Enhanced performance and thermoelectric properties of composite electrothermal coatings driven by photovoltaics

Electrothermal coatings have great application potential for building heating. However, conventional carbon-based electrothermal coatings feature inferior thermal stability and are incompatible with photovoltaic low-voltage heating systems. Herein, waterborne carbon-based electrothermal coatings matched with photovoltaic low-voltage power supply are prepared with graphene filter cake (GFC) and carbon nanotube slurry (CNS) as conductive fillers and acrylic resin (AR) as binder. The effects of component loadings on electrothermal behaviors are systematically explored. By synergistically building continuous 3D conductive networks using dual carbon fillers, efficient and stable electrothermal performance is realized under low photovoltaic voltage, overcoming slow heating and poor thermal durability of single-carbon-filled coatings. The optimal formulation contains 20 wt% graphene filter cake, 26.7 wt% carbon nanotube slurry and 21.7 wt% acrylic resin. The corresponding coating achieves a steady-state peak temperature of 68.72°C and a heating rate of 6.3°C/min (90.91% higher than the baseline), with a thermal conductivity of 0.95 W/(m·K). Under photovoltaic low-voltage operation, the coating quickly maintains the mean radiant temperature of enclosed space at 36°C, and demonstrates excellent storage stability, thermal aging resistance and adhesion.