Study of hydrogen redox reactions on platinum nanoparticles in concentrated HBr solutions

► Hydrogen-bromine fuel cells and electrolyzers work with high concentrations of bromide. ► Bromide adsorption on Pt affects its activity toward hydrogen redox reactions. ► Bromide adsorption on Pt from concentrated solution is not reversible as adsorption at low concentration. ► Pt catalyst lose activity after prolong cycling specially in the range potentials of HER relative to HOR.