Unitized Regenerative Fuel Cells: A Review on Developed Catalyst Systems and Bipolar Plates

Severe crisis of energy that our planet is going to face in the near future demands rapid development of alternative energy harnessing and storing devices. Various alternative energy devices have been developed so far, including solar cells, batteries and fuel cells, in order to compete and replace the traditionally used fossil fuel based energy technologies. A very recent addition to the list of such devices is the unitized regenerative fuel cell (URFC), which can function as a dual, i.e., electrolyzer-cum-fuel cell, device. In remote areas, where utilization of conventionally used energy sources results in high expense, URFC can serve as the best energy option, due to its relatively low cost, high efficiency and light weight. URFC utilizes bifunctional electrodes, which function in a dual mode of water electrolysis and fuel cell. The prime focus of URFC research has been to develop various low cost and highly efficient catalysts and catalyst supports towards the fabrication of alternative bifunctional electrodes and to fabricate strong and efficient bipolar plates. The aim of this review is to highlight the main outcomes of these aspects of research on URFCs.