Double spatial confinement on ruthenium nanoparticles inside carbon frameworks as durable catalysts for a quasi-solid-state Li–O_(2) battery

The rational design of large-area exposure,nonagglomeration,and longrange dispersion of metal nanoparticles(NPs)in the catalysts is critical for the development of energy storage and conversion systems.Little attention has been focused on modulating and developing catalyst interface contact engineering between a carbon substrate and dispersed metal.Here,a highly dispersed ultrafine ruthenium(Ru)NP strategy by double spatial confinement is proposed,that is,incorporating directed growth of metal–organic framework crystals into a bacterial cellulose templating substrate to integrate their respective merits as an excellent electrocatalytic cathode catalyst for a quasi-solid-state Li–O_(2) battery.The porous carbon matrix with highly dispersed ultrafine Ru NPs is well designed and used as cathode catalysts in a Li–O_(2) battery,demonstrating a high discharge areal capacity of 6.82 mAh cm^(–2) at 0.02 mA cm^(–2),a high-rate capability of 4.93 mAh cm^(–2) at 0.2 mA cm^(–2),and stable discharge/charge cycling for up to 500 cycles(2000 h)with low overpotentials of~1.4 V.This fundamental understanding of the structure–performance relationship demonstrates a new and promising approach to optimize highly efficient cathode catalysts for solid-state Li–O_(2) batteries.

Recent progress of covalent organic frameworks membranes:Design,synthesis,and application in water treatment

To date,significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials.Covalent organic frameworks(COFs),an important branch of the porous crystalline family,possess the peculiarity of ultrahigh surface area,adjustable pore size,and facile functionality.Exciting studies from design fabrication to potential applications in water treatment by COF-based membranes(COMs)have emerged.This review summarizes various preparation strategies and synthesis mechanisms for COMs,including layer-by-layer stacking,in situ growth,interfacial polymerization,and electrochemical synthesis,and briefly describes the advanced characterization techniques for COMs.Moreover,the application of COMs in heavy metal removal,dye separation,purification of radionuclides,pollutant detection,sea water desalination,and so on,is described and discussed.Finally,the perspectives on future opportunities for designing COMs in water purification have been proposed.

Biochar-based materials in environmental pollutant elimination,H_(2) production and CO_(2) capture applications

Biochar and biochar-based materials have been studied extensively in multidisciplinary areas because of their outstanding physicochemical properties.In this review article,biochar and biochar-based materials in the removal of environmental pollutants,hydrogen generation and carbon dioxide capture were summarized and compared.The interaction mechanisms were discussed from the experimental results and characterization analysis.The high porous structures,active surface sites,(co)doping of single metals/nonmetals,and incorporation of metal oxides or other materials improved the high activity of biochar-based materials in their applications.However,there are still some challenges such as:(1)the fact that H_(2) generation with high selectivity or the produced syngas to meet the real application requirement in industrial is the main challenge in H_(2) production;(2)the fact that the selective capture of CO_(2) with high stability,high adsorption capacity and recyclability at low-cost should be considered and focused on;(3)the sorption-(photo)degradation of the organic chemicals;and(4)the fact that the sorption-reduction-extraction/solidification of metals/radionuclides are efficient methods for the elimination of environmental pollutants.In the end,the perspectives,challenges and possible techniques for biochar-based materials’real application in future were described.