Structurally optimized MXene-based photocatalytic membrane to achieve self-cleaning properties and enhanced removal for small molecule from wastewater

[Display omitted] •A novel O-g-C3N4@MXene/PES composite membrane was constructed by vacuum filtration.•The membrane achieved a high removal ratio for small molecule from wastewater.•The composite membrane exhibited excellent anti-fouling and self-cleaning ability.•DFT calculation revealed the mechanism for improving photocatalytic activity. Membrane contamination not only reduces the efficacy of separation; but also increases the cost due to frequent application of cleaning agents and shortens membrane life. Therefore, we had constructed a new membrane that could be effectively used to solve the pollution problem. In this work, MXene nanosheets with ultra-thin lamellae have been fabricated by chemical etching, followed by the inclusion of oxygen-doped graphite-phase carbon nitride (OCN) photocatalyst with porous structure. The vacuum-assisted device was utilized to synthesize MXene@OCN/Polyethersulfone (MX-OCN) photocatalytic composite membrane possessing self-cleaning ability. The thickness, average surface roughness and the embedding structure of the MX-OCN composite membranes were found to change significantly, leading to the permeability of the MX-OCN membrane up to 1313 L·m−2·h−1·bar−1. The interlayer sieving and photocatalysis provided the MX-OCN membrane a high removal ratio for the contaminants like: Congo red: 98 %, Trolybenzene blue: 96 %, Tetracycline hydrochloride: 83 %. During self-cleaning the composite membrane maintained a removal ratio of 94 % and high for CR after 4 cycles, thus effectively alleviating the problem of membrane pollution. Density function theory calculation (DFT) showed that O atom doping could enhance the charge density and reduce the band gap width, which would be more favorable to the photocatalytic activity.