Pressure-temperature dependence of the water-graphene interfacial tension, with insights into cavitation under negative pressure

We present the first pressure-temperature diagram of the interfacial tension γ ( T , P ) of water at a graphene surface, obtained from molecular dynamics simulations over a wide range of temperatures (240-300 K) and pressures, including strongly negative values. We find that, in contrast to liquid-liquid interfaces, the water-graphene interfacial tension increases with pressure. A microscopic analysis based on the local surface tension reveals that this behavior originates from the dominant contribution of repulsive intermolecular interactions, whose reinforcement under compression enhances interfacial stress anisotropy near the rigid hydrophobic surface. The temperature dependence highlights the competing roles of thermal fluctuations and mechanical confinement in controlling interfacial structure and tension. By extending the calculations into the metastable negative-pressure regime, we are able to follow the evolution of interfacial tension up to the limit of mechanical stability, thereby capturing the approach to cavitation. These results establish a microscopic framework for understanding the thermodynamic control of solid–liquid interfacial tension.