Simplified and smart flow reactors for Chemistry, Catalysis and Nanotechnologies

Experimental Procedures

Experimental procedure for carrying out time-resolved in situ kinetic studies on gold nanoparticle formation

Chemicals required: Obtain chloroauric acid (HAuCl4.3H2O) meso-2, 3-dimercaptosuccinic acid (DMSA) and sodium borohydride from Sigma-Aldrich and use all chemicals without further purification. Use nanopure water (18.2 MΩ-cm) for the experiment.

  1. Use Millifluidic device to flow the liquids within the chip. Test the pumps with water as solvent at different flow-rates prior to the experiment to optimize the required flow-rate.
  2. Prepare standard solutions of (i) HAuCl4.3H2O (10 mmol, 118.2 mg/30 ml) and (ii) DMSA (20 mmol, 109.2 mg/30 ml) with 50 mg of sodium hydroxide (pH 12) in nanopure water.
  3. Feed the two solutions through two separate syringes into the millifluidic chip at a constant flow-rate of 10 ml/h using the automated pump.
  4. Couple the millifluidic chip to the synchrotron beam line using a metal stage that has access to movement in XYZ directions and collect the XAS data at different zones on the chip as the solutions were pumped through the chip.


For more information see: J. Am. Chem. Soc., 2013, 135 (14), pp 5450–5456

Experimental procedure for continuous-flow nanostructured gold catalysis


Chemicals required: Obtain chloroauric acid (HAuCl4.3H2O), meso-2, 3-dimercaptosuccinic acid (DMSA), sodium borohydride, 4-nitrophenol, 4-aminophenol from Sigma-Aldrich and use all the chemicals without further purification. Use nanopure water (18.2 MΩ-cm) for the experiment.

Catalyst preparation: Prepare standard solutions of HAuCl4.3H2O (10 mmol, 118.2 mg/30 ml), DMSA (20 mmol, 109.2 mg/30 ml) and NaBH4 (10 mmol, 11.34 mg/30 ml) in Nanopure water.

  1. Take 10 ml each of HAuCl4 and DMSA solutions into two separate vials and flow them within the chip using the hand-held millifluidic device with a uniform flow-rate of 12 ml ml/h for 45 min.
  2. Flow 10 mmol NaBH4 within the chip at 12 ml/h flow-rate for 15 min to reduce the Au(I) to Au(0).
  3. Finally, wash the chip with nanopure water for 30 min at the same flow-rate before conducting the catalysis experiments.
  4. Catalysis reaction: Perform the chemical conversion reaction (reduction) of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) within the gold catalyst (prepared above) coated millifluidic channel as given below.
  5. Mix 15 ml of 9 X 10-5 mol solution of 4-NP with 3.3 ml of 0.65 mol NaBH4 solution to form 4-nitrophenolate ion (4-NPI).
  6. Pass the resultant solution over the gold catalyst deposited within chip at a constant flow-rate of 5 mL/h to evaluate the catalytic activity. Analyze the UV-Vis spectra (using Shimadzu UV 3600 spectrophotometer) of the collected products within the wavelength range of 250 nm to 500 nm to confirm the conversion of 4-NP.
  7. Estimate the catalytic activity of the reaction by obtaining the calibration curve of 4-NPI. Calibration curve can be acquired by plotting the experimentally observed absorption intensity (I) of 4-NPI at different standard concentrations. The peak heights (at 399 nm) for the UV-Vis absorption curves represent the absorption intensity (I) values and according to the Beer Lambert’s law, any change in the peak height value would show corresponding change in its concentration. Therefore, estimate the catalytic activity by finding the difference in initial and final concentrations of the reactant from the calibration curve. For example, if the peak height is 1 unit (Fig.6) it corresponds to a catalytic conversion of 90% (based on the calibration plot).


For more information see:  J. Am. Chem. Soc., 2013, 135 (14), pp 5450–5456

Experimental procedure for synthesis of ultra-small copper nano clusters (UCNCs)

Chemicals required: Obtain copper(II) nitrate hydrate (Aldrich), Sodium borohydride, Sodium hydroxide pellets and O-[2-(3-mercaptopropionylamino)ethyl]-O′-methylpolyethylene glycol (Mw 5000) [MPEG] and use all chemicals without further purification. Use nanopure water (18.2 MΩ-cm) for the experiment.


  1. Use millifluidic device regulated under nitrogen pressure for the experiment. Test the pumps with water as solvent at different pressures prior to the experiment to correlate with the corresponding flow-rates (mL/h). Rinse the millifluidic reactor and tubing with deionized water before initiation of the experiment.
  2. Dissolve 174 mg (0.95 mmol) of copper(II) nitrate and 610 mg (0.122 mmol) of O-[2-(3-mercaptopropionylamino)ethyl]-O′-methylpolyethylene glycol in 28 mL of nanopure water and keep them in a vial to be connected with one input channel.
  3. Keep another solution of 111 mg (2.93 mmol) of sodium borohydride and 102 mg (2.78 mmol) sodium hydroxide in 28 mL (pH ∼ 13) in a different vial and connect it with the other input channel.
  4. Flow both the solutions simultaneously within the millifluidic reactor at different flow-rates (given below) and collect the resulting UCNCs at the outlet in glass vial. Purge the solution with nitrogen and store it under nitrogen.
  5. Operate the pumps under different flow rates at room temperature for the size-controlled synthesis of UCNCs.


 For more information see: Small, 2012, 8 (5), 688–698