Multi-hollow dielectric barrier discharge plasma: An energy-efficient strategy towards mild ammonia synthesis

Abstract

Renewable-driven non-thermal plasma (NTP) technology provides a potentially sustainable alternative for ammonia (NH₃) production. Nonetheless, energy efficiency remains a critical bottleneck in NTP reactors. Herein, we propose a multi-hollow dielectric barrier discharge (MDBD) plasma reactor to realize nitrogen hydrogenation towards ambient NH₃ synthesis, with the physicochemical characteristics systematically explored for the first time. Transient discharge dynamics were captured by electrical characterization, meanwhile the active intermediate species and the low-temperature properties of MDBD were unveiled by optical spectrum diagnosis. Effects of feed gas, flow rate and specific energy input (SEI) on reaction activity were investigated in terms of energy efficiency (EE) and energy consumption (EC). Notably, remarkable reaction efficacy was realized under low driving powers. For a fully-developed 'steady' discharge, an EE of 1.32 g/kWh and an EC of 46.44 MJ/mol could be attained at 3.20 W. Under a pulse-like fluctuating 'flicker' mode at merely 1.15 W, the EE and EC were improved to 1.78 g/kWh and 34.35 MJ/mol, respectively, further highlighting the energy-effectiveness of MDBD. This work provides a novel approach for energy-efficient, environmental-friendly and distributed NH₃ production.