Highly efficient solar evaporator based on Graphene/MoO3-x coated porous nickel for water purification

Solar water evaporation is a promising method for water purification. However, the current photothermal conversion efficiency requires further improvement. Herein, a novel structure (Ni-G-MoO3-x) consisting of graphene (G) and MoO3-x coated porous nickel (Ni) is developed by combining facile chemical vapor deposition (CVD) with hydrothermal methods. The optical absorption and photothermal conversion efficiency of the materials were improved by oxygen vacancies (OVs). The as-prepared solar evaporator exhibits excellent light absorption (96%), good wettability and high conversion efficiency (95%) under 1 sun illumination. In particular, the super hydrophilicity of the evaporator can spontaneously transfer the surface salt back to the bulk seawater in the dark conditions. As a result, a stable evaporation rate can be achieved with the self-driven salt-resistant material in the evaporation cycle of more than three days. Furthermore, the evaporator has an excellent desalination ability and can extract fresh water resources from a variety of water sources (seawater, industrial waste water and organic dye wastewater) through light-to-heat conversion water evaporation technology. This work provides a fundamental guidance and insights on practical applications, thus helping to develop a highly efficient solar evaporator for clean water production.