Ion transport properties of atomically-thin crystals: Novel proton transport, ion-exchange and selectivity properties.

  • Lucas Mogg

Student thesis: Phd


Dedication in this thesis has been made to the study of ion transport both through (and within) atomically-thin crystals. We explore how protons over chloride ions selectively passage through 2D materials such as hexagonal boron nitride (hBN). Next, we reveal how protons can permeate through 5 angstrom-wide channels in proton-exchanged muscovite mica and vermiculite. Finally, we report an enhanced ion-exchange rate in few-layer clays, as well as imaging of their ion distribution to high levels of detail. An introduction to the topics and research conducted is first presented. Next, three background sections that equip the reader with sufficient knowledge to understand the results presented are given. The first background section introduces the topic of ion transport in a broader sense, covering the fundamental driving forces as well as more focused areas including mechanisms of ion-selectivity. Next, the second background chapter provides an overview and literature review of the nascent field of proton-transport through 2D materials, both from an experimental and a theoretical perspective. The final two background chapters present an overview of ion-exchange and then experimental techniques are provided. The next three chapters contain results of work in journal format as either accepted publications or as a submitted manuscript. The first results chapter contains work on proton-selectivity through 2D materials. The second results chapter is that of a study regarding proton-transport through ion-exchanged mica. In the last results chapter, we present an ion-exchange study of few layer mica and clay. We then finally conclude the thesis and discuss future directions and outlooks. The implications and significance of our findings presented in this thesis are as follows. We anticipate that we have contributed to the debate on how protons permeate through the lattice of 2D materials. We ascribe the proton-selective nature of hBN and graphene to that of permeation through the intrinsic lattice. Secondly, we have reported a new class of proton conducting membrane, that of proton-exchanged few-layer mica. This membrane can be operated at high (>200 C) temperatures at an areal conductivity exceeding 10 Scm-2. We anticipate that scaling of these membranes may be possible, in the same fashion that CVD graphene is scalable. Lastly, we have reported enhanced ion-exchange rates for few layer clays and their ion-distribution in unprecedented detail. This opens up a new avenue for researchers to explore ion-exchange effects in clays and other 2D exchanging materials from both a fundamental and applications perspective.
Date of Award1 Aug 2021
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorAndre Geim (Supervisor), Irina Grigorieva (Supervisor) & Marcelo Lozada Hidalgo (Supervisor)


  • TEM
  • Graphene
  • Ion Selectivity
  • Vermiculite
  • 2D Materials
  • Ion Exchange Membranes
  • Proton Conductivity
  • Ion Exchange
  • Ion Transport
  • Clay

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