Understanding the Wettability of Graphene Coatings: Insights, Measurements, and Implications for Diverse Applications

Graphene's (GR) wettability is a contentious subject marked by conflicting reports. Some studies claim superhydrophobicity with up to 150° contact angles indicating limited wettability. Conversely, other research suggests factors like surface roughness, contaminants, and lattice defects modify GR's wettability, revealing moderate hydrophilicity in defect-free GR. Persistent disagreements center around the impact of GR production processes, substrate interactions, and environmental factors. This paper addresses the controversy by scrutinizing wetting measurement techniques and sample preparation. We present a comprehensive framework for sample preparation and characterization for a few GR layers. Key findings highlight the significance of sample preparation and the identification of Atomic Force Microscopy (AFM) and Vibrational Sum Frequency Generation (VSFG) spectroscopy as particularly valuable techniques for assessing GR wettability. These insights contribute to tailored GR-based applications, from surface coatings to catalysis and energy storage.