Constructing a high concentration CuO/CeO_(2) interface for complete oxidation of toluene:The fantastic application of spatial confinement strategy

In this paper,CeO_(2) substrate was prepared by the sol-gel method,further CuO was introduced by adding the copper complexes with chelating agents into the sol-gel precursors of CeO_(2),in which different chelating agents(β-cyclodextrin,glucose and trimesic acid)were tried.This synthesis method helps the CuO species to disperse very uniformly in the CeO_(2) substrates.When the amount of copper oxide is up to33 mol%,the CuO/CeO_(2) samples can still maintain a highly dispersed state.The CeO_(2) and CuO/CeO_(2)samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),temperature-programmed reduction of hydrogen(H_(2)-TPR),temperature-programed desorption(O_(2)-TPD),etc.It is found that the CuO/CeO_(2) catalyst prepared byβ-cyclodextrin(βCuO/CeO_(2)) exhibits better catalytic performance owing to the higher dispersion,higher specific surface area,more defects,more active Ce3+and Cu^(+) ions,more oxygen vacancies,more surface active oxygen,relatively better low temperature reducibility,and the exposed(110) active facets.In the condition of 1000×10-6toluene in air and WHSV=60000 mL/(g·h),the T90for toluene conversion is 227℃.The reaction mechanism of toluene catalytic oxidation over CeO_(2)andβCuO/CeO_(2) is discussed by the study of in-situ DRIFTS.This work affords a simple and efficient method for the synthesis of highly dispersed bimetal oxide catalysts with high contents.

Oxygen self-doping pyrolyzed polyacrylic acid as sulfur host with physical/chemical adsorption dual function for lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries with high theoretical capacity and energy density need to solve problems such as the high decomposition energy barrier of Li_(2)S and large volume change of sulfur in the charging process caused by the shuttle effect before practical application.Herein,a green synthesis method is used to prepare polyacrylic acid(PAA)superabsorbent material,and then the pyrolyzed PAA(P/PAA)material is obtained as the positive electrode of Li-S battery.Density functional calculation reveals that the oxygen self-doping pyrolyzed polyacrylic acid(P/PAA)delivered stronger binding energy toward Li2S species in carbonyl C=O than that of graphite powder(GP)which are-1.58 eV and-1.02 eV,respectively.Coupled with the distribution of relaxation time analysis and the in-situ electrochemical impedance approach,it is further demonstrated that the designed P/PAA as sulfur host plays a physical/chemical adsorption dual function in maintaining the stability and rate performance of batteries.With an initial discharge capacity of 1258 mAh/g at 0.1 C and a minimal capacity decline of 0.05%per cycle even after 800 cycles at 0.5 C,the produced cathode demonstrated outstanding electrochemical performance.The average Coulombic efficiency is nearly 100%.The P/PAA electrodes may typically retain 96%of their capacity while declining on average only 0.033%per cycle after 130 cycles at 3 C.This effort provides a new method for the future development of heteroatomic self-doping superabsorbent with promising adsorption properties for polysulfides as cathode materials of Li-S batteries.

Tea-derived carbon materials as anode for high-performance sodium ion batteries

Sodium-ion batteries(SIB) have attracted widespread attention in large-scale energy storage fields owing to the abundant reserve in the earth and similar properties of sodium to lithium. Biomass-based carbon materials with low-cost, controllable structure, simple processing technology, and environmental friendliness tick almost all the right boxes as one of the promising anode materials for SIB. Herein, we present a simple novel strategy involving tea tomenta biomass-derived carbon anode with enhanced interlayer carbon distance(0.44 nm) and high performance, which is constructed by N,P co-doped hard carbon(Tea-1100-NP) derived from tea tomenta. The prepared Tea-1100-NP composite could deliver a high reversible capacity(326.1 m Ah/g at 28 m A/g), high initial coulombic efficiency(ICE = 90% at 28 m A/g),stable cycle life(262.4 m Ah/g at 280 m A/g for 100 cycles), and superior rate performance(224.5 m Ah/g at 1400 m A/g). Experimental results show that the excellent electrochemical performance of Tea-1100-NP due to the high number of active N,P-containing groups, and disordered amorphous structures provide ample active sites and increase the conductivity, meanwhile, large amounts of microporous shorten the Na+diffusion distance as well as quicken ion transport. This work provides a new type of N,P co-doped high-performance tomenta-derived carbon, which may also greatly promote the commercial application of SIB.