Zinc Hydroxide-Stabilized Hydroxyl Radicals Facilitate Plasma-Driven Oxidative Nitrogen Fixation and Hydrogen Evolution

Artificial nitrogen fixation consumes 1–2% of the world’s total energy output, yet most current approaches exhibit energy conversion efficiencies (ECE) below 3%, resulting in substantial energy losses. In addition to thermodynamic constraints, a key limitation lies in the inefficient utilization of short-lived reactive intermediates, particularly hydroxyl radicals (•OH), which play a crucial role in oxidative nitrogen conversion but typically exhibit nanosecond-scale lifetimes. Herein, we demonstrate that Zn(OH)2, integrated within an in-liquid plasma nitrogen fixation system, stabilizes •OH radicals via surface adsorption, prolonging their lifetime up to 9 s. This stabilization enables sustained nitrogen oxidation at the solid–liquid interface, achieving an electrical-to-chemical ECE of 11.08%, which is the highest reported ECE to date for water-assisted nitrogen fixation. Concurrently, enhanced oxygen utilization facilitates hydrogen evolution at an industrial-grade production rate of 71.34 mmol cm–2 h–1 with a low energy consumption of 0.419 MJ mol–1. These findings offer a new strategy for managing short-lived radical species in oxidative processes and establish a promising platform for sustainable, energy-efficient nitrogen fixation coupled with hydrogen generation.