Development of Vernonia Amygdalina Photosynthetic Membraneless Electrochemical Cell

Experimental analyses of Vernonia amygdalina pigment from plant collected in Ilorin, Nigeria, have been carried out using spectrophotometer, 1H nuclear magnetic resonance (400Hz) and X-ray diffractometer. Biological membraneless electrochemical cells were fabricated using ground hydrated chlorophyll containing tissues.

The cells were assembled by compaction of hydrated pigment housed in an air-tight 6.5 cm³ cylindrical container, with similar electrodes of copper material. Experimental results showed that the visible part of the electromagnetic spectrum is strongly absorbed at 412 nm and 662 nm by Vernonia amygdalina. The qualitative analysis of the powdered sample of the material showed that the constituents of the sam- ple include Magnesium Carbide (Mg₂C₃), Nitrogen (N₂) and Biuret Hydrate (C₂H₅N₃O₂H₂O). In addition to this, chlorophyll a (chl a) and triglyceride were also shown to be major constituents of the pigment. The particle size of the pigment was deduced using X-ray diffracto- meter to be 2.6 nm, and as such, the processed Vernonia amygdalina pigment is therefore a nano-material for energy conversion by photo- synthetic processes.

The copper-copper electrodes photosynthetic cells generated current of about 4 µA and open circuit voltage of about 5 mV. The current generated by copper-zinc electrodes Photosynthetic Electrochemical Cell (PEC) ranged between 0.2 mA and 1.5 mA, while the open circuit voltage ranged between 0.4 V and 0.9 V. The simple preparation technique adopted, using widely available and low cost natural material showed that a biological photosynthetic electrochemical cell is feasible and promising.