A highly efficient antibacterial solar-thermal evaporator based on waste tea leaves for water evaporation and thermoelectric generation

Abstract

Utilizing solar-driven interfacial water evaporation technology for desalination is one of the effective approaches to alleviate freshwater scarcity. However, practical applications face challenges such as high production costs of solar-thermal materials and poor resistance to microbial contamination, which hinder long-term development. Herein, we developed a strategy for preparing highly efficient antibacterial solar-thermal evaporator by using waste Maojian tea rich in sunlight-absorbing pigments and antibacterial ingredients. The antibacterial capability of this solar-thermal evaporator mitigates microbial contamination and corrosion issues, extends the service life of the evaporator, and improves the water quality of evaporated water. Under 1 kW m⁻² mimic solar radiation, water evaporation rate reaches 1.36 kg m⁻² h⁻¹. When integrated with a thermoelectric module, it enables simultaneous water evaporation and thermoelectric power generation through temperature differences, yielding an output voltage of 50 mV. Results demonstrate that this strategy for constructing highly efficient antibacterial solar-thermal hydrogels from waste tea leaves provides an effective solution to address the limitations of solar-thermal materials in antibacterial performance. It represents a green, low-cost, and highly efficient sustainable desalination technology.