Development of Bio-Voltaic Cells from plant extract electrolytes using different electrodes and investigation of their electrochemical performance

Abstract

In this research, bio-voltaic cell (BVC) has been developed using various types of electrodes and Arum Leaf (AL) scientific name Colocasia esculenta and Pathor Kuchi Leaf (PKL) scientific name Briophyllum pinnatum plant extract electrolytes. Various parameters such as open circuit voltage, Voc (V), short circuit current, Isc (A), power (W), voltage efficiency (𝜂v), voltage regulation (VR), power efficiency (ηp), internal resistance (Rint), coulombic efficiency (𝜂Q %), self-discharge characteristics have been measured to check the performance of BVC. Gas Chromatography-Mass Spectrometry (GC-MS) has been carried out to know mainly which compounds of PKL and AL take part to produce electricity in BVC. Apart from this, various electrolytes effects such as, (i) AL living plant, (ii) PKL living plant, (iii) AL extract, (iv) PKL extract on different electrodes, like (i) Zn/Cu, (ii) Ag NPs adsorbed paper, (iii) Reduced Graphene Oxide (RGO) adsorbed paper electrode (iv) RGO-Ag NPs composite paper electrode on cell potential of the developed BVC have been studied to investigate the performance of BVC. In all cases, the effect of the addition of small quantity of secondary salt with electrolytes have been examined. In this study, effect of PKL and AL living plant as electrolyte in BVC has been investigated and it was found that PKL living plant shows better electrical performance than that of AL. The thickness and midrib area of PKL is more than that of AL and it was observed that as the exposed area of midrib of living plant increases, it can act as better electrolyte and show better performance in the developed BVC. As a result, open circuit voltage, Voc (V), short circuit current, Isc (A) and power (W) of BVC using PKL living plant were found to be higher than that of AL living plant. Similarly electrical performance of BVC developed using different electrodes and PKL and AL extract electrolytes have been investigated. Secondary salt plays an important rule to improve the performance of BVC in presence of AL and PKL plant extract electrolytes. When the performance of BVC reduces to a margin level, addition of a small quantity of the secondary salt helps to increase the performance of open circuit voltage, Voc (V), short circuit current, Isc (A) and power (W) of BVC. Moreover, Ag NPs have been synthesized from both PKL and AL and BVC is constructed using this NPs to examine the power generation performance. The performance of BVC changes with changing the size of NPs. The smaller the particle size the higher is the performance of BVC. The size of NPs synthesized from PKL is smaller than that of NPs obtained from AL. Hence, the performance of Ag NPs from PKL is higher than that of AL in BVC. The formation of Ag NPs has been characterized by using XRay Diffraction (XRD), UV–visible spectroscopy, Fourier Transforms Infrared (FT-IR), Energy Dispersion X-ray spectroscopy (EDX), and Field Emission Scanning Electron Microscopy (FESEM). It has been observed that Ag NPs play a decisive role in improving open circuit voltage, short circuit current, and thus enhance the power generation of BVC. The highest open circuit voltage (Voc) of 0.45 (V) has been found for the constructed BVC using AL extract and the highest value of Voc has been found to be 0.92 (V) for the developed BVC using PKL extract. The value of Voc is found to be 1.10 (V) when small quantity of secondary salt is added with AL extract and Voc value is found to be 1.34 (V) when a small quantity of secondary salt is added with PKL extract electrolyte. The open circuit voltage (Voc) of 1.28 (V) has been found when BVC is constructed using Ag NPs adsorbed paper electrode with AL extract and Voc value of 1.41 (V) is observed when BVC is developed using Ag NPs adsorbed paper electrode with PKL extract electrolyte. However, maximum open circuit voltage (Voc) of 1.51 (V) has been found for the BVC developed using secondary salt diluted AL extract and Ag NPs adsorbed paper electrode and a maximum open circuit voltage (Voc) of 1.63 (V) has been found for the BVC developed using secondary salt diluted PKL extract and Ag NPs adsorbed paper electrode. viii Moreover, the highest short circuit current, (Isc) of 110 (mA) has been found for BVC developed using AL extract and the highest Isc is found to be 260 (mA) when PKL extract electrolyte is used in BVC. Beside this, Isc value of 450 (mA) has been found using secondary salt with AL extract electrolyte and Isc value of 545 (mA) has been found using PKL extract electrolyte in BVC. Isc value of 820 (mA) has been found using Ag NPs with AL extract and Isc value of 915 (mA) is found when PKL extract electrolyte is used with Ag NPs in BVC. However, maximum Isc of 960 (mA) and 981 (mA) have respectively been found for the developed BVC using secondary salt diluted AL extract and PKL extract with Ag NPs adsorbed paper electrodes. Power, Pmax = Voc × Isc (W) of the developed BVC cell also increases similarly. In addition, chemically synthesized RGO has been prepared by modified Hummers’ method which has been deposited on the surface of cellulose paper. This RGO adsorbed cellulose paper has been applied in BVC as electrode. Thus, RGO and AgNPs deposited on cellulose paper have been mixed together to construct a highly conductive RGO/AgNPs hybrid electrode for BVC. In this research, attempts have been taken to investigate the effect of AL and PKL extract electrolytes with Zn/Cu (1cm2) electrode, Zn/ RGO absorbed paper electrode, Zn/ RGO wrapped Ag NPs composite paper electrode to construct BVC and to examine which BVC can generate enough electricity for the longest period. It is observed that, the highest open circuit voltage (Voc) 0.95 (V) has been found using Zn/Cu (1 cm2) electrode with AL extract and that of 1.00 (V) has been found using Zn/Cu (1 cm2) electrode with PKL extract in BVC. Apart from this when BVC is constructed using Zn/ RGO (2 h) electrode with AL electrolyte, a Voc of 0.99 (V) has been found and when BVC is developed using Zn/ RGO (2 h) electrode with PKL extract electrolyte a (Voc) value of 1.20 (V) is observed. The BVC constructed using Zn/ RGO (24 h) wrapped Ag NPs with PKL extract exhibit higher value of Voc of 1.34 (V) than that of BVC developed using Zn/ RGO (24 h) wrapped Ag NPs with AL extract (Voc value of 1.21 V). Again, the highest short circuit current, (Isc) of 110 (mA) has been found for BVC constructed using Zn/Cu (1 cm2) electrode with AL extract and Isc of 178 (mA) has been observed for BVC developed using Zn/Cu (1 cm2) electrode with PKL extract. Beside this, Isc of 215 (mA) has been found for BVC constructed using Zn/ RGO (2 h) electrode with AL electrolyte and Isc value of 210 mA is found when BVC is developed using Zn/ RGO (2 h) electrode with PKL extract electrolyte. A short circuit current, (Isc) of 297 mA has been found using Zn/ RGO (24 h) electrode with AL electrolyte and Isc of 320 mA has been observed when BVC is made using Zn/ RGO (24 h) electrode with PKL electrolyte. On the other hand, 346 (mA) has been found when the cell is made by using Zn/ RGO (2 h) wrapped Ag NPs with AL extract and Isc of 410 (mA) has been found for the cell of Zn/ RGO (2 h) wrapped Ag NPs and PKL extract electrolyte. However, maximum short circuit current, (Isc) of 423 mA has been found for the cell made of Zn/ RGO (24 h) wrapped Ag NPs with AL extract and Isc of 496 (mA) is found when the cell is made using Zn/ RGO (24 h) wrapped Ag NPs with PKL extract electrolyte. Power, Pmax = Voc × Isc (W) also increases similarly. The developed BVC has been compared with Traditional Voltaic Cell (TVC) using various types of electrodes and electrolytes and it is observed that BVC shows better performance for longer time than that of TVC. The highest longevity of open circuit voltage, Voc (V) of TVC is 470 minutes whereas BVC is 1090 minutes. The highest longevity of short circuit current, Isc (A) of TVC is 320 minutes and for BVC Isc last for 1090 minutes. Again, the highest longevity of power of TVC is 320 minutes while that of BVC is 1090 minutes using same parameters. Because, the strength of H2SO4 runs out within 320 minutes but strength of plant extract electrolytes does not run out up to 1090 minutes. This developed BVC is able to produce enough electricity to energize a few LED bulbs and to run a ceiling fan. ix Finally, from this study, it is possible to design a 1 KW mini power plant using different electrodes and AL and PKL extract electrolytes with an affordable price. This mini power plant can be a source of power generation and may be utilized for distributing electricity, where the nationwide grid is out of reach.