Time‐Decoupled Electrolysis via a Rechargeable Metal‐Urea Battery for Waste Urea Treatment and Hydrogen Production

Abstract The resource utilization of urea wastewater is an important issue in the environmental field. In the present work, urea can be used as the resource of pure hydrogen production by a temporally decoupled rechargeable metal‐urea battery. During the cathodic charging process, urea is dissociated by the reaction of CO(NH ₂ ) ₂ + 6OH ⁻ → N ₂ + 5H ₂ O + CO ₂ + 6e ⁻ to achieve the disposal of urea. Water is splitting into hydrogen (2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ ) during the cathodic discharging process, accompanied with the production of electrochemical energy. The key catalyst layers at the cathode employed bifunctional Ni/Mo ₂ C electrocatalysts for both the urea oxidation reaction (UOR) and the hydrogen evolution reaction (HER). The home‐made Zn–Urea battery can accomplish continuous hydrogen production with a Faraday efficiency of 99% over 20 h, together with a maximum power density of 3.4 mW cm ⁻² . The temporally decoupled rechargeable metal‐urea battery can convert waste urea into high‐value purified hydrogen with partial recovery of electrical energy, offering an impressive resource utilization route for wastewater treatment.