With the rapid growth of the global economy and the continuous increase in population, freshwater scarcity has become an increasingly critical global challenge. Consequently, the development of efficient and sustainable water purification materials has attracted considerable research interest. Solar-driven interfacial evaporation technology has emerged as a promising approach for water treatment owing to its effective utilization of renewable solar energy, in which the rational design and fabrication of photothermal materials are of paramount importance. Carbon-based nanomaterials are widely recognized as promising next-generation photothermal materials due to their broadband light absorption, high photothermal conversion efficiency, excellent stability, and tunable structural characteristics. However, the photothermal performance of conventional carbon materials is often limited by insufficient light harvesting, restricted water transport, or slow thermal response. Therefore, constructing advanced carbon-based architectures with synergistic structural and functional characteristics remains a critical challenge. In this study, a graphene@carbon nanotubes (Gr@CNTs) hybrid photothermal material was rationally designed and fabricated by in situ growing Gr nanosheets on a CNT scaffold via plasma-enhanced chemical vapor deposition (PECVD). This hybrid architecture integrates the large specific surface area of two-dimensional Gr with the porous, interconnected framework of one-dimensional CNTs, forming a unique three-dimensional network structure with high surface area and microporosity. Under 3 Sun illumination (3 kW/m²), the surface temperature of the Gr@CNTs material rapidly increased to 138.8 °C within 30 s, indicating an ultrafast photothermal response. After alkaline treatment, a strongly hydrophilic free-standing Gr@CNTs film was obtained and subsequently integrated with a polyurethane sponge to construct a composite solar evaporator. The resulting system achieved a high water evaporation rate of 3.62 kg/(m²·h) and a photothermal conversion efficiency of up to 84.0%. Compared with pristine CNTs materials, the Gr@CNTs hybrid exhibits significantly enhanced photothermal performance, faster light-response behavior, and improved operational stability. This study provides valuable insights into the rational design of advanced carbon-based photothermal materials and offers a promising strategy for efficient solar-driven evaporation and sustainable water purification applications.

Key words: graphene, carbon nanotubes, plasma enhanced chemical vapor deposition, solar vapor generation