[MoS 4 ] 2- -Intercalated NiCo-Layered Double Hydroxide Nanospikes: An Efficiently Synergized Material for Urine To Direct H 2 Generation.

Substituting the energy-uphill water oxidation half-cell with readily oxidizable urea-rich wastewater constructs a ground-breaking bridge, combining the energy-efficient hydrogen generation and environmental protection. Hence, designing a robust multifunctional electrocatalyst is desirable for the widespread implementation of this waste to fuel technology. In this context, here, we report a simple tuning of the electrocatalytically favorable characteristics of NiCo layered double hydroxide by intro-ducing [MoS4]2- in its interlayer space. The [MoS4]2- insertion as well as its effect on the electronic structure tuning is thorough-ly studied via X-ray photoelectron spectroscopy in combination with electrochemical analysis. This insertion induces overall electronic structure tuning of the hydroxide layer in such a way that, the designed catalyst exhibited favorable kinetics toward all the required reactions of hydrogen generation. This is why, our homemade catalyst, when utilized both as a cathode and anode to fabricate a urea electrolyzer, it required a mere 1.37 V cell potential to generate sufficient H2 by reaching the bench-mark 10 mA cm-2 in 1 M KOH/0.33 M urea along with long-lasting catalytic efficiency. Other indispensable reason of selecting [MoS4]2- is its high-valent nature making the catalyst highly selective and insensitive to common catalyst-poisoning toxins of sewage water. This is experimentally supported by performing the real urine electrolysis, where the nanospike-covered Ni foam-based catalyst showed similar performance to that of synthetic urea, offering its industrial value. In addition, our intuition of selecting [MoS4]2- was to provide a ligand-based mechanism for hydrogen evolution half-cell (HER) to preclude the HER-competing oxygen reduction. Another crucial point of our work is its potential to avoid the mixing of two explosive product gases i.e., H2 and O2.