Cyclic voltammetric electrodeposition of iron-cobalt electrocatalyst for boosting urea oxidation reaction in alkaline-seawater solution
摘要
Electrolysis of seawater presents a sustainable pathway to green hydrogen production, utilizing both the abundant source of seawater and from renewable energy. Yet, the slow anode oxygen evolution reaction (OER) necessitates alternative, where urea oxidation reaction (UOR) intermediate shows promise due to its favorable thermodynamic potential. In this work, we report a simple synthetic method to prepare an iron-cobalt (Fe–Co) electrocatalyst directly onto Ni foam via cyclic voltammetric (CV) electrodeposition. The catalyst demonstrates outstanding UOR activity in 1 M KOH + 0.33 M urea seawater, achieving low potentials of 1.335 V and 1.458 V at 10 and 100 mA·cm−2, respectively, a Tafel slope of 133.8 mV·dec−1, and a charge-transfer resistance (Rct) of 0.81 Ω. It exhibits a high mass activity of 13.24 mA·mg−1 at 1.45 V and maintains stable operation for over 70 h at 10 mA·cm−2. The excellent UOR performance, coupled with the electronic structure reconstruction induced by Co doping, suggests the formation of more active sites with optimized electronic configurations, which favors the key steps of urea oxidation. Additionally, the superhydrophilic surface of the electrocatalyst Fe–Co permits quick and complete electrolyte infiltration, which creates a highly accessible reaction interface and therefore increases catalytic activity. Given its low-cost synthesis, simple preparation method, remarkable UOR activity, and long-life operation stability, the electrocatalyst Fe–Co is one of the most promising candidates to enhance urea-assisted, sustainable electrolytic hydrogen production technologies.