An effective Fe/Co tripolyphosphate pre-catalyst for oxygen evolution with alkaline electrolyte

Abstract Compounds of transition metal tripolyphosphate are a kind of stable complexes due to the strong coordination interaction between transition metal ions and the tripolyphosphate groups. Herein Fe/Co tripolyphosphate was loaded on carbon nanotube surface through a simple wet-impregnation method. This strategy enables the effective loading of Fe/Co tripolyphosphate on carbon nanotube surface with tunable Fe/Co molar ratios. The obtained composite can be in situ activated during electrochemical test process. When employed as OER catalyst, it shows a lower overpotential (254 mV for 10 mA cm-2) and faster kinetics (Tafel slope of 36.3 mV dec-1). It was found that the Fe/Co tripolyphosphate on carbon nanotubes was transferred into small-sized oxyhydroxide particles embedded in amorphous matrix acting as catalytic active species. This study provides a low-cost, simple but effective way for the synthesis of favorable pre-catalysts for oxygen evolution.