Physics Seminar : Aitor Mugarza

Atomically precise nanoporous graphene: from synthesis towards applications in chemical sensing

Abstract

A plethora of atomically precise graphene nanostructures with diverse functionalities have been synthesized in the last decade following different on-surface synthesis strategies. However, despite significant progress in synthesizing one-dimensional homostructures, advancing towards greater structural complexity by introducing functional groups and heteroatoms, fabricating heterostructures, or extending surface-assisted strategies to two-dimensional structures, still presents significant challenges. Regarding the application of on-surface synthesized graphene nanostructures, attempts to transfer them to devices or even expose them to ambient conditions have been seldom and revealed many challenges related to chemical stability, post-transfer quality, and device fabrication.

In this presentation, I will discuss different strategies that we have developed to address each one of these challenges. Firstly, I will introduce our method for synthesizing 2D nanoporous graphene, where the long-range order is achieved through the sequential growth and coupling of 1D building blocks [1]. Subsequently, I will focus on two modular approaches leading to more intricate nanoporous structures. The first involves molecular engineering of coupling bridges, demonstrating tunability in quantum electronic coupling and in-plane electronic anisotropy through the introduction of flexible phenyl groups [2]. The second relies on a sequential interdigitation method, where the first 1D ribbon component defines a long-range ordered scaffold for the intercalated growth of a functionalized second component. This method serves a dual purpose by enabling simultaneous doping and the generation of ultranarrow lateral heterostructure superlattices [3]. Finally, I will present our latest efforts to advance from the on-surface synthesis of graphene nanostructures towards their application in chemical sensing devices. We carried out fundamental studies of the gas-analyte interactions and of the stability in different environmental conditions by using near ambient pressure X-ray photoelectron Raman spectroscopies. The fabrication of field-effect transistor devices and their characterization is carried out for channel lengths that are far beyond the size of the crystal domain, reaching the sensing area characteristic of sensing devices while maintaining on/off ratios comparable to single ribbon FETs. Altogether, these studies define a feasible path towards the integration of on-surface synthesized nanoporous graphene into chemical sensors.

References:

[1]       C. Moreno et al., Science 360 (2018) 199–203.

[2]       C. Moreno et al., J. Am. Chem. Soc. 145 16 (2023), 8988–8995.

[3]       M. Tenorio et al., Adv. Mater. (2022) 2110099.

About the speaker

Prof. Aitor Mugarza graduated in physics in 1997, before earning his PhD in the same field in 2002, both at the Euskal Herriko Unibertsitatea (University of the Basque Country). He was awarded a Marie Curie Fellowship to work as a postdoctoral scientist at the Lawrence Berkeley National Laboratory (USA) and the Institut de Ciència de Materials de Barcelona (ICMAB). He joined the former Catalan Institute of Nanotechnology in 2007 with a Ramón y Cajal Fellowship. In 2013 he became group leader of the Atomic Manipulation and Spectroscopy Group at the recently constituted ICN2. He has been an ICREA Research Professor since 2015.

His research activity is based on the study of quantum electronic and magnetic phenomena at the nanoscale and the development of strategies for their manipulation with atomic precision. By combining scanning tunnelling microscopy techniques with spectroscopy using synchrotron radiation, he correlates microscopic phenomena to macroscopic observables for the characterisation and design of new materials and devices. He is currently focused on novel materials including molecular and graphene nanostructures, topological insulators and other 2D materials with strong spin-orbit interactions.