed.1. Preparationof solid culture media2. Inoculationof sample and Bacterial colony onto the medium & their growth3.
Observationof results and data collection Inthe first step, 4g of nutrient broth and 7.5g of gum agar (purchased from SigmaAldrich) was weighed and added into 200ml of double distilled water. Stirringwas done for 5 minutes at 50oC until all clumps of agar becomesinvisible. When the agar was completely dissolved then 300ml of distilled waterwas added to stirring solution. This solution is stirred for two minutes more,at this time the solution was opaque. Then flask was covered with aluminum foiland tightened with paper tape. This flask was placed into the autoclave andsterilization was carried out at 121OC for 15 minutes.
After that flaskwas removed from autoclave and clear solution was stirred at room temperatureuntil the temperature of the solution drops to 50OC. Next procedurewas performed into the laminar flow cabinet in which a Dettol solution wassprayed to ensure the sterile environment and prevention from any bacterialcontamination due to any already present bacteria in LFC. Sterilized petridishes were taken and about 20 ml the prepared agar media solution was pouredin 25 petri dishes. These plates were remained inside for 30 minutes until theliquid media turned into solid gel. These plates were arranged by placing theirupside down to prevent from moisture and then these media plates were incubatedat 37OC for 24 hours.Insecond step the bacterial culture and sample inoculation on to the preparedagar media was done.
Bacillus subtilisand Pseudomonas aeruginosa were takenas gram positive and gram negative bacteria respectively. Wire loop was takenand it was sterilized by dipping it in 70% ethanol and then placed on burnerflame till red hot. Wire loop was cooled down and dipped into bacterial brothculture without touching the wire loop to the walls of broth culture tube. Thestreaks of bacterial culture were applied on all over the agar plates. NPsoriginal solution without being diluted was used as sample solution.
Paper disks of 6mm diameter was dipped intothe sample solutions and placed over agar plates and pressed little gently withtweezes tip. Then these petri dishes was again covered with lid, labeled andplaced in incubator at 37OC for 24 hrs. After that bacterial growthwas observed and data regarding susceptible or resistive behavior of bacteriato NPs and plant leaves extract without metal was collected. On the basis ofit, zone of inhibition was calculated with the help of scale and antibacterialbehaviors of all NPs are discussed along with snapshots.
Silver Nanoparticles: Silvernanoparticles were prepared by adding metal 1mM solution of AgNO3 todifferent plant leaves extracts resulting in deep brown color NPssolution. After characterization, theresults of all NPs are discussed below.Particle Size Analyzer Results: Theparticle size of all plant extracts was above 100nm as shown in graph but aftermixing with metal solution, different size and shaped particles were formed.Banyan, Sapodilla, Jujube, Lemon and P.
Lime gave NPs with size 1.4nm, 10nm, 11nm,22nm and 47nm respectively. Ag NPs with Banyan, Sapodilla and Jujube providedvery small sized NPs as compared to others. These are average sizes but stillsatisfactory for the confirmation