A scalable phase-change bionanocarbon hybrid-bonded paper membrane for simultaneous hygroscopic buffering, high thermal effusivity, and ventilation energy management

The integration of phase-change materials (PCMs) with active energy recovery systems has emerged as a promising strategy for low-carbon thermal energy management due to their low cost, high energy density, and favorable phase-transition characteristics. Yet, they typically lack the capacity to effectively transfer heat that exceeds the dissipation capacity of spatially constrained environments, as well as in simultaneously managing moisture variation, along with environmental and stability concerns, which hinder their application in high-precision thermal buffering. Conventional composites partially mitigate these issues but fail to balance energy storage density and heat transfer efficiency or integrate eco-friendly energy recovery. Here, we propose a sustainable multidirectional paper membrane composite (SWGD-VP) with graphene-interfaced biocarbon phase-change aerogel, integrated into a paper membrane for synchronous heat storage, enhanced thermal effusivity, and hygrothermal energy recovery ventilation. The bionanocarbon forms an interconnected conductive network with desirable morphology, wherein graphene is anchored onto a porous biochar framework, establishing an interfacial coupling that promotes thermal transport and structural stability. The aerogel reveals an 11.4% increase in enthalpy over the bulk biochar/PCM composite and outstanding thermal diffusivity enhancements of 179.5%, 111.8%, and 32.3% over pristine PCM, biochar/PCM, and graphene/PCM, respectively, while retaining 94.2% of its mass after heating. The resulting SWGD-VP hybrid membrane demonstrates nearly threefold higher thermal conductivity, a steady-state temperature distribution approaching 40 °C over 2 h, and a thermal effusivity of 766.7 J·m −2 ·K −1 ·s –1/2 , enabling efficient heat exchange under dynamic conditions. Additionally, it exhibits high vapor permeability (S d < 1 m), satisfying ASTM E96 and ISO 12572 standards. This work presents a viable and environmentally friendly strategy for the deployment of smart phase-change hybrid membranes for ventilation systems with simultaneous heat and moisture management.