Quasimetallic Molybdenum Carbide–Based Flexible Polyvinyl Alcohol Hydrogels for Enhancing Solar Water Evaporation

Abstract

AbstractSolar interfacial water evaporation has been regarded as a promising technique for large‐scale water purification by utilizing sustainable solar energy. However, fresh water production, especially in resource limited areas, still remains challenging and needs to be addressed. Here, molybdenum carbide (MoCx)– based polyvinyl alcohol hydrogels (MoCxPH) are strategically designed as flexible and highly efficient solar evaporators for producing clean water from different water‐bearing media. Through adjusting the calcination temperatures, the phase transition of MoCx from η‐MoC to β‐Mo2C makes the product to be a quasimetal from a semiconductor, leading to a strong broadband adsorption over the full solar spectrum together with excellent photothermal conversion capability. The hydrogel‐based solar evaporator exhibits an average water evaporation rate of 1.59 kg m−2 h−1 with superb solar thermal efficiency up to 83.6% under one sun illumination. This scalable solar evaporator can be used to generate clean water from contaminated water with rejections close to 100% for organic dyes and metal ions. The solar water evaporator has potential applications for the remote areas to deal with the drinkable water shortage problem.