Nanobubbles nucleation and mechanistic analysis of ionic liquids aqueous solutions by in-situ liquid cell transmission electron microscopy

Hydrogen generation by metal-free photocatalysts and electrocatalysis of H2O is currently deemed as one of the most innovative and challenging routes to obtain sustainable green energy. Due to the high tunability, ionic liquids are expected to be new generation catalysts for H-2 production. In this work, for the first time, the dynamic behavior of nanobubbles formed from water radiolysis promoted by ionic liquids [C(n)mim][BF4] and [C(n)mim][PF6] was observed by in-situ transmission electron microscopy in liquid cells at nanoscale resolution. Aided by density functional theory and molecular dynamics simulations, we attribute the primary underlying mechanism to the activation of the hydrogen atoms of the water molecule by the anions [BF4-] and [PF6-] in the ionic liquids. We conclude that our experiment will shed light on developing new ionic liquids that may further increase the yield of hydrogen production from photolytic and electrolytic water, and consequentially promises to reduce energy consumption and promote new developments in clean energy. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the dynamic behavior of nanobubbles formed from water radiolysis promoted by ionic liquids. The researchers observed the nanobubbles using in-situ transmission electron microscopy and proposed a mechanism based on density functional theory and molecular dynamics simulations. It was found that the anions in the ionic liquids activate the hydrogen atoms of the water molecule. The findings contribute to the development of new ionic liquid catalysts to enhance the efficiency of hydrogen production from photolytic and electrolytic water, reducing energy consumption and promoting clean energy.