Reassessing the Role of Thermal Convection in Simultaneous Water Production and Pollutant Degradation in Interfacial Photothermal-Photocatalytic Systems.

Abstract

The interfacial photothermal-photocatalytic systems can generate clean water while purifying wastewater containing organic pollutants, but the impact of thermal convection on synergistic effects remains unexplored. This paper aims to regulate the thermal convection at the interface to significantly enhance the synergistic effect of interfacial photothermal-photocatalytic systems. A novel heterogeneous structure comprising iron-based metal-organic frameworks and multi-walled carbon nanotubes with a gelatin-polyvinyl alcohol (PVA) double network hydrogel (MWCNTs@NM88B/PVA/gelatin hydrogel, denoted as MMH) is developed and employed in the construction of the solar-driven interfacial evaporation (SIE) system. The system shows high activity for solar water evaporation and simultaneous photocatalytic degradation of organic pollutants. MMH demonstrates an evaporation rate of 2.84 kg m^-2 h^-1, achieving an efficiency of 95.3% under 1 sun. COMSOL simulations reveal that the implementation of a three-phase interface configuration with SIE technology significantly boosts thermal convection, effectively diminishing the barrier to gas release from the reaction system and consequently enhancing the efficiency of the interfacial photothermal-photocatalytic process. Furthermore, the potential mechanism of photocatalytic decomposition of organic pollutants in MMH/H₂O₂/visible light reaction system is proposed by combining the experiments of KPFM, in situ XPS, and ESR spectra. Therefore, this work offers a fresh perspective on evaluating the impact of thermal convection on water evaporation and pollutant degradation in interface photothermal-photocatalytic systems.