In-Situ Self-Assembled ZnO Foam Based on Graphene-Like Ultrathin Nanosheets

It is still a challenge to prepare 2D ultrathin ZnO in a simple method, especially for the in-situ growth of 2D ultrathin ZnO on different substrates. Herein the ZnO foam with high specific surface area is successfully assembled in situ from graphene-like ultrathin nanosheet on various substrates, including rigid fluoride doped tin oxide, Ni foam, and flexible indium tin oxide, carbon cloth, etc. The thickness of graphene-like nanosheet is just ≈1.5 nm. The results reveal that the specific surface area of ZnO nanosheets is 90.7 m² g⁻¹. The high specific surface area of the hydrophilic ZnO foam and its in-situ growth characteristic make it promising water channel in solar-driven interfacial water evaporation system. By using a flexible carbon cloth/ZnO foam (C-ZnO) Janus absorber, a high rate of water evaporation (2.4 kg m⁻² h⁻¹), which is 4.6 times higher than that of natural evaporation is demonstrated. This work provides a new method in the design of ZnO ultrathin nanosheets, what's more, the facile growth of the ZnO foam on various substrates make it possible for the application in optoelectronic devices.