News Network News Recently, Qingdao University National International Joint Research Center for Hybrid Materials Technology (national-level "One Center and Two Bases") / Hybrid Materials Research Institute published the cover research paper titled "Bioinspired Graphene Oxide Membranes with pH-Responsive Nanochannels for High-Performance Nanofiltration" in the top international journal "ACS Nano" (the journal is a TOP journal in Division 1 of the Chinese Academy of Sciences and belongs to Nature Index journal, with an impact factor of 15.881), which reports the center's original work in the field of carbon-based hybrid nanofiltration membranes using nano-confined space to control mass transfer. The first author of this research work is Zhang Zhijie, a master student from the College of Materials Science and Engineering (instructor: Huang Linjun), and the corresponding authors are Professor Huang Linjun and Tang Jianguo from Qingdao University and Professor Jun Chen from UCLA. Qingdao University is the first communication unit.

In the field of membrane separation, how to balance the selectivity and permeability of membranes is an international problem in this field. This research work realizes the controllable adjustment of the interlayer spacing and surface charge of graphene oxide sheets by regulating the size and conformational changes of the cross-linked molecules, so as to achieve the purpose of precisely designing the internal confinement mass transfer nanochannels, which is expected to break the trade-off effect of ionic selectivity and permeability of membrane technology to obtain high-performance nanofiltration membranes. In this study, a graphene oxide hybrid nanofiltration membrane with synergistic effects of size and charge was constructed, and then its water permeation and separation properties were tested, and the gating performance of the graphene oxide hybrid nanofiltration membrane under pH response characteristics was studied. Finally, a rational explanation for the transport mechanism of intramembrane nanochannels is proposed based on the experiments. In addition, it enables the graphene oxide hybrid membrane to have a reversible gating law through the synergistic effect of regulating nanochannel size and electrostatic interaction, and the enhanced permeability and molecular separation performance show its potential application value in the field of high-performance nanofiltration. At the same time, this achievement provides insights into the design and construction of graphene oxide hybrid nanofiltration membranes with controllable pH-responsive gating properties, indicating a great progress in nanofiltration membranes in a wide range of applications. The main innovations of the paper are as follows: (1) By designing different composition ratios of GO and GO-PEI to control the nanochannel size and surface charge of graphene oxide hybrid films, based on the synergy of size sieving and charge selection double effects A graphene oxide hybrid nanofiltration membrane with fast water permeation and high separation performance was prepared; (2) The pH-response gating performance of the graphene oxide hybrid nanofiltration membrane was demonstrated through tests, and the effect mechanism of the changes of the size and surface charge of the nanochannels in the membrane with pH on the mass transfer behavior was verified by experiments.

Paper link: https://doi.org/10.1021/acsnano.1c02719