PVA-graphene coated Cu(OH)2@Cu foam intensive composite phase change materials for superior solar-thermal conversion and energy storage

The phase change materials (PCMs) are encapsulated into porous materials for collecting and storing heat energy has been widely used to overcome the intermittency of solar energy utilization. However, due to the inherent big pore structure and surface characteristics, metal porous materials are not ideal for PCM leakage-proof and slow photo-thermal response. To address these issues, A micro/nanostructured graphene-polyvinyl alcohol nanosheets/Cu(OH)2 nanowire on a three-dimensional Cu foam (CF) to fill with PCM was designed and prepared. In the composite PCM, the polyvinyl alcohol/reduced graphene oxide (PRG) films coated on Cu(OH)2@Cu foam (CCF) provided a large number of active sites for the adsorption of modified paraffin wax (PWS). The prepared composite PCM has a stable structure and high thermal conductivity properties, meanwhile, the strong PRG films play a key role in enhancing leakage-proof and stability. The results show that the enthalpy value of PRG-CCF/PWS are 160.25 J·g−1 after 200 thermal cycles; which still maintains excellent cycle thermal reliability. In addition, under the simulated solar irradiation intensity is 120 mW·cm−2, the heat storage rate and photo-thermal conversion efficiency of PRG-CCF/PWS are 1.37 J·s−1 and 90.25 %, respectively. It shows excellent photo-thermal response and uniform temperature distribution. This work provides an efficient, sustainable and affordable strategy for manufacturing high-performance composite PCM that can efficiently achieve solar energy utilization and energy management.