Ultrasmall Iron Nanoparticle-Decorated Carbon Black for High-Efficiency Nitrate-to-Ammonia Electrosynthesis and Zinc-Nitrate Batteries
Yingjia Liu, Ruyi Cheng, Huixia Ren, Tengfei Sun, Dong Liu
Abstract
Electrochemical nitrate reduction offers a low-carbon approach to producing ammonia at ambient conditions. However, the development of low-cost but efficient catalysts for ammonia production is still challenging. Herein, we report iron nanoparticles directly decorated carbon black (Fe@C-900) as a low-cost electrocatalyst for high-efficiency nitrate-to-ammonia electrosynthesis, which shows a maximum ammonia Faraday efficiency (FE) of 99% at −0.5 V versus the reversible hydrogen electrode (RHE), a high ammonia yield rate of 12,082 μg h –1 cm –2 at −0.8 V versus RHE, and long-term stability. Combined in situ electrochemical analyses and nitrite reduction tests reveal that the NO 2 * species are the key intermediates for ammonia production. Comparative experiments reveal that iron nanoparticles serve as active sites to produce active hydrogen for further ammonia electrosynthesis. More importantly, the resultant Zn-NO 3 – battery with the Fe@C-900 cathode achieves a large power density of 12 mW cm –2 and a high ammonia FE of 99%. This work provides a low-cost metal-based catalyst for nitrate-to-ammonia electrosynthesis, energy storage, and ammonia production via a Zn-NO 3 – battery.