Electrochemical Control of Charge Current Flow in Nanoporous Graphene

Isaac Alcón,Nick Papior,Gaetano Calogero,Mads Brandbyge

doi:10.1002/adfm.202104031

Abstract

AbstractDuring the last decade, on‐surface fabricated graphene nanoribbons (GNRs) have gathered enormous attention due to their semiconducting π‐conjugated nature and atomically precise structure. A significant breakthrough is the recent fabrication of nanoporous graphene (NPG) as a 2D array of laterally bonded GNRs. This covalent integration of GNRs could enable complex electronic functionality at the nanoscale; however, for that, it is crucial to externally control the electronic coupling between GNRs within NPGs, which, to date, has not been possible. Using quantum chemical calculations and large‐scale transport simulations, this study demonstrates that such control is enabled in a newly designed quinone‐NPG (q‐NPG) thanks to its GNRs inter‐connections based on electroactive para‐benzoquinone units. As a result, the spatial distribution of injected currents in q‐NPG may be tuned, with sub‐nanometer precision, via the application of external electrostatic gates and electrochemical means. These results thus provide a fundamental strategy to design organic nanodevices with built‐in externally tunable electronics and spintronics, which is key for future applications such as bio‐chemical nanosensing and carbon nanoelectronics.

Highlights

During the last decade, on-surface fabricated graphene nanoribbons (GNRs) up on-surface synthesis.[1,2] designed organic molecules are deposited have gathered enormous attention due to their semiconducting π-conjugated on metallic substrates where they selfnature and atomically precise structure
Using quantum chemical calculations and large-scale transport have been fabricated in this way, such simulations, this study demonstrates that such control is enabled in a newly designed quinone-nanoporous graphene (NPG) (q-NPG) thanks to its gates and electrochemical means. These (GNRs) inter-connections based on electroactive para-benzoquinone units
In this work we propose the quinone-NPG (q-NPG), where GNRs are connected with para-benzoquinone units, as a platform for electrochemically controlled charge transport

Summary

Materials Design and Characterization

In this work we propose the quinone-NPG (q-NPG), where GNRs are connected with para-benzoquinone units (top panel in Figure 2a), as a platform for electrochemically controlled charge transport. Such spin polarization does not appear in the analogous aryl-connected NPG under the same applied gates (see Figure S4, Supporting Information) and so this effect may be exclusively associated to the quinoidal functionality. This spin polarization is consistent with the partial reduction (i.e., electron addition) of the quinoidal aryl rings which, as schematically represented, acquire an open-shell (i.e., radical) character This result is in agreement with other studies which have reported spin polarization (open-shell character) of quinoidal derivatives by means of N-doping,[47,48,49] electrochemical reduction,[50] and surface chemisorption.[51] The magnetic coupling between the spin-polarized quinone units is rather weak both along the x and y directions, as shown with the nearly energetic degeneracy between the ferromagnetic solution with other antiferromagnetic spin configurations (see Figure S5, Supporting Information). Such an appealing spin-filtering effect arises from the electronic “opening” of the quinone bridges in the spin-up channel, while maintaining the QI blockade for spin-down currents

Electrochemistry

Conclusion

Experimental Section

Data Availability Statement