Molybdenum Carbide/Carbon-Based Chitosan Hydrogel as an Effective Solar Water Evaporation Accelerator

Solar-driven water evaporation is deemed to be a green and sustainable strategy to cope with the global freshwater crisis. However, effective water evaporation to achieve high water yield in practical application is significant but usually neglected. Here, a molybdenum carbide/carbon-based chitosan hydrogel (MoCC-CH) is designed not only as a solar absorber but also as a water evaporation accelerator. The proportion of the chitosan matrix in the hydrogel is tunable to acquire low-tortuosity channels for facilitating solar-driven evaporation. Thus, the evaporation rate of MoCC-CH is up to ∼2.19 kg m–2 h–1, and a corresponding solar-thermal conversion efficiency of 96.15% is obtained under one sun illumination. The highly efficient water generation is also attributed to a novel water collection device and valid cooling strategy. The outdoor experiment possesses an excellent daily freshwater yield of 13.86 kg m–2 in one sunny day. The successful demonstration of both the well-designed hybrid hydrogel and an optimized passive solar desalination system offers the possibility for sustainable solar-driven desalination.