Synergistic photocatalytic-photothermal contribution enhanced by recovered Ag+ ions on MXene membrane for organic pollutant removal

The coordinated removal of pollutants in wastewater, especially metal ions and organic pollutants, is regarded as a tough challenge and has focused wide attentions. Synergistic photocatalytic-photothermal route is a powerful technology for the potential wastewater treatment. Herein, we designed a synergistic photocatalytic-photothermal system based on two-dimensional Ti3C2Tx MXene (TCM) membrane for simultaneous recovery of Ag+ ions and removal of aqueous rhodamine B (RhB). The photo-reduction of Ag+ ions into Ag nanoparticles with the conversion rate up to 100% was achieved on TCM membrane under visible-light irradiation. These Ag nanoparticles uniformly deposited on the surface and interlayers of TCM membrane. It facilitated the separation of photo-generated charges for forming more active species, including both ∙O2- and ∙OH radicals, to oxide RhB molecular. At the same time, the surface plasma effect of Ag nanoparticles enhanced the light adsorption and photothermal conversion efficiency (∼81%) on the TCM membrane. Conversely, photothermal effect was beneficial for further enhancing the reaction rate of both reduction of Ag+ ions and photo-oxidation of RhB by concentrating the solution and promoting the electron transfer. The novelty of the synergistic photocatalytic-photothermal contribution is significant for simultaneous recovery of metal ions and removal of organic pollutants in wastewater.