Enhanced ammonia synthesis using surface microdischarge with metal-loaded nickel foam electrodes
Yue Feng, Yuzhuo Cai, Yaolin Wang, Tianyu Li, Santu Luo, Wen‐Peng Liang, Su‐Tao Zheng, Tao Xie, Qing‐Yuan Yang, Xue Yong, Renwu Zhou, Dingxin Liu, Xin Tu
Abstract
• The SMD reactor enhances ammonia yields by reducing NH 3 decomposition. • Ni-Co/NF enhances the formation of reactive species in gas-phase reactions. • A correlation between acid sites and ammonia yield was established. • In situ FTIR characterization was conducted under plasma activation. • The Ni-Co catalyst promotes the hydrogenation of intermediates on the surface. Non-thermal plasma (NTP) offers a promising solution for decentralized ammonia synthesis under mild conditions. However, conventional NTP approaches often suffer from limited ammonia synthesis rate and energy yield. Here, we developed a novel water-electrode surface microdischarge (SMD) reactor using nickel foam (NF) as the high-voltage electrode to enhance ammonia synthesis. Different metals were loaded onto the NF (M/NF, M=Ni, Co, Ni-Co) and grown as nanowires/nanosheets on the NF surface, significantly increasing the NH 3 synthesis rate and energy yield. Notably, when Ni-Co/NF was used as the high-voltage electrode, the highest NH 3 synthesis rate of 3390 μmol g -1 h −1 was achieved, representing a 40 % increase compared to NF alone, with an energy yield of ∼ 0.79 g kWh −1 . Plasma diagnostics and catalyst characterizations revealed that in gas-phase reactions, Ni-Co/NF facilitated the formation of active species (N 2 *, N, H α, and NH), while in surface reactions, metal loading increased the number of acidic sites, promoting the generation of NH and NH 2 intermediates on the catalyst surface. In situ plasma-coupled Fourier transform infrared (FTIR) studies further highlighted the role of the Ni-Co/NF catalyst in plasma catalytic ammonia synthesis, emphasizing their ability to enhance the hydrogenation of intermediates and the dissociation of N 2 molecules. This study demonstrates a promising SMD-based plasma catalysis strategy for sustainable ammonia production and provides valuable insights into the interactions between plasma and catalyst, advancing the understanding the N 2 hydrogenation mechanisms.