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Bacterial cellulose (BC) nanofiber-supported polyaniline (PANI) nanocomposites have been synthesized via in situ polymerization of aniline onto BC nanofibers scalfold. Optimized preparation conditions were employed to achieve higher conductivity. The resultant BC/PANI nanocomposites were fully characterized in terms of structure, morphology, and thermal stability. The flake-like morphology of BC/PANI nanocomposites was observed using a field-emission gun scanning electron microscope. By manipulating the ordered flake-type nanostructure, BC/PANI nanocomposites achieved outstanding electrical conductivity as high as 5.1 S/cm. The as-prepared BC/PANI nanocomposites demonstrated a mass-specific capacitance of 273 F/g at 0.2 A.g −1 current density in supercapacitor application, the highest value reported so far for polymer-supported PANI composites.

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Single atom catalysts (SACs) are widely researched in various chemical transformations due to the high atomic utilization and catalytic activity. Carbon‐supported SACs are the largest class because of the many excellent properties of carbon derivatives. The single metal atoms are usually immobilized by doped N atoms and in some cases by C geometrical defects on carbon materials. To explore the catalytic mechanisms and improve the catalytic performance, many efforts have been devoted to modulating the electronic structure of metal single atomic sites. Doping with polynary metals and heteroatoms has been recently proposed to be a simple and effective strategy, derived from the modulating mechanisms of metal alloy structure for metal catalysts and from the donating/withdrawing heteroatom doping for carbon supports, respectively. Polynary metals SACs involve two types of metal with atomical dispersion. The bimetal atom pairs act as dual catalytic sites leading to higher catalytic activity and selectivity. Polynary heteroatoms generally have two types of heteroatoms in which N always couples with another heteroatom, including B, S, P, etc. In this Review, the recent progress of polynary metals and heteroatoms SACs is summarized. Finally, the barriers to tune the activity/selectivity of SACs are discussed and further perspectives presented.

Bacterial cellulose (BC) nanofibers were biosynthesized by Acetobacter xylinum NUST5.2, and displayed a remarkable capability for orienting TiO(2) nanoparticle arrays. Large quantities of uniform BC nanofibers coated with TiO(2) nanoparticles can be easily prepared by surface hydrolysis with molecular precision, resulting in the formation of uniform and well-defined hybrid nanofiber structures. The mechanism of arraying spherical TiO(2) nanoparticles on BC nanofibers and forming well-defined, narrow mesopores are discussed in this paper. The BC/TiO(2) hybrid nanofibers were used as photocatalyst for methyl orange degradation under UV irradiation, and they showed higher efficiency than that of the commercial photocatalyst P25.

As CO 2 emissions are sharply increasing, processes for converting CO 2 into value-added products are becoming more desirable. Ruthenium-based catalysts are the most active for CO 2 methanation; however, their substantially higher cost relative to transition metals makes them prohibitive for industrial application. In this study, we demonstrate porous hexagonal boron nitride (pBN) supports (an ideal support material for thermocatalysts due to the high thermal stability and conductivity) to improve the utilization of Ru and simultaneously enhance the catalytic activity and selectivity for CO 2 methanation. A simple vacuum filtration process is proposed that allows the Ru precursor to quickly locate the defects of pBN, where atomic Ru can be restricted onto the defects via B, N coordination through an annealing treatment. The B and N coordinations reduce the valence state of atomic Ru. The as-prepared catalyst with low Ru loading (0.58 wt %) exhibits CH 4 selectivity up to 93.5%, catalytic stability after 110 h, and a higher reaction rate [1.86 mmol CO 2 /(g cat s)] at 350 °C and 1.0 MPa compared to other nanoparticle catalysts. Both atomic-scale size and low valence state of atomic Ru supported on pBN are responsible for the improvement of CH 4 production rate as confirmed by density functional theory simulation.

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