7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Green chemical pathway of N2 fixation: Perspectives from plasma modellingJungmi Hong1, Tianqi Zhang1, Jing Sun2,3, Hassan Masood2, Emma C. Lovell2, Renwu
Zhou1,3, Liguang Dou4, Shuai Zhang4, Rusen Zhou1,5, Bryony Ashford6, Tao Shao4, Anthony B.
Murphy6, Kostya (Ken) Ostrikov5, Ali Rouhollah Jalili2, Rose Amal2 and Patrick J. Cullen1
1
The University of Sydney, 2 University of New South Wales, 3 Xi’an Jiaotong University,4Institute of Electrical Engineering, Chinese Academy of Sciences,
5Queensland University of Technology, 6 Manufacturing, CSIRO
e-mail (speaker): jungmi.hong@sydney.edu.au
Alternative sustainable N2 fixation under ambientconditions that can be operated with renewable energy
sources and feedstocks is globally sought to replace theconventional Haber–Bosch process. Plasma catalysis isreceiving increasing attention as a green technology forthe efficient synthesis of ammonia and also NOx.
However, the current implementation of plasma catalysisof N2 fixation application still faces challenges, especiallythe extensive energy usage for H2 formation prior to NH3production, low energy efficiency and importantly thelack of understanding about the underpinned mechanism.
In this study, we compare different green chemical
pathway of plasma catalysis of ammonia and NOx and its
effective storage in water using plasma chemistrymodelling.
The zero-dimensional plasma chemistry modelling wasperformed using open source ZDPlaskin[1] combined with
Boltzmann equation solver BOLSIG+[2] to understanddifferent mechanisms of NH3 and NOx production in
N2/H2O and air plasma system with and without catalyst.
The model provides the explanations about the importantrole of surface reactions to enhance the reactivity of thesystem at different plasma conditions.
Figure 1 shows the examples of plasma chemistrymodelling for ammonia synthesis on SiO2 surface in
N2/H2O plasma based on activation energy calculationfrom DFT study.[3] The quenching effect of vibrationallyexcited N2(i) species by water molecules was considered
to be the important difference to cause the limitations ofammonia synthesis in N2/H2O system not only thecompeting oxidation reactions. Therefore, the role ofcatalytic surface reactions becomes even more crucial toimprove production rate and energy efficiency and as well
as relatively high gas temperature condition enabled byhigh density electrons. As in a similar approach, NOx
synthesis using Graphene oxide/TiO2 catalyst was also
investigated[4] by integrating accurate activation energies
from DFT calculations for each oxidation and dissociation
steps.
Further discussions will be presented regarding theimportant role of surface reactions to circumvent thecurrent limitations of plasma catalysis in different N2
fixation process.
References[1] S. Pancheshnyi et al., (www.zdplaskin.laplace.univtlse.fr), (2008)[2] G. J. M. Hagelaar and L. C. Pitchford, Plasma
Sources Sci. Technol. 14, 722-733 (2005)[3] J. Hong et al., Green Chem., 24, 7458-7468 (2022)[4] J. Sun et al., Chem. Eng. 469, 143841 (2023)

Figure 1 (a) Summary of DFT calculation results for SiO2 surface, (b) density profile of important gas phase species in
N2/H2O plasma system, comparison of (c) gas composition at different power density and (d) energy efficiency ofmodel and the measurement, and important (e)production and (f)loss mechanism of NH 3 in N2/H2 and N2/H2O system