Graphene–Carbon Composites for Solar and Low‐Voltage Powered Efficient Interfacial Evaporation

Abstract Nanocarbon materials have great potential for sustainable energy harvest and energy utilizations, such as solar thermal stream generation, and interfacial evaporation. However, the evaporation rate is far too low for practical applications. The technologies are not ready yet for industries requiring rapid, energy‐efficient, and low‐cost evaporation processes such as distillation and sterilization. A flexible ultrathin graphene–carbon cloth (CC)‐based carbon–carbon composites is prepared by in situ electrochemical reduction of graphene oxide. The carbon–carbon composite materials demonstrate high performance in photothermal evaporation; more importantly, all carbon‐based devices can also be operated as low‐voltage Joule heating elements in wide temperature range up to 389 °C. Even when a very low voltage of 3 V is applied, the graphene–CC heater can reach a very high heating speed up to 112 °C s –1 , and a steady‐state temperature up to 292 °C within 10 s only. The low‐voltage heater promises to be the most effective solution for high‐speed interfacial evaporation since its evaporation rate can reach up to 45.87 kg m −2 h −1 , enhanced by one order of magnitude compared to the best solar power photothermal seawater desalination devices ever reported.