| 초록 |
The development of electrochemical systems such as water splitting, lithium ion battery, and nitrogen reduction has been researched as eco-friendly and renewable energy to reach growing demands for restricting carbon dioxide emission. Ammonia (NH3) production via nitrogen electroreduction is an attractive alternative candidate to the conventional Haber-Bosch synthesis method, which require high pressure (200-300 bar) and temperatures (300-500 ℃) inducing harsh conditions and release harmful greenhouse gases. However, the electrochemical nitrogen reduction reaction (ENRR) process suffers from low Faradaic efficiency and yield rate for producing NH3 as compete to hydrogen evolution reaction (HER) due to similar reactive potential. For improving properties of ENRR, various efforts have been committed to development of efficient electrocatalyst with limit hydrogen production. Herein, we propose a facile synthesis strategy to electrosynthesis high entropy alloy (HEA) catalyst with up to five equimolar components by confining multiple metal salt precursors to the organic system. Alloys containing five or more equimolar components with a disordered, referred to as high entropy alloy, provide tunable catalytic performance based on the individual properties of incorporated metals. The HEA catalyst provides infinite possibilities for tuning alloy’s electronic properties and maximizing catalytic activity owing to the endless element combination. Notably, the electrosynthesized HEA catalyst achieves the highest Faradaic efficiency of 2.08 % and ammonia yield rate of 7 μg h-1 cm-2 at – 0.3V vs. reversible hydrogen electrode (RHE). The improved ENRR activity can be attributed to solid solution formation, distortion effect, electronic structure changes, and cocktail effect as HEA core effects. Particularly, HEA catalysts, optimizing ENRR activity via electronic structure tuning, can supplant ENRR catalyst revealing low activity due to competition reaction, HER. The application of the HEA catalyst to energy conversion is emphasized with electrocatalytic activity toward ENRR on the CoNiFeSnMn-HEA catalyst. |
