H-cell
(1) Prepare catalyst ink
Prepare your catalyst inks via the following recipes:
(5 mg carbon-based catalyst) + (1 mL of ethanol) + (50 uL Nation solution).
Ultrasonicate the mixture solution for 20 min to obtain homogenously dispersed catalyst ink. If your catalyst powder is not electrically conductive enough, you can add conductive agents, e.g., carbon black, CNT, or graphene.
(2) Clean the working electrode
Ensure that the working electrode (glassy carbon) is clean if it was used in the previous experiments. You may grind the working electrode with aluminum powder (of optimal particle size) by drawing "8" periodically.
(3) Prepare the working electrode
Drop cast your catalyst ink on the working electrode (glassy carbon) using a pipette slowly and gently. Dry it in the air or vacuum oven (60oC).
(4) Assembly of the H-Cell
The counter electrode is Pt mesh (or graphite rod).
For a neutral or alkaline solution, the membrane of the H-cell is an anion-ion exchange membrane (AEM). The AEM should be immersed in 1.0 M KOH for at least 1 hr for activation. It is put between the anode chamber and the cathode chamber.
The reference electrode is Ag/AgCl. The Ag/AgCl electrode and working electrode are located in the same chamber.
(4) Connect WE, CE, and RE from workstation
Connect the WE, CE, and RE from the workstation.
Install gas inlet and outlet. For better sealing, surround the PTFE on the screw. Ensure the O-ring is properly fitted in the gasket to avoid gas leaks.
For the CO2 electrochemical reduction experiment, a magnetic stirrer can be used to enhance the mass transport of dissolved CO2.
The current density tested in H-cell should be < 40 mA/cm2 due to the mass transport of dissolved CO2. A Current density higher than 40 mA/cm2 will force water to decompose involuntarily.
(5) Collect gas products or check gas leakage
To check if there is a gas leakage, one can use a manual bubbler flowmeter to measure the set rate of a mass flow controller (MFC) and the experimental outflow rate. Measure the bubble's rising level (i.e., volume) and the time required by a time watch.
30 sccm = 30 mL per min.
