Project 2

Microwave Synthesis Handout - Ni Doped ZnO

LAB HANDOUT

Microwave-Assisted Synthesis of ZnO and 3 mol% Ni-Doped ZnO Nanoparticles

Supervisor: Dr. Sibi K. S.

Objective: To synthesize ZnO and Ni-doped ZnO nanoparticles using microwave method and study band gap tuning, electrical conductivity, and photoconductivity.

1. Safety Instructions (Strictly Follow)

  1. Wear lab coat, gloves, and safety goggles at all times.
  2. Handle NaOH carefully (corrosive).
  3. Do NOT seal containers during microwave heating.
  4. Use microwave-safe borosilicate glass only.
  5. Allow solution to cool between microwave cycles.

2. Chemicals Required (100 mL Batch)

Undoped ZnO

ChemicalAmount
Zinc acetate dihydrate2.20 g
DI Water100 mL
NaOH (1 M)As required (pH 10)
PEG (optional)0.5 g

3 mol% Ni-Doped ZnO

ChemicalAmount
Zinc acetate dihydrate2.20 g
Nickel nitrate hexahydrate0.087 g (87 mg)
DI Water100 mL
NaOH (1 M)As required (pH 10)
PEG (optional)0.5 g

3. Preparation of 1 M NaOH (100 mL)

  1. Weigh 4.0 g NaOH pellets.
  2. Dissolve in ~70 mL DI water.
  3. Make total volume to 100 mL.
  4. Label properly.

4. Microwave Synthesis Procedure

Step 1: Prepare Precursor Solution

  1. Dissolve 2.20 g zinc acetate in 80 mL DI water.
  2. For doped sample, add 0.087 g Ni nitrate.
  3. Stir for 15 minutes until clear.
  4. Add 0.5 g PEG (optional).

Step 2: Adjust pH

  1. Add 1 M NaOH dropwise under stirring.
  2. Stop at pH 10 (check using pH paper).
  3. White precipitate should form.

Step 3: Microwave Heating

  1. Transfer solution to microwave-safe beaker.
  2. Heat at medium power for 5 minutes.
  3. Remove and cool for 2 minutes.
  4. Repeat heating cycle 3 times.
Expected observation: Thick white precipitate indicating ZnO nanoparticle formation.

Step 4: Washing and Drying

  1. Filter the precipitate.
  2. Wash with DI water 3 times.
  3. Wash once with acetone.
  4. Dry at 80°C for 3 hours.

Step 5: Annealing (Important)

Heat dried powder at 400°C for 2 hours in furnace (minimum 300°C if limited).

Zn(OH)₂ → ZnO + H₂O

5. Characterization Plan

UV-Vis (Band Gap)

  1. Disperse 2 mg powder in 3 mL DI water.
  2. Scan 300–800 nm.
  3. Convert wavelength to energy:
hν (eV) = 1240 / λ (nm)

Plot (Ahν)² vs hν and determine band gap.

FTIR

  • Scan 400–4000 cm⁻¹.
  • Identify Zn–O peak (<600 cm⁻¹).

Electrical Conductivity

R = ΔV / ΔI
ρ = R (A / L)
σ = 1 / ρ

Photoconductivity

S = (I_light − I_dark) / I_dark

6. Weekly Timeline

  • Week 1: Synthesis + drying + annealing
  • Week 2: UV–Vis + FTIR
  • Week 3: Pellet + Conductivity
  • Week 4: Solar simulator + Data analysis

7. Data Submission Checklist

  • UV–Vis raw data + Tauc plots
  • FTIR spectra
  • I–V curves
  • Conductivity calculations
  • Photoresponse graphs
  • Complete lab notebook

End of Handout

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