2.4.2. Electrode Preparation

An unmodified glassy carbon paste electrode was prepared by mixing 80% of glassy carbon powder and 20% of paraffin oil in a mortar to form the homogeneous carbon paste. Modified glassy carbon paste electrodes were made by mixing 1.6 weight percent of La(OH)**3**, 0.4% of MWCNTs and 2, 5, and 10% of La(OH)**3**@MWCNTs (with the La(OH)**3** to MWCNT balance being 4:1) in the unmodified paste. Subsequently, the working electrode was filled with the paste, and the electrode surface was polished with paper, washed with DI water, and directly used for measurements.
