Sponge-Supported Reduced Graphene Oxides Enable Synergetic Photothermal and Electrothermal Conversion for Water Purification Coupling Hydrogen Peroxide Production

Abstract

To address the freshwater scarcity issue and the environmental impact of wastewater disposal, herein a novel efficient strategy to enhance the performance of solar-driven interfacial evaporation technique is developed to purify salt-containing wastewater and seawater for sustainable clean water production. This strategy enables photovoltaic electricity to power photothermal conversion for rapidly vaporizing brine using commercial melamine sponge (MS)-supported reduced graphene oxides (MS@rGO). The record-high performance with an evaporation rate of 9.02 kg m−2 h−1 along with a solar-to-vapor efficiency of 287.4% in 7 wt% salt brine is achieved under 1 sun and optimized voltage applied. During evaporating brine, MS@rGO can also efficiently catalyze oxygen reduction for the sustainable production of H2O2 to serve as the broad-acting disinfecting agent in the condensed water. Because applying voltages can facilitate the movement of salt ions in brine, the presented system is endowed with excellent salt-resistance and superior ability of extracting photogenerated electrons, significantly improving the energy utilization efficiency. Therefore, this design provides a new way for highly efficiently applying solar energy in saline wastewater purification and seawater desalination with low cost.