Development of low-cost nitrogen- and boron-doped carbon black cathode catalysts for the improvement of hydrogen-bromine flow battery cathode kinetics

Abstract

In this study, carbon blacks, containing nitrogen and boron, are used as cathode catalysts first time in a hydrogen-bromine redox flow cell. Nitrogen and boron doping has been applied to carbon blacks to improve the limited properties of the Vulcan XC72 (VXC). Here, we have examined the effect of nitrogen-/boron-doped Vulcan XC72 carbon black on hydrogen-bromine flow cell performance. Nitrogen gas and boric acid are used as nitrogen and boron sources in the post-doping process, respectively. XRD, SEM, XPS, Raman spectroscopy, and N2 adsorption analyses are used to characterize the structures of cathode catalysts. The electrochemical characterization of the catalysts has been carried out with the cyclic voltammetry technique using the conventional three-electrode system connected to a potentiostat. We have addressed the effect of nitrogen and boron doping into the carbon black onto the flow battery performance by comparing their polarization and power curves. The maximum power densities with the VXC, N-VXC, and B-VXC cathode catalysts have been measured at 0.75 V as 360, 390, and 430 mW cm−2, respectively.