2D Heterostructure Membranes with Sunlight-Driven Self-Cleaning Ability for Highly Efficient Oil–Water Separation

Introducing solar energy into membrane filtration to decrease energy and chemicals consumption represents a promising direction in membrane fields. In this study, a kind of 0D/2D heterojunction is fabricated by depositing biomineralized titanium dioxide (TiO₂) nanoparticles with delaminated graphitic carbon nitride (g-C₃N₄) nanosheets, and subsequently a kind of 2D heterostructure membrane is fabricated via intercalating g-C₃N₄@TiO₂ heterojunctions into adjacent graphene oxide (GO) nanosheets by a vacuum-assisted self-assembly process. Due to the enlarged interlayer spacing of GO nanosheets, the initial permeation flux of GO/g-C₃N₄@TiO₂ membrane reaches to 4536 Lm⁻² h⁻¹ bar⁻¹, which is more than 40-fold of GO membranes (101 Lm⁻² h⁻¹ bar⁻¹) when utilized for oil/water separation. To solve the sharp permeation flux decline, arising from the adsorption of oil droplets, the a sunlight-driven self-cleaning process is followed, maintaining a flux recovery ratio of more than 95% after ten cycles of filtration experiment. The high permeation flux and excellent sunlight-driven flux recovery of these heterostructure membranes manifest their attractive potential application in water purification.