Manganese Oxide Hydrogel for Efficient Removal of Volatile Organic Compound in the Photothermal Water Purification

In recent years, the photothermal evaporation technology that effectively solves the problem of fresh water shortage has attracted great interest, but the problem is that volatile organic compounds (VOCs) always enter the condensate with vapor during the evaporation process, so the combination of photothermal evaporation and photocatalysis is considered. Herein, narrow‐bandgap β‐MnO 2 is selected as the material for photothermal evaporation and catalysis, and a β‐MnO 2 porous hydrogel (β‐MnO 2 ‐PH) interfacial evaporator with high evaporation efficiency and catalytic degradation of organic pollutants is designed using porous and hydrophilic hydrogels as carriers. The optimized evaporation rate can reach 3.5 kg m −2 h −1 and achieve high light absorption of 93.4% in the full spectral range. This is better than the performance of most MnO 2 ‐based solar evaporator reported so far. In addition, β‐MnO 2 ‐PH has the function of photocatalytic purification and effectively degrades VOCs such as phenol. By combining photothermal action of evaporator with photocatalytic performance, it provides unlimited potential application in solar desalination and industrial wastewater treatment.