In situ XRD and electrochemical investigation on a new intercalation-type anode for high-rate lithium ion capacitor

A new intercalation-type anode material is reported herein to improve the lithium storage kinetics for high-rate lithium ion capacitors.The crystal structure of orthorhombic NaNbO3 indicates two possible tunnels for lithium ions insertion into NaNbO3 host along the<101>and<141>directions.Moreover,in situ XRD is conducted to investigate the lithium storage mechanism and structural evolution of the NaNb O_(3) anode,demonstrating its intercalation behavior through(101)and(141)planes.Furthermore,the rGO nanosheets are introduced to facilitate the charge transfer,which also effectively prevent the aggregation of NaNbO3 nanocubes.As expected,the NaNbO_(3)/rGO nanocomposites possess remarkable reversible capacity(465 mA h g^(-1) at 0.1 A g^(-1)),superior rate capability(325 mA h g^(-1) at 1.0 A g^(-1))and cycling stability,attributed to their synergistic effect and high Li+diffusion coefficient DLi[D(NaNbO_(3)/rGO)/D(NaNbO_(3))≈31.54].Remarkably,the NaNbO3/rGO-based LIC delivers a high energy density of 166.7 W h kg^(-1) at 112.4 W kg^(-1) and remains 24.1 W h kg^(-1) at an ultrahigh power density of26621.2 W kg^(-1),with an outstanding cycling durability(90%retention over 3000 cycles at 1.0 A g^(-1)).This study provides new insights on novel intercalation-type anode material to enrich the materials system of LICs.

Bioregeneration of spent activated carbon:Review of key factors and recent mathematical models of kinetics

The disposal of spent activated carbon(AC) will inevitably create secondary pollution. In overcoming this problem, the spent AC can be regenerated by means of biological approach. Bioregeneration is the phenomenon in which through the action of microorganisms, the adsorbed pollutants on the surface of the AC will be biodegraded and this enables further adsorption of pollutants to occur with time elapse. This review provides the challenges and perspectives for effective bioregeneration to occur in biological activated carbon(BAC)column. Owing to very few reported works on the bioregeneration rate in BAC column, emphasis is put forward on the recently developed models of bioregeneration kinetic in batch system. All in all, providing potential solutions in increasing the lifespan of AC and the enhancement of bioregeneration rate will definitely overcome the bottlenecks in spent AC bioregeneration.

Insights into the efficient charge separation over Nb_(2)O_(5)/2D-C_(3)N_(4) heterostructure for exceptional visible-light driven H_(2) evolution

Two-dimensional carbon nitride(2 D-C_(3) N_(4))nanosheets are promising materials in photocatalytic water splitting,but still suffer from easy agglomeration and fast photogene rated electron-hole pairs recombination.To tackle this issue,herein,a hierarchical Nb_(2) O_(5)/2 D-C_(3) N_(4) heterostructure is precisely constructed and the built-in electric field between Nb_(2)O_(5) and 2 D-C_(3) N_(4) can provide the driving force to separate/transfer the charge carriers efficiently.Moreover,the strongly Lewis acidic Nb_(2)O_(5) can adsorb TEOA molecules on its surface at locally high concentrations to facilitate the oxidation reaction kinetics under irradiation,resulting in efficient photogene rated electrons-holes separation and exceptional photocatalytic hydrogen evolution.As expected,the champion Nb_(2)O_(5)/2 D-C_(3)N_(4) heterostructure achieves an exceptional H2 evolution rate of 31.6 mmol g^(-1) h^(-1),which is 213.6 times and 4.3 times higher than that of pristine Nb_(2)O_(5) and2 D-C_(3)N_(4),respectively.Moreover,the champion heterostructure possesses a high apparent quantum efficiency(AQE)of 45.08%atλ=405 nm and superior cycling stability.Furthermore,a possible photocatalytic mechanism of the energy band alignment at the hetero-interface is proposed based on the systematical characterizations accompanied by density functional theory(DFT)calculations.This work paves the way for the precise construction of a high-quality heterostructured photocatalyst with efficient charge separation to boost hydrogen production.

Determination of the archaeal and bacterial communities in two-phase and single-stage anaerobic systems by 454 pyrosequencing

2-Phase anaerobic digestion（AD）, where the acidogenic phase was operated at 2 day hydraulic retention time（HRT） and the methanogenic phase at 10 days HRT, had been evaluated to determine if it could provide higher organic reduction and methane production than the conventional single-stage AD（also operated at 12 days HRT）. 454 pyrosequencing was performed to determine and compare the microbial communities. The acidogenic reactor of the 2-phase system yielded a unique bacterial community of the lowest richness and diversity, while bacterial profiles of the methanogenic reactor closely followed the single-stage reactor. All reactors were predominated by hydrogenotrophic methanogens, mainly Methanolinea. Unusually, the acidogenic reactor contributed up to 24%of total methane production in the 2-phase system. This could be explained by the presence of Methanosarcina and Methanobrevibacter, and their activities could also help regulate reactor alkalinity during high loading conditions through carbon dioxide production. The enrichment of hydrolytic and acidogenic Porphyromonadaceae, Prevotellaceae, Ruminococcaceae and unclassified Bacteroidetes in the acidogenic reactor would have contributed to the improved sludge volatile solids degradation, and ultimately the overall 2-phase system＇s performance. Syntrophic acetogenic microorganisms were absent in the acidogenic reactor but present in the downstream methanogenic reactor, indicating the retention of various metabolic pathways also found in a single-stage system. The determination of key microorganisms further expands our understanding of the complex biological functions in AD process.

Selective hydroconversion of 2-methylfuran to pentanols on MWNT-supported Pt catalyst at ambient temperature

The selective hydrogenolysis of C–O bond in furfural and its derivatives provides a sustainable route for transforming biomass-derived feedstocks into valued chemicals. Currently, the development of efficient catalysts which can effectively cleavage C–O bond under mild conditions remains a critical challenge. The present work reports Pt catalysts supported on multi-walled carbon nanotubes (MWNT) which are active in 2-methylfuran (2-MF) hydrogenolysis to form pentanols in liquid phase under mild conditions. The impact of various catalyst supports, active metals and reaction conditions in terms of metal loadings, solvent, time, pressure, etc., were explored.The 5 wt%Pt/MWNT catalyst demonstrated an excellent activity and selectivity with 100%2-MF conversion and53%pentanols (POLs) yield under 1 MPa H;at an exceptional low temperature of 25℃. The reaction mechanism was studied combing both the reactivity tests and characterization results, and it is found that the better catalytic performances of Pt/MWNT were correlated closely to the size of Pt nanoparticles and their interactions with the underlying MWNT support. Accordingly, a reaction pathway involving the adsorption of 2-MF parallel to the Pt nanoparticles and its subsequently selective C–O hydrogenolysis was proposed. This work showcases a promising catalyst for room-temperature biofuel production.

基于石墨烯-二硫化钼复合气凝胶的多功能吸附材料的制备及其在水污染处理方面的应用（英文）

三维碳基多孔材料因其独特的结构和超高的吸附性能,已成为最有水污染处理应用前景的吸附材料之一.本文通过有效的调控,合成了多种具有不同孔道结构和成分组成的石墨烯-二硫化钼复合气凝胶材料.这种材料在吸附重金属离子,有机染料,油及有机溶剂方面都有很多优异的表现.通过调控二硫化钼的比例,可以有效改善材料的吸附性能.得益于此,其吸附重金属汞离子的效率可以达到1245 mg g^(-1).