TiO2 nanoparticle coated carbon nanotube sponge with high sunlight absorption and good hydrophilicity for efficient interfacial solar-powered vapor generation

Abstract

Solar-powered interfacial vapor generation is considered a promising sustainable energy technology. We use porous TiO₂ nanoparticle coated carbon nanotube sponges (CNTS@TiO₂) as sunlight absorbers to study solar-powered interfacial vapor generation due to the extremely strong sunlight absorption of CNTs and TiO₂. The highly porous structures have great benefits to water transport in the sunlight absorbers. The formation of TiO₂ on the sidewalls of CNTs improves the hydrophilicity of the light absorber and wettability of water on the sidewalls of CNTs. The water can rapidly infiltrate the porous CNTS@TiO₂ composites. Additionally, the multiple internal reflections in “TiO₂ forest” greatly reduce the diffused reflection and thus enhance sunlight absorption. The CNTS@TiO₂ composites exhibit high sunlight absorption (96.7 %). The efficient water transport and strong light absorption in the porous light absorbers significantly improved the evaporation performance. The CNTS@TiO₂ composite with the rhombic TiO₂ shows high water evaporation rate of 3.15 ± 0.14 kg m^-2 h^-1 and energy transfer efficiency of 89.5 ± 3.9 % under 1-sun radiation.