Biomass seaweed-derived n itrogen self-doped porous carb on anodes for sodium-ion batteries:Insights into the structure and electrochemical activity

Sustainable transformation and efficient utilization of biomasses and their derived materials are environ-mentally as well as economically compliant strategies.Biomass seaweed-derived nitrogen self-doped porous carbon with tailored surface area and pore structures are prepared through carb on izatio n and activation.The in fluence of carb on ization temperature on morphology,surface area,and heteroatom dopants are investigated to optimize sodium-ion storage capability.Seaweed-derived nitrogen selfdoped activated carbon(SAC)as anode materials for sodium-ion batteries exhibits remarkable reversible capacity of 303/192 mAh g^(-1) after 100/500 cycles at current densities of 100/200 mA g^(-1) respectively,and a good rate capability.The interconnected and porous conducting nature along with the heteroatom dopant role in creating defective sites and charge stabilization are favorable for ion storage and diffusion and electron transport,indicating the electrodes can offer improved electrochemical performances.In addition,post-mortem analysis of the cycled carbon electrodes through ex-situ tools demonstrates the sodium-ion storage mechanism.

Ti^(3+) self-doped TiO_2 photoelectrodes for photoelectrochemical water splitting and photoelectrocatalytic pollutant degradation

To improve the harvesting of visible light and reduce the recombination of photogenerated electrons and holes, Ti3+ self-doped TiO2 nanoparticles were synthesized and assembled into photoanodes with high visible light photoelectrochemical properties. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectra, electron resonance spectroscopy and energy dispersive X-ray spectra were used to characterize the structure, crystallinity, morphology and other properties of the obtained nanoparticles. UV-visible diffuse reflectance spectra showed that the Ti3+ self-doped TiO2 nanoparticles had a strong absorption between 400 and 800 nm. Moreover, when hydrothermal treatment time was prolonged to 22 h, the heterogeneous junction was formed between the anatase and rutile TiO2, where the anatase particles exposed highly active {001} facets. Under visible light irradiation, the Ti3+ self-doped TiO2 electrode exhibited an excellent photoelectrocatalytic degradation of rhodamine B (RhB) and water splitting performance. Intriguingly, by selecting an appropriate hydrothermal time, the high photoconversion efficiency of 1.16% was achieved. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Two-dimensional ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes for enhanced photocatalytic water splitting hydrogen production

Two-dimensional (2D) ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes were fabricated using an electrospinning-hydrothermal treatment-reduction method.Bare TiO2 nanotubes were fabricated via electrospinning.Then,2D MoS2 lamellae were grown on the surface of the nanotubes and Ti^3+/Ov ions were introduced by reduction.The photocatalytic performance of the 2D MoS2/Ti^3+-TiO2 nanotubes was^15 times better than that of TiO2.The HER enhancement of the MoS2/Ti^3+-TiO2 nanotubes can be attributed to the Pt-like behavior of 2D MoS2 and the presence of Ti^3+-ions,which facilitated the quick diffusion of the photogenerated electrons to water,reducing the H2 activation barrier.The presence of Ov ions in the nanotubes and their hollow structure increased their solar utilization.

Effects of Elemental Chemical State in NiFe2O4@TiO2 on the Photocatalytic Performance

The elemental chemical state of NiFe2O4@TiO2 was changed by the reduction in order to investigate its effects on the photocatalytic performance.The synthesized NiFe2O4@TiO2 samples were characterized by means of X-ray diffraction (XRD),high-resolution transmission electron microscopy (HRTEM),Fourier-transform infrared spectroscopy (FT-IR),X-ray photoelectron spectroscopy (XPS),magnetic and photocatalytic measurements.Unexpectedly,the reduction reaction does not produce oxygen vacancies Ov and TiOx in the TiO2 lattice.The optimal catalyst was obtained at the reducing temperature of 800℃,and its degradation efficiency De to the methylene blue and reaction rate constant Kapp are the highest,reaching 99.9% and 3×10^-2 min-1,respectively.The reason could not be explained by both the visible light absorption and the appropriate amount of Ov and TiOx.Instead,the lowest ratios of TiOH and Ti-O-Fe(Ni) may be responsible for the optimum photocatalytic performance.

Light-responsive color switching of self-doped TiO_(2-x)/WO_(3)·0.33H_(2)O hetero-nanoparticles for highly efficient rewritable paper

Smart materials that reversibly change color upon light illumination are widely explored for diverse appealing applications.However,light-responsive color switching materials are mainly limited to organic molecules.The synthesis of inorganic counterparts has remained a significant challenge because of their slow light response and poor reversibility.Here,we report a seeded growth strategy for the synthesis of TiO_(2-x)/WO_(3)·0.33H_(2)Ohetero-nanoparticles(HNPs)with networked wire-like structure of〜10 nm in diameters that enable the highly reversible light-responsive color switching properties.For the TiO_(2-x)/WO_(3)·0.33H_(2)OHNPs,T P species self-doped in TiO_(2-x)nanoparticles(NPs)act as efficient sacrificial electron donors(SEDs)and Ti-O-W linkages formed between TiO2-x and WO30.33H2O NPs ensure the nanoscale interfacial contact,endowing the HNPs enhanced photoreductive activity and efficient interfacial charge transfer upon ultraviolet(UV)illumination to achieve highly efficient color switching.The TiO_(2-x)/WO_(3)·0.33H_(2)OHNPs exhibits rapid light response(<15 s)and long reversible color switching cycles(>180 times).We further demonstrate the applications of TiO_(2-x)/WO_(3)·0.33H_(2)O HNPs in ink-free,light-printable rewritable paper that can be written on freehand or printed on through a photomask using UV light.This work opens an avenue for designing inorganic light-responsive color switching nanomaterials and their smart applications.

Ti^(3+) self-doped TiO_(2) as a photocatalyst for cyclohexane oxidation under visible light irradiation

Most of TiO_(2) particles can be used as a photocatalyst for the selective oxidation of cyclohexane under ultraviolet light illumination.In this paper,Ti^(3+) self-doped TiO_(2) submicron-sized particles(i.e.,Ti^(3+)/TiO_(2) SMP)were used as a catalyst for visible-light driven photocatalytic cyclohexane oxidation.The microstructure and properties of the Ti^(3+)/TiO_(2) SMP were characterized by X-ray diffraction(XRD),UVevisible diffuse reflection(UVeVis DRS),scanning electron microscopy(SEM),electron paramagnetic resonance(EPR),solid-state photoluminescence spectroscopy(PLS)and X-ray photoelectron spectroscopy(XPS).The Ti^(3+)/TiO_(2) SMP exhibits good visible-light driven photocatalytic performances for cyclohexane oxidation with cyclohexanone as a dominate product.Effects of solvent,reaction temperature,reaction time and oxygen pressure on the formation of cyclohexanone were investigated.The cyclohexane oxidation over the Ti^(3+)/TiO_(2) SMP photocatalyst using carbon tetrachloride as a solvent under the optimal conditions presents a greater selectivity to cyclohexane(i.e.,95.1%).Based on the controlled experimental results with different radical scavengers,the hole(h^(+))is critical for the activation of cyclohexane.

Tuning the structures of polypyridinium salts as bifunctional cathode interfacial layers for all-solution-processed red quantum-dot light-emitting diodes

Self-doping cathode interfacial layers(CILs) with both favorable electron injection and transport characteristics meet the key requirement for realizing high-performance optoelectronic devices with simplified structures. Herein, four different polypyridinium salts with tunable backbones, side chains and counterions are elaborately designed to afford them desirable film-forming property, polarity, structural rigidity and self-doping feature. All-solution-processed red quantum dot light-emitting diodes(QLEDs) employing them as bifunctional CILs render remarkably improved device performances in contrast to the typical CIL material of poly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)](PFN).The maximum external quantum efficiency of 2.74% achieved in this work represents one of the best values among the all-solution-processed QLEDs with individual organic CILs.

Thermally activated delayed fluorescence materials for nondoped organic light-emitting diodes with nearly 100%exciton harvest

High-performance nondoped organic light-emitting diodes(OLEDs)are promising technologies for future commercial applications.Herein,we synthesized two new thermally activated delayed fluorescence(TADF)emitters that enable us,for the first time,to combine three effective approaches for enhancing the efficiency of nondoped OLEDs.First,the two emitters are designed to have high steric hindrances such that their emitting cores will be suitably isolated from those of their neighbors to minimize concentration quenching.On the other hand,each of the two emitters has two stable conformations in solid films.In their neat films,molecules with the minority conformation behave effectively as dopants in the matrix composing of the majority conformation.One hundred percent exciton harvesting is thus theoretically feasible in this unique architecture of“self-doped”neat films.Furthermore,both emitters have relatively high aspect ratios in terms of their molecular shapes.This leads to films with preferred molecular orientations enabling high populations of horizontal dipoles beneficial for optical outcoupling.With these three factors,OLEDs with nondoped emitting layers of the respective emitters both achieve nearly 100%exciton utilization and deliver over 30%external quantum efficiencies and ultralow efficiency roll-off at high brightness,which have not been observed in reported nondoped OLEDs.

Black titanium dioxide nanomaterials for photocatalytic removal of pollutants:A review

Semiconductor photocatalysis is one of the most widely used environment-friendly technologies for removing various contaminants.As a well-developed photocatalyst,titanium dioxide(TiO_(2))still has limits in its wide bandgap and rapid recombination rate of photogenerated charge carriers.Recently,black TiO_(2)appears as a strong candidate in the improvement of sunlight harvesting,because of its excellent absorption capacity and utilization of solar radiation.Despite extensive applications in both environmental and energy fields,the use of black TiO_(2)as a photocatalyst in pollutant removal is ambiguous.The primary objective of the review is to comprehensively evaluate the applications of black TiO_(2)in photocatalytic removal of contaminants,including conventional organic contaminants,emerging contaminants,microbes,and heavy metals.The basic properties,photocatalytic mechanism,and synthesis of black TiO_(2)have been summarized and analyzed.Moreover,the stability and recoverability of black TiO_(2)have also been discussed.Finally,the perspectives of the application of black TiO_(2)in pollutant removal have been further discussed.

Investigation on morphology and broadband blue-white emission modification of La_(1–x)Bi_xOCl polycrystals

Tetragonal structure La1-xBixOCl polycrystals were prepared by solid state synthesis. With increase in bismuth content, the morphology of the prepared samples changed from non-oriented particles to layered crystals and the broadband blue-white emission from LaOCl polycrystals decreased dramatically. Comparative experiments and X-ray photoelectron spectroscopy（XPS） analysis indicated that the host emission more possibly originated from Cl self-doping in oxychloride crystals. According to a close composition relationship of the Cl self-doping behavior and crystal morphology, it was suggested that the La composition strengthened the interlayer interaction between Cl^– anion and crystal cell lamellar, hindering the orientation of LaOCl crystals. The results of our work would deepen the understanding of the orientation structure of tetragonal oxyhalides and offer an insight into the origin of its host luminescence.