A Focus on our PhD Students – Marta Alcaraz Megias

My first incursion in science was during my last years in high school, when I obtained a scientific summer scholarship to start getting in touch with science in a laboratory in Gran Canaria (Spain). Since then, I have had a growing interest and enthusiasm in scientific research. I earned my degree in Chemistry at the University of Granada (Spain), where I was born. My undergraduate dissertation involved porous crystalline materials based on clusters coordinated to organic ligands, Metal-Organic Frameworks (MOFs), for capturing toxic gases such as SO 2 and CO2 . When I finished my Chemistry degree, I moved to Valencia to undertake my Master degree in Organic Chemistry at the University of Valencia. During this period, I carried out research for my Master thesis in the Institute of Molecular Science (ICMol), which enabled me to learn to synthesize and characterise different organic ligands.

One year later, in 2019, I had the great opportunity of starting my PhD in Nanotechnology and Nanoscience in the same research Institute, under the direction of Dr. Gonzalo Abellán Sáez. The topic of my thesis is the chemistry and interface control of a novel family of layered materials from group-15 of the Periodic Table, called Pnictogens (P, As, Sb and Bi). 2D-Pnictogens have gained increasing attention due to their semiconducting behaviour, with thickness-dependent band gaps that can be modulated by strain, doping or chemical functionalisation, which can be useful for fabricating optoelectronic devices. Additionally, these 2D -Pnictogens offer unique photonic, catalytic, magnetic, and electronic properties. Within this chemical group, antimonene is a monoatomic 2D material with a buckled structure showing exceptional physicochemical properties, suggesting promising applications in cutting edge technologies. Although some of its theoretically-predicted remarkable properties have already been experimentally demonstrated, others remain a challenge to corroborate because of the absence of a suitable synthetic method to produce the required high-quality material. Antimonene can be isolated using top-down and bottom-up approaches. On the one hand, top-down methods such as micromechanical or liquid phase exfoliation have demonstrated the ability to produce poorly-defined hexagonal antimonene nanoflakes. On the other hand, bottom-up methods, as well as molecular beam epitaxy and van der Waals epitaxy approaches, have led to high-quality antimonene flakes but are not suitable for large-scale synthesis. Another bottom-up approach has been recently reported, involving a solutionphase synthesis of well-defined hexagonal few-layer antimonene via anisotropic growth, which has facilitated large-scale production of this material. In this context, our work is focused on optimising the synthetic parameters for the production of high quality few-layer antimonene hexagons, and their implementation in a large-scale manufacturing process under continuous-flow conditions to pave the way for optoelectronic device fabrication. Some of our results were presented at the 7 th ISGS Online Summer School and I had the pleasure of being awarded the 2 nd ePoster Prize.

(HR)STEM images of Antimonene

My future work will be centred on producing, via wet chemistry, other novel 2D-Pnictogens materials, such as bismuthene, to control the thickness, lateral dimensions, crystallinity, and/or surface properties. As a continuation, the next step will be to functionalize the interface of these 2Dmaterials through both covalent and noncovalent interactions in order to modulate their electronic properties, such as band gap, or improve their stability under atmospheric conditions.