Defect engineering of Na-induced oxygen vacancies in nickel ferrite for dual site electrocatalytic water splitting

Abstract

Electrocatalytic materials for clean energy production was been a challenging research task in the recent years. Various materials have been engineered over the years for electrocatalytic water splitting. Adhering to this aspect, a novel electrode with bifunctional OER mechanism was developed by Na incorporation in nickel ferrite and electroless NiP deposition. Fine-tuning the oxygen vacancy by introducing Na and filling the Na-induced oxygen vacancies by active phosphorus sites generated the electrode system that can participate effectively in alkaline OER. The high OER efficiency of the electrode was due to its surface functionalities and good electron conductivity, which directed OER via a dual functional mechanism involving OVSM and AEM. The compact electrode with very fine morphology, functional component, Na-induced oxygen vacancies, phosphorus active sites and metals’ redox couple boosted the OER. As an indicator of OER efficiency, the developed electrode exhibited a Rct value as low as 784 ohm at open circuit potential. The functional catalyst incorporation in NiP resulted a fourfold increase in ECSA and a lower OER overpotential of 310 mV at 10 mA cm-2. Further the stability tests and the comparative study of the OER results indicating the systems’ performance and promising electrochemical characteristics suitable for large scale applications. The photo catalytic hydrogen production performance under sunlight revealed that the developed plate was able to produce 1.86 mmol.cm-2 hydrogen for 5h and was able to produce a high photocurrent of 11.4 mA.cm-2 at 1.54 V vs.RHE under light illumination.