Binder-free electrochemical deposition of 3-D superhydrophilic Cu-Fe-P nanostructure for improving urea oxidation and hydrogen evolution reaction

Abstract

• Cu-Fe-P electrodes were fabricated at various applied current densities. • Electrodeposited electrodes showed favorable catalytic activity for HER and UOR. • Application of UOR instead of OER reduced the overpotential for hydrogen production. Electrochemical water splitting, which includes the hydrogen and oxygen evolution reactions at the cathode and anode surface is one of the eco-friendly and sustainable approaches for hydrogen production. However, due to the needing for high overpotentials in the oxygen evolution reaction (OER) process, electrochemical water splitting still is not economical process. Therefore, replacing the OER with the urea oxidation reaction (UOR) can provide more effective hydrogen production opportunities. Therefore, in this study, by using the electrodeposition process at high current densities and substantial evolution of hydrogen bubbles during the process, the three-dimensional and nanostructured Cu-Fe-P electrode was synthesized. Due to the high active surface area, electrolyte diffusion into all the pores, rapid separation of bubbles, and being binder-free, the deposited Cu-Fe-P electrode at an applied current density of 2 A.cm -2 has the best electrocatalytic performance. It was represented that the value of the needed overpotential for achieving the current density of 10 mA.cm -2 (η 10 ) for the hydrogen evolution reaction (HER) was only 56 mV, and the potential value for obtaining the same current density in the UOR was only 1.295 V (vs. RHE). Similarly, when this electrode was used as a bi-functional electrode in the water-urea electrolysis process, the value of cell voltage was 1.365 V. Also, the prepared catalyst indicated excellent electrocatalytic stability. This work suggests a simple and ultra-fast method for economic electrochemical hydrogen production.