No abstract

Cellulose nanofibers were prepared using TEMPO/NaBr/NaClO oxidation of kraft pulp and successive ultrasonic treatment, and the properties were characterized by conductimetric titration, X‐ray diffraction, and atomic force microscopy. The resulting product was then applied as an anionic microparticle to constitute a microparticulate system with cationic polyacrylamide (CPAM), to induce the flocculation of the kaolin clay suspension. The flocculation effect was evaluated by determining the relative turbidity of clay suspension. The results showed that the obtained cellulose nanofibers had cellulose I structure with higher crystallinity than that of the kraft pulp, and their cross‐sectional dimension was in the range of 3–5 nm. They had more negative zeta potential at neutral and alkaline conditions. It was found that the microparticulate system showed high flocculation effect on kaolin clay at a very low level of nanofiber addition, and a high shear level after CPAM addition was helpful for the flocculation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40450.

With use of the first-principles density functional theory with the inclusion of the on-site Coulomb interaction of the Ce4f electrons (DFT+U) method, the adsorption of CO on the (110) surface of a stoichiometric Ce0.75Zr0.25O2 system is studied systematically. It is found that, (1) in addition to the carbonate-like CO3 structures, there exists a new adsorption species (a bent CO2 − structure) on the Ce0.75Zr0.25O2(110) surface, and (2) the Zr-dopant can enhance the adsorption of CO and improve the CO oxidation process on the ceria surface by promoting the desorption of CO2.

No abstract

Layered MXene films have shown enormous potential for wide applications due to their high electrical conductivity and unique laminated microstructure. However, the intrinsic susceptibility to oxidation and the mechanical fragility of MXene films are the two major bottlenecks that prevent their widespread industrial applications. Here, a facile yet efficient assembly strategy is proposed to address these issues by increasing the alignment and compactness of MXene layers as well as strengthening the interlayer interactions. This method involves the gelation of MXene flakes with a multifunctional inorganic “mortar” polymer (ammonium polyphosphate, APP) followed by quasi‐solid‐state assembly enabled by a mechanical rolling process, by which the 3D gel network is transformed into 2D freestanding MXene films with unprecedented flake alignment and compactness. Besides, due to the multiple molecular‐level interactions (hydrogen bonding, coordination bonding, and electrostatic force) between APP and MXene flakes, the resultant MXene‐APP film (MAF) displays high mechanical strength (286.4 ± 20.3 MPa) and excellent electrical conductivity (8012.4 ± 325.6 S cm−1), along with remarkable environmental stability. As an application demonstration, MAF exhibits outstanding electromagnetic interference shielding effectiveness with long‐term durability, highlighting the great potential of this gelation‐assisted assembly strategy in fabricating large‐area, high‐performance MXene films for diverse real‐world applications.