A self-sacrificial templated route to fabricate CuFe Prussian blue analogue/Cu(OH)2 nanoarray as an efficient pre-catalyst for ultrastable bifunctional electro-oxidation

Abstract

Simultaneous achievement of hydrogen production and wastewater treatment is highly demanded owing to the significant energy and environment concerns. Focusing on this topic, electrocatalytic oxidation reactions including the oxygen evolution reaction (OER) and the urea oxidation reaction (UOR) are highly attractive, which could be involved as efficient anodic reactions to couple the cathodic hydrogen evolution reaction (HER) more efficiently. Currently, abundant transition metal-based catalysts have been explored for OER and UOR, while few bifunctional catalysts with versatile application range are reported, and the current activity and operational stability are still unsatisfied. Herein, we proposed a self-sacrificial templated route to fabricate uniform CuFe Prussian blue analogue (PBA) nanocubes grown on Cu(OH)2 nanoarrays as efficient pre-catalysts for both OER and UOR catalysis. After undergoing a pre-oxidation process with substantial accumulation of the active species, highly efficient and ultrastable electro-oxidation behavior can be achieved for promoted OER and UOR. Typically, an ultralow onset potential of 1.423 V vs. RHE with high catalytic current density can be achieved for OER, and an ultralow potential of 1.248 V vs. RHE is required for the optimized catalyst to achieve a 10 mA cm−2 UOR current density. Of note, over 300 h and 150 h stable current can be realized for OER and UOR, accompanied by dramatic increment of the activities. The discovery of the PBA-based pre-catalysts and the investigation of the pre-oxidation process could give useful guidance for future designing of advanced catalysts for the electro-oxidation reactions.