Design Principles and Insights into the Liquid-Phase Exfoliation of Alpha-MoO3 for the Production of Colloidal 2D Nano-inks in Green Solvents

The interest in layered 2D nanomaterials has witnessed an impressive growth in the last years, bringing to the discovery of many new species and methods for their preparation. The liquid-phase exfoliation (LPE) of crystalline bulk powders is certainly the most suitable method for scaled-up production, allowing also the convenient access to solution processing techniques for the direct utilization of the produced 2D material colloidal inks. Given the large number of reports on LPE processes for different 2D materials, today, it is necessary to specifically define the results of similar investigations, so as to provide the scientific community with clear guidelines for identifying design rules and applying standardized procedures. In this work, we present a systematic study on the LPE process for alpha-MoO3, a stable high band gap semiconductor, which in its 2D form has been employed for many purposes, ranging from catalysis to energy/optoelectronic devices and sensing. We investigate the effect of different low-toxicity solvents and instruments for its LPE and provide new insights into the structural and electronic properties of the resulting 2D nano-inks in a joint experimental-computational effort, which will represent a solid source of information for the future implementation of liquid-dispersed layered alpha-MoO3 nanosheets in different fields.