Laser thermal synthesis of reduced graphene oxide/CuS nanocomposites for efficient solar-driven water purification

Utilizing inexhaustible solar energy to realize water purification is a green and sustainable solution to water pollution. Herein, a laser thermal method was adopted to prepare reduced graphene oxide/CuS nanocomposites (rGO/CuS) for solar-driven water purification. By laser treatment of aqueous NaOH solution containing graphene oxide, CuCl2, and thiourea, rGO was formed, and CuS was anchored on the rGO surface at an elevated temperature. The prepared rGO/CuS showed high photothermal conversion ability, and the water evaporation enthalpy was reduced for rGO/CuS loaded melamine sponge (rGO/CuS-MS). A notable high solar-driven water evaporation rate of 2.09 kg•m−2•h−1 was achieved for rGO/CuS-MS under 1.0 kW•m−2 solar irradiation. Integrating with the adsorption ability, the rGO/CuS-MS demonstrated efficient removal capacity of rhodamine B (RhB), volatile m-dinitrobenzene (m-NB), and Ni2+ in water under solar irradiation. The results indicated that the water evaporation could enhance the RhB, m-NB, and Ni2+ adsorption capacity of rGO/CuS-MS. Both the unevaporated and distilled water can be efficiently purified by rGO/CuS-MS under solar irradiation. Also, increasing solar flux showed contribution to higher RhB removal ratio for the accelerated water evaporation. This study could contribute to preparing rGO-based nanocomposites for water resources remediation applications.