Integrated HTO@fiber interfacial evaporator for concurrent photovoltaic cooling, lithium extraction, and desalination

The operational efficiency and long-term reliability of photovoltaic (PV) panels are significantly compromised by overheating. To alleviate this issue, this work pioneered a tri-functional hybrid system addressing PV overheating, freshwater scarcity, and lithium extraction challenges. By laminating hydrous titanium oxide (HTO)-functionalized fibers (HTO@fiber) onto PV panels, the integrated system simultaneously enables: (i) evaporative cooling reducing PV temperatures by up to 16.4 °C under one-sun illumination, thereby achieving a peak power output enhancement of 12.5 % through suppressed carrier recombination and widened semiconductor bandgaps; (ii) targeted lithium extraction leveraging evaporation-induced interfacial concentration polarization and waste-heat-activated endothermic adsorption kinetics, achieving optimal lithium cation uptake capacities of 17.81 mg·g −1 with high selectivity in real brines, conforming to pseudo-second-order chemisorption models; and (iii) sustainable desalination yielding freshwater at 1.680 kg·m −2 ·h −1 under one sun. Outdoor validation over five days demonstrated practical viability with daily averages of 5.79 kg·m −2 freshwater production and up to 4.75 g·g −1 lithium cation recovery, underpinned by HTO@fiber's stability (<10 % capacity loss after 5 cycles) and efficient capillary transport. This integrated paradigm converts PV operational liabilities — thermal dissipation and land footprint — into synergistic resource recovery, establishing a scalable approach to enhance solar infrastructure economics while advancing water-energy-lithium nexus sustainability.