High-Efficiency Photothermal Water Evaporation under Low-Intensity Sunlight Using Wood Biochar Monolith.

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Solar water evaporation is crucial for the global water cycle and freshwater production.
• Current photothermal materials for solar desalination are inefficient and costly.
• Efficient solar absorbers are needed to convert photons to thermal energy for enhanced water evaporation.

Purpose of the Study:

• To develop a novel, efficient, and low-cost photothermal material for solar water evaporation.
• To investigate the performance of wood biochar monoliths (WBMs) in solar desalination.
• To understand the mechanisms behind the high efficiency of WBMs.

Main Methods:

• Wood was carbonized via pyrolysis at 1000 °C to create biochar.
• The biochar was steamed at high pressure to form a wood biochar monolith (WBM).
• The light-to-vapor efficiency of WBM was tested under low light intensity (193 W/m²).

Main Results:

• Maple WBM demonstrated a light-to-vapor efficiency exceeding 100% under low light intensity.
• High efficiency is attributed to facilitated water transport in the WBM's porous structure and reduced evaporation enthalpy.
• WBM exhibits high broadband sunlight absorptivity and can harvest thermal energy from surrounding water.

Conclusions:

• Wood biochar monoliths represent a breakthrough in photothermal materials for solar desalination.
• The developed WBM offers a sustainable, cost-effective solution for freshwater generation.
• This technology has potential for deployment in remote areas for water desalination and humidification.