Efficient catalyst-free N 2 fixation by water radical cations under ambient conditions.

The growth and sustainable development of humanity is heavily dependent upon molecular nitrogen (N 2 ) fixation. Herein we discover ambient catalyst-free disproportionation of N 2 by water plasma which occurs via the distinctive HONH-HNOH +• intermediate to yield economically valuable nitroxyl (HNO) and hydroxylamine (NH 2 OH) products. Calculations suggest that the reaction is prompted by the coordination of electronically excited N 2 with water dimer radical cation, (H 2 O) 2 +• , in its two-center-three-electron configuration. The reaction products are collected in a 76-needle array discharge reactor with product yields of 1.14 μg cm -2 h -1 for NH 2 OH and 0.37 μg cm -2 h -1 for HNO. Potential applications of these compounds are demonstrated to make ammonia (for NH 2 OH), as well as to chemically react and convert cysteine, and serve as a neuroprotective agent (for HNO). The conversion of N 2 into HNO and NH 2 OH by water plasma could offer great profitability and reduction of polluting emissions, thus giving an entirely look and perspectives to the problem of green N 2 fixation.