Development of Nickel Graphene Oxide Composite Urea Sensor from Cathode Powder of Spent Ni-MH Batteries

The significant growth of energy storage technologies, primarily batteries, has revolutionized many industries. However, their disposal poses serious environmental threats and the scarcity of crucial raw materials necessitates for innovative recycling processes. This study explores the potential of nickel, recovered from spent Ni-MH batteries, as a key component for the development of an electrocatalytic urea sensor. Utilizing a straightforward, rapid, scalable, and environmentally benign electrophoretic deposition process, a high-performance electrode comprised of nickel and graphene oxide was formed on a copper substrate. Structural and morphological properties of the fabricated electrode were characterized by various studies such as Fourier-transform infrared-attenuated total reflectance, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray analysis. The sensing behaviour of the nickel graphene oxide composite electrode towards urea oxidation was evaluated using cyclic voltammetry, linear sweep voltammetry, chronoamperometric techniques and electrochemical impedance spectroscopy modes. The composite electrode demonstrated exceptional sensitivity and selectivity for urea detection, achieving low detection limit of 0.24 μM. The reliability of the sensor over extended periods, its consistent performance, and its suitability for practical applications were also tested. This sustainable approach addresses the growing environmental concern of battery waste and offers a promising solution for efficient urea detection.