A Hydrogenated Metal Oxide with Full Solar Spectrum Absorption for Highly Efficient Photothermal Water Evaporation
Qing Zhu, Ke Ye, Wen Zhu, Wenjie Xu, Chongwen Zou, Li Song, Edward Sharman, Linjun Wang, Shunyu Jin, Guozhen Zhang, Yi Luo, Jun Jiang
Abstract
Searching for cost-effective photothermal material that can harvest the full solar spectrum is critically important for solar-driven water evaporation. Metal oxides are cheap materials but cannot cover the full solar spectrum. Here we prepared a hydrogenated metal oxide (H1.68MoO3) material, in which H-doping causes the insulator-to-metal phase transition of the originally semiconductive MoO3. It offers a blackbody-like solar absorption of ≥95% over the entire visible-to-near-infrared solar spectrum, owing to its unusual quasi-metallic energy band, and high solar-to-heat conversion rate due to quick relaxation of excited electrons. Using a self-floating H1.68MoO3/airlaid paper photothermal film, we achieved a stable and high water vapor generation rate of 1.37 kg m–2 h–1, a superb solar-to-vapor efficiency of 84.8% under 1 sun illumination, and daily production of 12.4 L of sanitary water/m2 from seawater under natural sunlight. This thus opens a new avenue of designing cost-effective photothermal materials based on metal oxides.