Solar-driven co-production of freshwater and electricity using Janus Nb2CTX/graphene aerogels

Freshwater scarcity and energy shortages stand as two of the most pressing global challenges confronting modern society. The integration of solar-driven interfacial evaporation with the hydrovoltaic effect emerges as a highly promising strategy to address both issues simultaneously. In this study, we report the development of Janus Nb 2 CT X /graphene aerogels (NGAs) specifically engineered to synergistically facilitate solar-driven seawater evaporation and hydrovoltaic power generation. The Janus NGAs were fabricated via a combination of hydrothermal reaction, freeze-drying, and surface modification techniques, yielding a three-dimensional porous architecture with distinct hydrophilic-hydrophobic asymmetry—a key structural feature for their dual-functional performance. Under 1 sun irradiation, the optimized NGA-3 sample achieved a high seawater evaporation rate of 1.64 kg·m −2  h −1 and an exceptional photothermal conversion efficiency of 86.61 %, attributed to the reduced water evaporation enthalpy (1904 kJ·kg −1 ) induced by the formation of intermediate water within the aerogel's porous structure. Meanwhile, the Nb 2 CT X MXene component enhances broadband sunlight absorption through the localized surface plasmon resonance (LSPR) effect, further boosting photothermal conversion. Concurrently, the NGAs exhibit robust hydrovoltaic performance: in NaCl solution, NGA-3 generated a stable output voltage of 147 mV under 1 sun and 236 mV under 3 sun. A peak power density of 197 μW·cm −2 was achieved in 10 wt% NaCl solution, demonstrating its adaptability to high-salinity environments. Additionally, the NGAs maintain excellent salt resistance and long-term operational stability. The synergistic integration of efficient photothermal conversion and electricity harvesting in the Janus NGAs offers a viable solution to alleviate global freshwater and energy pressures.