Ultrathin 1T-MoS2 Nanoplates Induced by Quaternary Ammonium-Type Ionic Liquids on Polypyrrole/Graphene Oxide Nanosheets and Its Irreversible Crystal Phase Transition During Electrocatalytic Nitrogen Reduction

Hui Mao; Yuanlin Fu; Haoran Yang; Zi-Zhao Deng; Ying Sun; Daliang Liu; Qiong Wu; Tianyi Ma; Xi-Ming Song

doi:10.1021/acsami.0c05204

Ultrathin 1T-MoS₂ Nanoplates Induced by Quaternary Ammonium-Type Ionic Liquids on Polypyrrole/Graphene Oxide Nanosheets and Its Irreversible Crystal Phase Transition During Electrocatalytic Nitrogen Reduction

ACS Appl Mater Interfaces. 2020 Jun 3;12(22):25189-25199. doi: 10.1021/acsami.0c05204. Epub 2020 May 18.

Authors

Hui Mao¹, Yuanlin Fu¹, Haoran Yang¹, Zi-Zhao Deng¹, Ying Sun¹, Daliang Liu¹, Qiong Wu¹, Tianyi Ma², Xi-Ming Song¹

Affiliations

¹ Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China.
² Discipline of Chemistry, The University of Newcastle, Callaghan, NSW 2308, Australia.

PMID: 32372649
DOI: 10.1021/acsami.0c05204

Abstract

Ultrathin nanoplates of metastable 1T-MoS₂ have been successfully stabilized and uniformly distributed on the surface of n-butyl triethyl ammonium bromide functionalized polypyrrole/graphene oxide (BTAB/PPy/GO) by a very simple hydrothermal method. BTAB as a typical kind of quaternary ammonium-type ionic liquids (ILs) played a crucial role in the formation of the obtained 1T-MoS₂/BTAB/PPy/GO. It was covalently linked with PPy/GO and arranged in a highly ordered order at the solid-liquid interface of PPy/GO and H₂O due to Coulombic interactions and other intermolecular interactions, which would induce and stabilize ultrathin 1T-MoS₂ nanoplates by morphosynthesis. The good electrocatalytic activity toward nitrogen reduction reaction (NRR) with strong durability and good stability can be achieved by 1T-MoS₂/BTAB/PPy/GO due to their excellent inorganic/organic hierarchical lamellar micro-/nanostructures. Especially, after the long-term electrocatalysis for NRR at a negative potential, metastable 1T-MoS₂ as the catalytic center undergoes two types of irreversible crystal phase transition, which was converted to 1T'-MoS₂ and Mo₂N, caused by the competitive hydrogen evolution reaction (HER) process and the electrochemical reaction between the electroactive 1T-MoS₂ and N₂, respectively. The new N-Mo bonding prevents Mo atoms from binding to other N atoms in N₂, resulting in the deactivation of the electrocatalysts to NRR after being used for 18 h. Even so, quaternary ammonium-type ILs would induce the crystal structures of transition-metal dichalcogenides (TMDCs), which might provide a new thought for the reasonable design of electrocatalysts based on TMDCs for electrocatalysis.

Keywords: 1T-MoS2; irreversible crystal phase transition; n-butyl triethyl ammonium bromide (BTAB); nitrogen reduction reaction (NRR); polypyrrole/graphene oxide (PPy/GO).