Mg─Bi─Fe‐Oxides/Graphene Electrodes for the Fabrication of Efficient Supercapacitors and Their Use to Accelerate the Growth of Bean Plants

Abstract Ecofriendly supercapacitors (SCs) are fabricated with graphene electrodes printed on recycled‐plastics and utilized seawater as electrolyte. Those devices produced an energy density and capacitance of 50.4 Wh kg −1 and 250.4 F g −1 , respectively. Later, a mixture of Bi─Mg─Fe─O (BMO) oxides is added to the SC electrodes and the capacitance of the devices increased up to 209%. Subsequently, SC electrodes are recovered from used/tested devices and utilized as “seed mats” to grow bean plants. For this purpose, pinto bean seeds are wrapped with recycled SC electrodes and later subjected to a germination treatment together with control seeds. The germination parameters are calculated from the bean plants and found that: 1) 100% of the seeds initially wrapped with the SC electrodes germinated, in contrast, only 88.9% of the control seeds germinated and 2) The bean plants grown with the seed mats has the longest roots/shoots. This occurred because the seed mats have Mg/Fe micronutrients on their surface as well as OH/COOH groups (coming from the seawater), which promote the germination and growth of bean plants. The results of this research demonstrated that SC electrodes coated with BMO can be used as a substrate to promote the growth of bean plants, which is of interest for sustainable agriculture.