In‐Situ Grown Mixed‐Linker Based Redox‐Active Cd (II)‐Metal Organic Framework on Nickel Foam: A Self‐Supported Trifunctional Electrocatalyst for Energy‐Efficient Urea‐Assisted Overall Water Splitting

The production of hydrogen fuel via water electrolysis has emerged as one of the energy conversion technique to alleviate the global energy scarcity. The search for non-noble metal based active electrocatalyst to accelerate water electrolysis process has become one of the challenging task. Here, a suitable and facile one-step solvothermal method has been followed for the growth of Cd based pristine metal organic frameworks (MOFs) onto nickel foam (NF). The binder-free three-dimensional (3D) Cd (II)-BPFA-MOF/NF electrode exhibits an excellent performance toward urea-assisted water splitting. The electrocatalyst Cd (II)-BPFA-MOF/NF showed an overpotential of 148 and 420 mV at benchmark current density of 10 mA cm^-2 in 1 M KOH medium for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. At the same time, Cd (II)-BPFA-MOF/NF exhibit only 1.59 V for urea oxidation reaction (UOR) at benchmark current density in 1 M KOH and 0.33 M urea medium. The Cd (II)-BPFA-MOF/NF || Cd (II)-BPFA-MOF/NF bifunctional electrodes demands only 1.54 V potential to achieve a current density of 10 mA cm^-2 toward urea-assisted overall water splitting reaction (UOWS) with remerkable long-term stability. Therefore, this work represents application of a waste to wealth approach toward Cd-based sustainable electrocatalyst for renewable hydrogen production.