The fixation of nitrogen to produce ammonia is performed on a large scale using the very energy-intensive Haber-Bosch process. This process requires high temperatures and pressures. The electrochemical fixation of N₂ under ambient conditions could be an alternative, but requires improved electrocatalysts for the N₂ reduction reaction (NRR).

Tingshuai Lie, Xuping Sun, University of Electronic Science and Technology of China, Sichuan, and colleagues have developed an efficient electrocatalyst for the NRR, composed of cubic SnO₂ sub-micron particles on a carbon cloth (SnO₂/CC). The team prepared the catalyst by immersing a strip of CC in an aqueous solution of SnCl₄ and NaOH and heating it to 200 °C for 24 h.

The prepared catalyst achieves a large NH₃ yield of 1.47·10^–10mol s^–1 cm^–2 at –0.8 V and a high Faradaic efficiency of 2.17 % at –0.7 V, outperforming many other NRR electrocatalysts. SnO₂ combines a low cost, low toxicity, and high chemical stability, which makes Sn-based catalysts promising for nitrogen fixation.

• Ambient NH₃ synthesis via electrochemical reduction of N₂ over cubic sub-micron SnO₂ particle,
  Ling Zhang, Xiang Ren, Yonglan Luo, Xifeng Shi, Abdullah M. Asiri, Ting Shuai Li, Xu-Ping Sun,
  Chem. Commun. 2018.
  https://doi.org/10.1039/c8cc06524a