Reinforced Volumetric Discharge by Tuning Permittivity and Spatial Scale Intensified Pulse Current for Efficient CO₂ Reduction

Abstract

Nonthermal plasma (NTP) is an energy-efficient method for CO 2 reduction to achieve CO 2 conversion into highvalue-added products. However, the low conductive properties and restricted spatial characteristics of conventional dielectric packings confine discharge currents, rendering volumetric discharge impeded, which limits electron collisional ionization and CO 2 conversion. Herein, we propose a novel strategy for volumetric discharge reinforcement aiming to intensify pulse current by modulating the permittivity and spatial scale of hollow cylindrical dielectric membranes (HCDMs), thereby improving the CO 2 hydrogenation process. In a self-designed dielectric barrier reactor, a silicon carbide HCDM with a high permittivity of 1541 and a large streamer space ratio of 0.4 was fitted, resulting in ∼3 times CO 2 conversion (62.4%) and ∼10 times energy efficiency (1.48 mol/kW h) compared to conventional alumina-stacked packings with a permittivity of only 7.1 and a streamer space ratio of zero. Due to its long lifetime and high performance, the preferred HCDM contributes more to the sustainability of NTP CO 2 reduction. Its high inductivity and large spatial scale enhance the peak pulse current from 21 to 80 mA, significantly increasing the electron density and electric field. The vibration excitation generated by electron impact, enabling high-density H•, O•, CO 2 + , and CO formation, is more intense. This study provides a new pathway for efficient CO 2 reduction utilizing NTP, which offers the possibility of sustainable greenhouse gas CO 2 recycling.