Utilizing the abundant and renewable solar energy to address the global energy shortage and water scarcity is promising. Great effort has been devoted to photothermal conversion for its typically full-spectrum utilization and high efficiency. Here, the coral-like micro/nanostructure was fabricated on an aluminum sheet by a facile laser direct writing technology. The nanocluster and microscale branches of corals endowed this black aluminum with broad-band plasmonic absorption and rapid heat transfer from the light absorption region to substrate. The black aluminum achieved ultrahigh solar absorbance of over 92.6% (>95.1% in the visible range) and excellent light heating ability (>90.6 °C under 1.0 sun). With good photothermal properties, this plasmonic absorber was used in a state-of-the-art eight-layer membrane distillation system, producing a water yield of up to 2.40 kg m-2 h-1 and a high solar conversion efficiency of 166.5% under 1-sun irradiation. Photothermal electricity was also achieved based on this system with a thermoelectric generator, with a water yield of 0.89 kg m-2 h-1 and a maximum electrical power output of 7.21 μW cm-2 under 1.0 sun. Considering the excellent performance of the plasmon-enhanced black aluminum, this work provides an alternative and feasible route toward high-efficient utilization of the solar energy.
Keywords: black aluminum; coral-like micro/nanostructures; laser microfabrication; multistage membrane distillation; photothermal/electric conversion; plasmonic effect.