Engineering self-floating Fe2O3/N,O-doped carbon foam as a bifunctional interfacial solar evaporator for synergetic freshwater production and advanced oxidation process

Interfacial solar-driven water evaporation is an appealing technology to mitigate freshwater crisis mainly caused by increasingly aggravated water pollution. Unfortunately, when polluted water is used, toxic organic pollutants might remain or even get enriched, leading to more serious water pollution. Herein, a self-floating bifunctional Fe2O3/N,O-doped carbon foam (FCF) evaporator is easily prepared by carbonization of waste polyester for simultaneous interfacial solar-driven water production and photocatalytic degradation of organic pollutants. The as-prepared FCF possesses low heat conductivity (0.074 W m-1 K-1), 3D interconnected pores, abundant functional groups as well as super-hydrophilicity, which impart FCF with fast water transport, high light ab-sorptivity (98%), good photothermal conversion, and low vaporization enthalpy. Therefore, FCF presents high evaporation performance, e.g., 2.50 kg m- 2 h-1 under 1 Sun irradiation, outperforming many advanced solar evaporators. Furthermore, the synergistic effect of heteroatom-doped carbon foam, Fe2O3 nanoparticle, and interfacial thermal energy is certified on the activation of peroxymonosulfate (PMS) to form diverse reactive oxide species (e.g., SO4 center dot-), which promote the degradation of diverse organic dyes or mixed dyes. Compared with FCF and PMS systems, the rate constant of FCF + PMS system (3.79 x10- 2 min-1) is enhanced by 173.8 and 1.6 times, respectively. In outdoor experiments, the amount of freshwater production from per meter square (13 kg) satisfies with 5 adults' daily water demand, and the dye degradation efficiency reaches 99.8%. The integration of advanced oxidation process into interfacial solar evaporation offers a promising strategy to simultaneously solve freshwater scarcity and sewage disposal.

Automated summary

This study presents a self-floating bifunctional evaporator for interfacial solar-driven water production and photocatalytic degradation of organic pollutants. The evaporator demonstrates fast water transport, high light absorption, and excellent evaporation performance, producing 13 kg of freshwater per square meter and achieving 99.8% dye degradation efficiency.