Self-supported Co-doped FeNi carbonate hydroxide nanosheet array as a highly efficient electrocatalyst towards the oxygen evolution reaction in alkaline solution
Molecular hydrogen evolution from electrochemical water splitting has currently emerged as one of the promising strategies to address the ever-increasing energy crisis and environment pollution, in which the development of low-cost, highly-efficient and durable electrocatalyst is still challenging to the practically large-scale applications of water splitting. Herein, a high single-crystallized Co-doped FeNi carbonate hydroxide nanosheet array strongly grown on conductive nickel foam (Co-FeNi CH/NF) was easily prepared and used as an oxygen evolution reaction (OER) electrocatalyst. The trimetallic Co-FeNi CH/NF electrode exhibits improved OER activity and good long-term durability for at least 20 hours, which can deliver the current densities of 10 and 500 mA cm-2 at extremely low overpotentials of 202 and 254 mV along with a small Tafel slope of 37.5 mV dec-1 in 1.0 M KOH electrolyte. The incorporation of equivalent Co species into the trigonal FeNi CH crystal lattice has significantly increased the electrochemical active surface area for exposing more accessible active sites and reduced the electron and mass transport resistance, which become the main reason responsible for the boosting OER activity. These interesting observations highlight the importance of the subtle combinations of the active earth-abundant metals on the conductive substrate.