In situ fabrication of transition metal phosphide tree-like nanostructure for energy-saving hydrogen production coupled via urea oxidation reaction

Abstract

Substituting the Oxygen Evolution Reaction (OER) with the Urea Oxidation Reaction (UOR) which is a thermodynamically more favorable option, has paved the way for the production of energy-saving hydrogen as well as the purification of urea-reach waste water. In this study, a nanostructured, porous and active Ni-Cu-Mn-P electrode was created using the dynamic hydrogen bubble template (DHBT) process in different conditions. The fabricated electrodes were utilized as bi-functional electrodes for both the HER and UOR processes. The electrochemical results displayed that the Ni-Cu-Mn-P (which synthesized at current density of 2 A.cm−2) requires only 84 mV overpotential to achieve a current density of 10 mA.cm−2, in HER process, and the necessary potential value for the UOR is only 1.30 V vs RHE. Also, the favorable electrocatalytic stability for industrial applications was also confirmed. The Ni-Cu-Mn-P electrode also demonstrated satisfactory performance in the overall urea electrolysis process and the cell voltage was 1.40 V to generate 10 mA.cm−2. The excellent performance of the electrode was due to the hierarchical porous nanostructure with high active surface area and also the synergistic effect between the elements. This study introduces an effective catalyst design for energy-saving hydrogen production.