Nickel-Vanadium-Manganese Trimetallic Nitride as Energy Saving, Efficient Bifunctional Electrocatalyst for Alkaline Water Splitting via Urea Electrocatalysis.

Abstract

Hydrogen production through pure water electrolysis is often found less economic as it requires high potential for water oxidation. The presence of urea in water involving effective urea oxidation can be considered as an effective strategy to produce hydrogen economically. Herein, we develop trimetallic nickel vanadium manganese nitride porous microspheres as an efficient bifunctional electrocatalyst for both urea oxidation reaction (UOR) as well as hydrogen evolution reaction (HER) mechanisms. The optimized NiVMn nitride exhibits eye-catching UOR activity along with HER activity that required only 1.36 and -0.253 V electrode potentials, respectively, to achieve a high current density of 100 mA cm-2. Combining its bifunctional activity in UOR and HER in a two-electrode system, an energy saving by 0.26 V potential compared to water electrolysis through water oxidation can be acquired to reach 50 mA cm-2 current density. The presence of manganese(II) has a significant influence in stabilizing high valence V(V) and Ni(II), offering large number of active sites, and during UOR, the effective electronic transitions are more between Mn → Ni rather than Mn → V, leading to excellent and stable UOR performance. Indeed, the electrocatalyst and the approach offering considerable energy saving phenomena are believed to make hydrogen production more economic and sustainable.