Abstract:
This study aimed at designing a simple and facile strategy of incorporating highly desirable nanoclusters of
non-precious cobalt metal along with nitrogen (Co-NSC) into the carbon matrix for HCl electrolysis. The in
situ co-insertion of Co and N was found to impart bifunctionality facilitating both the oxygen reduction
reaction (ORR) at the oxygen depolarized cathode (ODC) and chlorine evolution at the chlorine evolving
anode (CEA) in HCl electrolysis. Improvement in the kinetics and energetics of these reactions is
expected to benefit from the improved energy quotient and waste HCl utilization towards greener
commodity chemicals. Optimization of the Co-NSC catalyst synthesis was carefully performed using
a Co-based complex by varying the thermal treatment conditions which largely impacted the
composition of Co : N in the catalyst and also guided the obtainable morphology. Once synthesized
a thorough investigation of the Co-NSC variants was performed using a range of physicochemical and
analytical investigations to determine the most active Co : N composition and morphology facilitating
bifunctional electrocatalysis at the ODC and CEA. The electrochemical activities observed were
compared against those of benchmark and industrially applicable catalysts both under mild (0.4 M HCl)
and stringent corrosive conditions (5 M HCl). Not just activity but stability of this carefully designed
catalyst was later confirmed by performing accelerated degradation tests over the duration of a month
and post analysis of the recovered catalyst. The visualization of the local electrocatalytic activity of the
proposed catalyst towards the ORR was evaluated using scanning electrochemical microscopy
