Nanofibrillation of a Bleached Acacia Pulp by Grinding with Carboxymethylation Pretreatment

In this study,carboxymethylation,which introduces carboxyl groups to hydroxyl sites in pulp fibers,was used as a pretreatment before mechanical nanofibrillation.The carboxyl group content of the pulp fibers was greatly affected by the dosage of chloroacetic acid and the reaction temperature.During the following fibrillation process,it was found that pulp fibers with higher carboxyl group content exhibited higher water holding capacities and smaller dimensions.A more homogenous structure with a higher amount of individual fibrils was also observed in FE-SEM images of pulp fibers with high carboxyl group content.This can be explained by a high ionic group content in the fiber wall resulting in lower delamination resistance,making the fibrils easier to separate.Carboxymethylation pretreatment as a facilitator of fibrillation in cellulosic pulps is an efficient way to obtain cellulose nanofibrils and consequently decrease the energy consumption of the process.

Cellulose-based Antimicrobial Composites and Applications: A Brief Review

Cellulose-based antimicrobial composites,typically in the form of functional films and cloth,have received much attention in various applications,such as food,medical and textile industries.Cellulose is a natural polymer,and is highly biodegradable,green,and sustainable.Imparting antimicrobial properties to cellulose,will significantly enhance its applications so that its commercial value can be boosted.In this review paper,the use of cellulose for antimicrobial composites’preparation was discussed.Two different approaches:surface loading/coating and interior embedding,were focused.Three most widely-applied sectors:food,medical and textile industries,were highlighted.Nanocellulose,as a leading-edge cellulose material,its unique application on the antimicrobial composites,was particularly discussed.

Shedding light on the reversible deactivation of carbon-supported single-atom catalysts in hydrogenation reaction

Carbon-supported single-atom catalysts were found to suffer reversible deactivation in catalytic hydrogenation,but the mechanism is still unclear.Herein,nitro compounds hydrogenation catalyzed by N-doped carbon-supported Co single atom(Co1/NC)was taken as a model to uncover the mechanism of the reversible deactivation phenomenon.Co1/NC exhibited moderate adsorption towards the substrate molecules(i.e.,nitro compounds or related intermediates),which could be strengthened by the confinement effect from the porous structure.Consequently,substrate molecules tend to accumulate within the pore channel,especially micropores that host Co1,making it difficult for the reactants to access the active sites and finally leading to their deactivation.The situation could be even worse when the substrate molecules possess a large size.Nevertheless,the catalytic activity of Co1/NC could be restored via a simple thermal treatment,which could remove the adsorbates within the pore channel,hence releasing active sites that were originally inaccessible to reactants.

Eutectic-derived high-entropy nanoporous nanowires for efficient and stable water-to-hydrogen conversion

Combining multiple metal elements into one nanostructure merits untold application potential but is still a challenge for the traditional bottom-up synthesis method.Herein,we propose a eutectic-directed self-templating strategy to prepare two multicomponent nanostructured alloys(PtPdRhIrNi(D-SN)and NiPtPdRhIrAl(D-SS))through the combination of rapid solidification with dealloying.The PtPdRhIrNi nanoporous nanowires(NPNWs)represent a new family of high-entropy alloys(HEAs)containing delicate hierarchical nanostructure with ultrafine ligament sizes of~2 nm in addition to one-dimensional(1D)morphology.Moreover,the PtPdRhIrNi NPNWs display excellent electrocatalytic activity and stability toward hydrogen evolution reaction,with the low overpotential of 22 and 55 mV to afford a current density of 10 mA·cm^(−2)in 0.5 M H_(2)SO_(4)and 1.0 M KOH electrolytes,respectively.The enhanced electrocatalytic performance can be attributed to the high-entropy effect favoring the surface electronic structure for the optimized activity,the promotion impact of Ni,1D morphology facilitating the electron transport,and the nanoporous structure promoting the electrolyte diffusion.