Synergistic Inclusion of Reaction Activator and Reaction Accelerator to Ni-MOF Toward Extra-Ordinary Performance of Urea Oxidation Reaction.

Recently electrochemical urea oxidation reaction (UOR) has emerged as the technology of demand for commercialization of urea-based energy conversion. However, the nascent idea is limited by the energy burden of threshold voltage and the sluggish reaction kinetics involving a six-electron transfer mechanism. Herein, for the first time, the engineering of electrocatalysts are proposed with simultaneous inclusion of UOR activator and UOR accelerator. Nitrogen-doped carbon-decorated Ni-based Metal Organic Framework (MOF) has been synthesized as the base catalyst material. MoO and rGO with varied loading have been attached to the MOF to get the desired MoO/Ni-MOF/rGO heterostructure incorporating defects and crystal strain within the materials. Investigations reveal that the invoked lattice strain and atomic defects promote plenteous Ni active sites. The optimized sample demonstrates extraordinary performance of UOR having the potential value as low as 1.32 V versus RHE to reach the current density of 10 mA cm and the tafel slope is only 31 mV dec reflecting very fast reaction kinetics. Here MoO plays the role of UOR activator whereas optimized loading of rGO proliferates the reaction speed. This work, experimentally and theoretically, presents a new insight to enhance electrocatalytic urea oxidation reaction opening an avenue of urea-based energy-harvesting technology.