Long-Lasting Hydrogen Evolution and Efficient Dew Harvest Realized via Electrospinning Polyvinylidene Fluoride Membrane on Hybrid Hydrogels

Long-lasting hydrogen evolution and efficient dew harvest is realized via electrospinning a polyvinylidene fluoride (PVDF) membrane on hybrid hydrogels embedded with photocatalytic g-C₃N₄/Pt nanosheets. Due to the hindrance of water evaporation by the hydrophobic PVDF membrane, the drying process of the hybrid hydrogels significantly slows down. Hence, the g-C₃N₄/Pt nanosheets can continue working on photocatalytic splitting of the water molecules in the hydrogels. When the thickness of the PVDF membrane is 48 μm, the hydrogen evolution rate can reach 2,543 μmol h⁻¹ g⁻¹, which is 38% more than that of the hybrid hydrogel without covering. Therefore, the hybrid hydrogels covered with PVDF membrane are able to work with high efficiency for 12 h, sufficient for hydrogen evolution during the daytime. In addition, the hydrophobic PVDF membrane and hydrophilic hydrogels construct a Janus structure and induce a fast transport of water molecules from the hydrophobic to hydrophilic side. It is beneficial for the rapid collection of dew in the morning. Based on the long-lasting hydrogen evolution and efficient dew harvest, the present hybrid hydrogels covered with PVDF membrane are very suitable for the environment rich in solar resource and lack of water supply, such as desert or prairie.