MoS2 Nanosheet–Carbon Foam Composites for Solar Steam Generation

With the fast development of modern society and the sharp increase in population, water pollution and shortage of freshwater resources have become increasingly severe problems for mankind. Steam generation by solar energy is an important method for desalination and sewage purification. MoS2 is a two-dimensional graphene-like material, which has gained wide attraction due to its excellent light absorption and optoelectronic properties. Herein, a low-temperature carbonization method is used to prepare bio-carbon foam, followed by hydrothermal deposition of MoS2 nanosheets to prepare MoS2/bio-carbon foam composites (MBCF) for the first time, which are utilized to fabricate a solar steam generator. The MBCF can achieve about 96% solar absorption and a water evaporation rate of 1.49 kg·m–2·h–1 under 1000 W·m–2 simulated solar irradiation. After subtracting the corresponding evaporation rate of 0.085 kg·m–2·h–1 under a dark field, its net evaporation rate reaches 1.41 kg·m–2·h–1. The effects of hydrothermal time and foam thickness on water evaporation performance are also investigated. The optimum efficiency is obtained when the hydrothermal time is 20 h and the bio-carbon foam thickness is 10 mm. The device exhibits stable evaporation efficiency whether in pure water or seawater under long-time solar illumination (3 h) for 10 cycles. However, the heat loss calculation indicates that only 79.2% of the solar energy is used for water evaporation, lower than 88.3% calculated using the standard latent heat of water vaporization of 2260 kJ·kg–1. The reasons are discussed in the article.