Improved NRR electroactivity by MoS2-SnS2/poly(zwitterionic liquids)/polypyrrole/graphene oxide

Ammonia (NH₃) is an important chemical feedstock, widely used for synthesizing chemical products in industrial production. However, the traditional Haber-Bosch process for reducing N₂ to produce NH₃ requires harsh synthetic conditions and causes high fossil energy consumption and serious environmental pollution.

Electrochemical nitrogen reduction reaction (NRR) under ambient conditions has been considered a promising sustainable clean energy technology for the production of NH₃, whose essential core for practical application is focused on exploring the NRR electrocatalysts with high efficiency, low cost and easy preparation.

Transition metal dichalcogenides (TMDCs), with abundant reserves and low cost, present outstanding electrocatalytic activity due to polytropic crystal structures and phase compositions, controllable morphologies and adjustable defect engineering, which make them an ideal alternative for replacing precious metals. Therefore, it is of great significance for effectively regulating TMDCs structure to improve its electrocatalytic NRR activity.

Recently, a research team led by Prof. Tianyi Ma from RMIT University (Australia) and Prof. Xi-Ming Song from Liaoning University (China) reported the inorganic/organic hierarchical nanostructures used for electrocatalytic NRR, where the unique MoS₂-SnS₂ heterogeneous nanoplates have in-situ grown on poly(3-(1-vinylimidazolium-3-yl)propane-1-sulfonate) (PVIPS) functionalized polypyrrole/graphene oxide (PPy/GO) by the interfacial induced effect.

The obtained MoS₂-SnS₂/PVIPS/PPy/GO can serve as electrocatalysts, exhibiting good NRR performance by the synergistic effect. The semi-conducting SnS₂ limits the surface electron accessibility for suppressing HER process of 1T'-MoS₂, while metallic 1T'-MoS₂ efficiently improves the NRR electroactivity of SnS₂ by the creation of Mo–Sn–Sn trimer catalytic sites.

Irreversible crystal phase transition takes place during the NRR process. Partial 1T'-MoS₂ and SnS₂ electrochemically react with N₂, and irreversibly convert into Mo₂N and Sn_xN_z due to the formation of Mo−N and Sn−N bonding. Meanwhile, partial SnS₂ has been irreversibly evolved into SnS due to the reduction by the power source in the electrochemical system. The results were published in Chinese Journal of Catalysis (doi.org/10.1016/S1872-2067(21)63944-X).

More information:
Hui Mao et al, Improved nitrogen reduction electroactivity by unique MoS2-SnS2 heterogeneous nanoplates supported on poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide, Chinese Journal of Catalysis (2022). DOI: 10.1016/S1872-2067(21)63944-X

Provided by Chinese Academy of Sciences