TiVCTX/carbon nanotubes/graphene aerogels for simultaneous power and steam cogeneration

Abstract

The ongoing global crisis regarding energy and water shortages has spurred the innovation of multifunctional materials that integrate clean energy generation and seawater desalination technologies. This research introduces TiVCT_X MXene/carbon nanotubes/graphene aerogels (TCGAs), a groundbreaking composite engineered for concurrent hydrovoltaic energy production and solar-driven steam generation. Fabricated successfully through hydrothermal and freeze-drying methods, TCGAs feature a porous nanostructure, high specific surface area, remarkable hydrophilicity, and exceptional solar absorption capabilities. When exposed to 1-sun irradiance in a 3.5 wt% NaCl solution, TCGAs generate an output voltage of 90 mV and a current of 50 μA; this output rises to 160 mV under 3-sun conditions, due to improved ion transport and enhanced photothermal effects. Optimization of the electrolyte indicates that LiCl solution outperforms NaCl and CaCl₂: at 3.5 wt% LiCl under 1 sun, TCGAs produce 112 mV and 63 μA, while at 10.0 wt% LiCl under 3 sun, they achieve 230 mV with a power density of 4.4 μW cm⁻². For desalination purposes, TCGAs achieve a seawater evaporation rate of 1.0 kg m⁻² h⁻¹ (with a conversion efficiency of 61.5 %) under 1 sun, increasing to 4.72 kg m⁻² h⁻¹ (73.4 % efficiency) under 3 sun. Notably, TCGAs demonstrate exceptional cyclic stability in both energy generation and desalination, along with outstanding superior salt resistance and self-desalting properties. These findings position TCGAs as a promising candidate for sustainable energy-water co-generation systems, providing a practical solution to the interconnected issues of energy deficiency and water scarcity.