Search

The sequence of sulfidation and NaOH etching plays an important role in the morphological structure of CoFeAl LDH evolved catalysts and thus results in a completely different water splitting activity in an alkaline solution.

Lithium–sulfur (Li–S) battery is labeled as a promising high-energy-density battery system, but some inherent drawbacks of sulfur cathode materials using relatively complicated techniques impair the practical applications. Herein, an integrated approach is proposed to fabricate the high-performance rGO/VS4/S cathode composites through a simple one-step solvothermal method, where nano sulfur and VS4 particles are uniformly distributed on the conductive rGO matrix. rGO and sulfiphilic VS4 provide electron transfer skeleton and physical/chemical anchor for soluble lithium polysulfides (LiPS). Meanwhile, VS4 could also act as an electrochemical mediator to efficiently enhance the utilization and reversible conversion of LiPS. Correspondingly, the rGO/VS4/S composites maintain a high reversible capacity of 969 mAh/g at 0.2 C after 100 cycles, with a capacity retention rate of 82.3%. The capacity fade rate could lower to 0.0374% per cycle at 1 C. Moreover, capacity still sustains 795 mAh g–1 after 100 cycles in the relatively high-sulfur-loading battery (6.5 mg/cm2). Thus, the suggested method in configuring the sulfur-based composites is demonstrated a simple and efficient strategy to construct the high-performance Li–S batteries.

Flexible aqueous energy storage devices with high security and flexibility are crucial for the progress of wearable energy storage. Particularly, aqueous rechargeable Ni-Fe batteries owning a large theoretical capacity, low cost and outstanding safety characteristics have emerged as a promising candidate for flexible aqueous energy storage devices. Herein, Cu-doped Fe3O4 (CFO) with 3D coral structure was prepared by doping Cu2+ based on Fe3O4 nanosheets (FO). Furthermore, the Fe-based anode material (CFPO) grown on carbon fibers was obtained by reconstructing the surface of CFO to form a low-crystallization shell which can enhance the ion transport. Excitingly, the newly developed CFPO electrode as an innovative anode material further exhibited a high capacity of 117.5 mAh g−1 (or 423 F g−1) at 1 A g−1. Then, the assembled aqueous Ni-Fe batteries with a high cell-voltage output of 1.6 V deliver a high capacity of 49.02 mAh g−1 at 1 A g−1 and retention ratio of 96.8% for capacitance after 10 000 continuous cycles. What's more, the aqueous quasi-solid-state batteries present a remarkable maximal energy density of 45.6 Wh kg−1 and a power density of 12 kW kg−1. This work provides an innovative and feasible way and optimization idea for the design of high-performance Fe-based anodes, and may promote the development of a new generation of flexible aqueous Ni-Fe batteries.

Certain anaerobic microbes with the capability to colonize in tumor microenvironment tend to express the heterologous gene in a sustainable manner, which would inevitably comprise the therapeutic efficacy and induce off-tumor toxicity in vivo. To improve the therapeutic precision and controllability of bacteria-based therapeutics, Escherichia coli Nissle 1917 (EcN) engineered to sense blue light and release the encoded flagellin B (flaB), is conjugated with lanthanide upconversion nanoparticles (UCNPs) for near-infrared (NIR) nano-optogenetic cancer immunotherapy. Upon 808 nm photoirradiation, UCNPs emit at the blue region to photoactivate the EcN for secretion of flaB, which subsequently binds to Toll-like receptor 5 expressed on the membrane of macrophages for activating immune response via MyD88-dependent signal pathway. Such synergism leads to significant tumor regression in different tumor models and metastatic tumors with negligible side effects. Our studies based on NIR nano-optogenetic platform highlight the rational of leveraging the optogenetic tools combined natural propensity of certain bacteria for cancer immunotherapy. This article is protected by copyright. All rights reserved.

Electrocatalytic water splitting is a promising route for the generation of clean hydrogen. However, the anodic oxygen evolution reaction (OER) suffers greatly from low reaction kinetics and thereby hampers the energy efficiency of alkaline water electrolysers. In recent years, tremendous efforts have been dedicated to the pursuit of highly efficient, low cost and stable electrocatalysts for oxygen evolution reaction. Herein, an amorphous FeOOH roughened capillary-liked CoAl layered double hydroxide (LDH) catalyst grown on nickel foam (denoted as FeOOH–CoAl LDH/NF) was reported for OER electrolysis. The developed FeOOH–CoAl LDH/NF electrode shows excellent OER activity with overpotentials of 228 mV and 250 mV to deliver a current density of 50 mA cm−2 and 100 mA cm−2 in 1.0 M KOH solution, respectively, ranking it one of the most promising OER catalysts based on transition-metal-based LDH. This is owed to the formed capillary-liked hierarchy structure with high-porosity as well as the strong electronic interaction between FeOOH and CoAl LDH. The developed morphological engineering approach to build hierarchal porous structures together with facile amorphous FeOOH modification may be extended to other layered double hydroxide catalyst for enhanced OER activities.

CdS is widely used in the field of photocatalysis owing to its excellent photocatalytic H2 evolution (PHE) activity, but the photocatalytic stability of CdS is inhibited because of the drawback of photocorrosion. Under light, the introduction of WS2 cocatalysts induces the growth of layered CdS on the WS2 nanosheets. Through the photocatalytic activity measurement, after adding ultrathin WS2 nanosheets, the amount of H2 released can reach 139.15 mmol g−1 after 7 h, which is 11.3 times higher than that of pure CdS nanoparticles. Furthermore, these composites illustrate excellent light absorption performance in the near-infrared region. A heterojunction is formed between WS2 and CdS under light, which greatly promotes the mobility of interface carriers and limits the recombination of photogenerated carriers. The hydrogen evolution output remains stable after 42 h, and the photocorrosion problem is effectively suppressed. In this work, we provide an effective and simple method to improve photocatalytic activity and stability, which is beneficial to the practical development of photocatalysis.

Hollow nanostructures have attracted increasing research interest in hydrogen evolution reaction owing to their unique structural features. Herein, Ni–Co mixed metal phosphide hollow and porous polyhedrons was successfully composited (expressed as NiCoP). Benefiting from the synergistic effects of ZIF-67 by doping Ni elements and the well-defined hollow and porous structure, the as-synthesized NiCoP hollow and porous polyhedrons exhibit better electrochemical properties and mechanical stability for hydrogen evolution reaction over a pH-universal range, with a small Tafel slopes of 72, 101, 176 mV/dec, and a low overpotential of 82, 102, 261 mV at a current density of 10 mA/cm2 in 0.5 mol/L H2SO4, 1 mol/L KOH and 1 mol/L phosphate buffer solution (PBS). This general strategy can also be applied to fabricate other hollow cobalt-based phosphides and MOFs-derived materials for HER.

The use of cheap and efficient electrocatalyst for the production of hydrogen is the key to solving the current energy crisis. Herein, we used a two-step hydrothermal process to fabricate noble-metal-free 3D net-like Ni

Layered double hydroxides (LDHs), a class of anionic clays consisting of brucite-like host layers and interlayer anions, have been widely investigated in the last decade due to their promising applications in many areas such as catalysis, ion separation and adsorption. Owing to the highly tunable composition and uniform distribution of metal cations in the brucite-like layers, as well as the facile exchangeability of intercalated anions, LDHs can be modified and functionalized to form various nanostructures/composites through versatile processes such as anion intercalation and exfoliation, decoration of nanoparticles, self-assembly with other two-dimensional (2D) materials, and controlled growth on conductive supports (e.g., nanowire arrays, nanotubes, 3D foams). In this article, we briefly review the recent advances on both the LDH nanostructures and functionalized composites toward the applications in energy conversion, especially for water oxidation.

Metallic Ag0 intercalated CoAl-layered double hydroxides (CoAl LDHs) have been successfully synthesized in situ through a simple redox process with ethylene glycol (EG) and triethanolamine (TEOA). The Ag(CN)2− anion-exchanged precursor was reduced by EG to form metallic Ag0. Furthermore, the effect of TEOA on confining the particle size of Ag0 was demonstrated. The oxygen reduction reaction (ORR) property of metallic Ag0 intercalated CoAl LDHs was examined in alkaline aqueous solution. A typical sample synthesized by the addition of TEOA for 180 min exhibited excellent ORR catalytic activity with a high current density of 5.5 mA cm−2 at 0.2 V (vs. a reversible hydrogen electrode (RHE)) and good stability. Koutecky–Levich (K–L) calculations and rotating ring-disk electrode (RRDE) measurements further revealed that the ORR of the as-prepared catalyst proceeded mainly via an almost ideal four-electron transfer process. The enhanced electrocatalytic activity was ascribed to the intercalated Ag0, confined nanoparticle size and the expanded interlayer space, which effectively facilitate the reactant transfer and electron migration.

ZnCo2S4 nanoneedle clusters are uniformly grown as a core on foamed nickel and then are coated with Ni(OH)2 nanosheets as shell layers. The formed ZnCo2S4@Ni(OH)2 core–shell structures as electrode materials exhibit high specific capacitance (1193 C g−1 at 1 A g−1) and superior cycle rate performance (a capacity retention rate of 92% after 8000 cycles). The ZnCo2S4@Ni(OH)2//AC asymmetric supercapacitor composed of AC//NF as the negative electrode, ZnCo2S4@Ni(OH)2 as the positive electrode, porous glass fiber paper as the separator and 3 mol L−1 KOH as the electrolyte shows a specific capacitance of 215 F g−1 at 1 A g−1 with 70% capacitance retention and 100% coulombic efficiency even after 5000 cycles at a scan rate of 5 A g−1, evidencing the excellent energy storage capacitance and electrochemical performance. Besides, the ZnCo2S4@Ni(OH)2//AC device exhibits an exceptional energy density of ∼44 W h kg−1 at a power density of ∼0.83 kW kg−1.

The serious environmental pollution have been one of the most important scientific problems to be urgently solved in the social development process. Metal silicates have attracted extensive interest due to their unique structure and promising properties in adsorption. Rice husks are suitable natural reservoirs for the preparation of high value-added nanostructured silicate-based adsorbents. Inspired by this proposal, we herein reported a facile and general strategy to fabricate flower-like magnesium silicate with ultrathin nanosheets from the low-cost rice husks as sustainable silicon sources. The as-prepared magnesium silicate was used as an adsorbent to test its adsorption performance towards U(VI) remove. Dependent on batch adsorption experiments, the adsorption behavior and removal efficiency of U(VI) under various environmental conditions (e.g., pH, contact time and solid content) were simulated systematically. The results showed that the adsorptive properties were highly pH dependent. The adsorption system obeyed the pseudo-second-order kinetic models. The adsorption data were well fitted with the Langmuir isotherms, and the maximum adsorption capacity was up to ~663.7 mg/g.

The reasonable design of the structure and composition of catalysts was essential to improve the catalytic performance of advanced oxidation processes (AOPs). Herein, we reported a simple strategy to synthesize hierarchical Co3O4-C@CoSiOx yolk-shell nanoreactors with multiple active components by using metal–organic frameworks (MOFs). The novel nanoreactors are further used to activate peroxymonosulfate (PMS) for ciprofloxacin (CIP) degradation. The effects of reaction parameters (pH value, co-existing ions, reaction temperature, etc.) on CIP degradation were systematically investigated. Especially, ∼98.2% of CIP was degraded within 17 min under the optimal conditions, together with the low cobalt leaching and excellent reusability. The appreciable catalytic performance improvement might be due to the synergistic effect of the structure and component design: (1) the hierarchical yolk-shell structure endowed the catalyst with high surface area (∼232.47 m2/g) and fully exposed active sites; (2) abundant highly active ≡Co-OH+ were formed on the surface of CoSiOx; (3) the presence of oxygen vacancies and nitrogen-doped carbon promoted the decomposition of PMS through a non-radical process. The results revealed both the radical (SO4∙-, ∙OH and O2∙-) and non-radical (1O2 and direct charge transfer) should be responsible for the CIP degradation. Moreover, the possible degradation pathways of CIP were proposed through the identification of intermediates using LC-MS/MS techniques and density functional theory (DFT) calculation. Our work highlights that multi-component catalysts derived from MOFs with novel structure have broad application prospects in AOPs.

Epitaxial growth of an inert shell around the optical active lanthanide upconversion nanoparticles (UCNPs) is a general strategy to enhance their brightness. Yet, its potential as a tool in multiplexing emission tailoring has rarely been reported. Here, by developing the atomic vacancies into color selectivity actuators, we present an efficient strategy to achieve inert-shell-modulated multiplexing upconversion in 1540 nm activated UCNPs. Artificially generated fluoride atomic vacancies, owing to the decreased NaOH/NH4F dosage during shell growth, reduce the coordination number of Y-F and lattice densities in the inert shell, leading to the core-engineered shell nanoparticles with distinctive emission profiles. The multicolor tailoring is independent of shell thickness and can be readily applied to Lu3+/Gd3+-based shells. The upconversion emission can be exploited to visualize in security decoding and in vivo multiplexing bioimaging. This method of regulating atomic vacancies based on the inert-shell engineering opens new insights of upconversion modulation in core-shell lanthanide nanostructures.

The fatigue damage mechanisms of 3D woven composites are very complex. In this work the tension–compression (T-C) fatigue damage evolution of 3D woven composites is investigated using a multi-scale method. To avoid the buckling failure during the T-C fatigue tests, a novel anti-buckling device is designed. The authors combine the macro damage information (i.e., axial stiffness and surface temperature) and the meso-damage information (i.e., detection results by synchrotron radiation computed tomography (SRCT)) to investigate the fatigue damage evolution. The results show that the T-C fatigue process can be divided into two stages. The stiffness decreases slowly in a linear form in Stage I, and then decreases rapidly to final failure in Stage II. Most of the fatigue damage occurs in Stage II. The SRCT results can reveal the damage modes in either fatigue stage, in which the warp yarn breakage is the critical damage mode.

Amorphous/crystalline heterophase composites possess expansive reaction interfaces and abundant oxygen vacancy defects, providing novel electron-hole transmittal mode and significantly facilitating the surface adsorptions and redox reactions. Herein, galvanic replacement reaction (GRR) was used to construct amorphous SnOx/ crystalline Co3O4 multishell heterostructures. Characterizations indicated the continuous transition from Co3O4 to amorphous SnOx on each shell, generating abundant amorphous/crystalline interfaces. Moreover, the oxygen vacancy defects concentration also increased with the GRR proceeding. Benefitting from theses, the surface oxygen adsorption was facilitated due to more surface active sites and enhanced carrier densities. However, with further increasing the reaction time, decreased adsorbed oxygen concentrations were detected, owning to the unexpected high potential barriers induced by excessive heterojunctions. Gas sensing results showed that the sensors with 1 h GRR exhibited the best sensing performance with an exceptional response (1268) to 100 ppm formaldehyde gas and low detection limit (21 ppb) at low working temperatures (100 °C). The synergistic effects between oxygen vacancy defects and amorphous/crystalline heterophase interfaces on the superior gas sensing behaviors were also investigated. Most importantly, results presented will shed lights on the rational design of highly sensitive gas sensors through amorphous/crystalline interfaces constructions.

In this work, MoS2 nanosheets were obtained successfully using the liquid phase exfoliation method assisted by formamide solvothermal treatment. The exfoliation efficiency in N-methyl-2-pyrrolidone (NMP) was enhanced by the synergetic effect of easier intercalation of polar solvent and higher repulsive force of the treated bulk MoS2. The exfoliated MoS2 nanosheets were assembled alternately with H3Mo12O40P (PMo12) into a multilayer heterostructure by the layer-by-layer (LBL) method, in which PMo12 with high electron mobility bridges the adjacent catalytically active MoS2 layers. Based on the heterostructure, the electrocatalytic performance for hydrogen evolution was substantially enhanced over multilayer MoS2 nanosheets alone. Moreover, it was found that the electrocatalytic performance was influenced by the layer number, indicating that an optimum balance between the mass transfer (MoS2 layer) and electron conductivity (PMo12 layer) was needed for the construction of efficient electrocatalysts. In addit...

ZnO/ZnFe2O4 hollow nanocages have been designed and synthesized through a metal organic frameworks route, which involves two steps including the synthesis of Fe(III)MOF-5 nanostructured cages precursors and the subsequent transformation to ZnO/ZnFe2O4 hollow nanocages by thermal annealing in air. The ZnO/ZnFe2O4 architecture is constructed by hollow nanocages with the scale around 100 nm. To demonstrate its functional properties, the as-prepared products are utilized as sensing material for gas sensor. Significantly, the ZnO/ZnFe2O4 hollow nanocages exhibit enhanced response to acetone (25.8) with the detection limit of 1 ppm at an optimum temperature of 290 °C toward its two individual compositions (ZnO nanocages (7.9) and ZnFe2O4 nanospheres (8.1)). Moreover, the response of the ZnO/ZnFe2O4 nanocages is even larger than that of other architectures, which follows the order hollow nanocages > double shell > hollow microsphere > hybrid hollow sphere > nanoparticle with rod. The remarkable gas sensing performance enhancement of ZnO/ZnFe2O4 nanocages can be attributed to the unique porous and hollow structure, heterojunction and high response/surface area ratio.

Robust and highly active photocatalysts, CdS@MoS2, for hydrogen evolution were successfully fabricated by one-step growth of oxygen-incorporated defect-rich MoS2 ultrathin nanosheets on the surfaces of CdS with irregular fissures. Under optimized experimental conditions, the CdS@MoS2 displayed a quantum yield of ∼24.2% at 420 nm and the maximum H2 generation rate of ∼17203.7 umol/g/h using Na2S–Na2SO3 as sacrificial agents (λ ≥ 420 nm), which is ∼47.3 and 14.7 times higher than CdS (∼363.8 μmol/g/h) and 3 wt % Pt/CdS (∼1173.2 μmol/g/h), respectively, and far exceeds all previous hydrogen evolution reaction photocatalysts with MoS2 as co-catalysts using Na2S–Na2SO3 as sacrificial agents. Large volumes of hydrogen bubbles were generated within only 2 s as the photocatalysis started, as demonstrated by the photocatalytic video. The high hydrogen evolution activity is attributed to several merits: (1) the intimate heterojunctions formed between the MoS2 and CdS can effectively enhance the charge transfer abil...

A NiS-H 3 Mo 12 O 40 P (PMo 12 ) composite counter electrode was successfully fabricated by periodic potential reversal method. Up to now, it is the first time that NiS-PMo 12 composite counter electrode was fabricated and was used in dye-sensitized solar cells. The scanning electron microscope and energy dispersive X-ray spectroscopy were applied to study the morphology and component. The cyclic voltammetry and Tafel polarization measurement results show that the electrocatalytic ability for I 3 − reduction of the composite counter electrode is comparable to that of a Pt counter electrode. The enhanced efficiency is benefit from the high electrocatalytic activity and electron mobility of the PMo 12 . In addition, the composite counter electrode possess low cost.

CuxO (CuO, CuO/Cu2O, and Cu2O) nanostructures have been controllably synthesized through a facile low-temperature solution method. The morphologies and compositions of CuxO nanostructures were well controlled by tuning the reductant amount of hydroxylamine hydrochloride, which experienced the transformation of nanosheets to octahedrons as well as the phase change of CuO to Cu2O. The as-grown samples showed photodegradation selectivity to MO (maximum photocatalytic efficiency of 52% for methyl orange (MO) and 16% for rhodamine B (RhB) after 180 min photodegradation) and different photocatalytic activities in the absence or presence of H2O2 (62% without H2O2 and 82% with H2O2). The morphological transformations of as-grown samples were observed after the photocatalytic measurement in the presence of H2O2. The structural and morphological features after photodegradation were studied by XPS, SEM, and TEM investigations, revealing the possible mechanism of the as-prepared samples whereby the photodegradation of organic dyes occurred on the surface with respect to the adsorption ability, structure, and morphology of CuxO. In addition, H2O2 played an important role in the photodegradation of organic dyes.

Metallic Ag0 intercalated CoAl-layered double hydroxides (CoAl LDHs) have been successfully synthesized in situ through a simple redox process with ethylene glycol (EG) and triethanolamine (TEOA). The Ag(CN)2- anion-exchanged precursor was reduced by EG to form metallic Ag0. Furthermore, the effect of TEOA on confining the particle size of Ag0 was demonstrated. The oxygen reduction reaction (ORR) property of metallic Ag0 intercalated CoAl LDHs was examined in alkaline aqueous solution. A typical sample synthesized by the addition of TEOA for 180 min exhibited excellent ORR catalytic activity with a high current density of 5.5 mA cm-2 at 0.2 V (vs. a reversible hydrogen electrode (RHE)) and good stability. Koutecky-Levich (K-L) calculations and rotating ring-disk electrode (RRDE) measurements further revealed that the ORR of the as-prepared catalyst proceeded mainly via an almost ideal four-electron transfer process. The enhanced electrocatalytic activity was ascribed to the intercalated Ag0, confined nanoparticle size and the expanded interlayer space, which effectively facilitate the reactant transfer and electron migration.

Fabricating catalysts with dual active sites is an effective approach for boosting the catalytic activities. In this work, a highly active catalyst with Co nanoparticles decorating on interconnected N-doped carbon nanotube clusters (Co@NCNTS) was synthesized by directly heating the ZIF-67 precursor in H2/Ar atmosphere. The Co nanoparticles exhibited small particle sizes (7–11 nm) and high dispersions, which will prevent the particles from coalescence and agglomeration. In addition, the intertwined NCNTS network could also provide a long-term conductivity, which will facilitate the transfer of charge carriers and effectively enhance the catalytic performance. After that, the catalytic reduction performance of the catalysts to 4-nitrophenol in the presence of NaBH4 solution was also investigated. As expected, the as-synthesized Co@NCNTS catalyst exhibited a superior catalytic reduction ability to 4-nitrophenol in the presence of NaBH4 solution with an almost 100% conversion ratio and a high apparent kinetic rate constant k of 0.37 min−1. Furthermore, the pristine NCNTS also exhibited well catalytic reduction performance to 4-nitrophenol with a k constant of 0.09. The synergetic effect between Co nanoparticles and NCNTS could effectively boost the catalytic reduction performance. Thus, the excellent catalytic performance could own to the confinement effect of ZIF-67 precursors, high conductivity and synergetic effect between Co nanoparticles and NCNTS.

A method combining mechanical testing, infrared thermography (IRT) and synchrotron radiation computed tomography (SRCT) is proposed for the damage evolution of 3D woven carbon/epoxy composites under tension-tension (T-T) fatigue loading. To study the relationship between the damage evolution and the stiffness degradation, fatigue tests of six specimens are carried out to different stages before detection by SRCT and optical microscope. The detected results have revealed how cracks initiate, distribute and develop with increasing fatigue cycles. Particularly, the effects of fiber yarn undulation and twist caused during the manufacturing process are discussed.

Hollow cubic Zn 2 SnO 4 sub-microstructures (ZTOs) were fabricated via a one-pot hydrothermal method. The samples were carefully characterized and the experimental results show that the as-prepared ZTOs possess hollow cubic morphology with the length of 500 nm and a relatively rough surface which may endow them high surface areas. The photocatalytic activities were evaluated by the degradation of methylene blue (MB), methylene orange (MO), and rhodamine B (RhB) and the results exhibit a much higher selectivity to the degradation of MB (95%) by Zn 2 SnO 4 than that of MO (70%), RhB (81%) and ZnSn(OH) 6 (MB 20%) in 20 min.

TiO2 nanorods arrays (TiO2 NRAs):Eu3+, Tb3+ decorated with Cs2CO3/CdS grown on carbon textiles coated with a TiO2–graphene (TiO2-G) thin film (TiO2-G/TiO2 NRAs:Eu3+, Tb3+/Cs2CO3/CdS) was fabricated. The as-prepared sample exhibits an excellent photodegradation performance under xenon (Xe) lamp light irradiation. The result indicates that the presence of Eu3+, Tb3+ can be excited by ultraviolet light to produce a high intensity visibe light absorbed by CdS, which can generate more photogenerated electron hole pairs. In addition, the presence of graphene is an important factor in accelerating the transferring of photogenerated electron to carbon textiles for photocatalytic reaction. This work can offer an alternative route for designing a hybrid structure system to utilize effectively broad-spectrum solar light and suppress the recombination of photogenerated electron–hole pairs.

A new architecture of one dimensional ordered TiO2 nanorods modified by graphene oxide (GO) was assembled. The GO as the higher carrier mobility can reduce the recombination of carriers, which is more favourable for the methy orange (MO) degradation. Incorporating GO with the unblocked passageway for carrier transportation of the TiO2 nanorods can separate the transport pathway of electron and hole effectively. Furthermore, the large surface areas of TiO2 nanorods grown on the GO are beneficial to the enhancement of photocatalytic properties, and the reasonable band energy level can be obtained for the architecture, which is favorable for enhancing carrier separation and transportation. Finally, the higher transparency of the structure can enhance the light absorption. The photocatalyst grown on FTO substrates makes it easier to collect and recycle.

A hierarchical structure composed of porous TiO2:Al2O3:Eu3+ nanoparticles (NPs) and vertically grown one-dimensional TiO2:Er3+,Yb3+ nanorods (NRs) on fluorine doped tin oxide (FTO) substrates coated with a TiO2:graphene (G) seed layer was investigated for use in photoanodes for dye sensitized solar cells (DSSCs). The DSSCs assembled with this hierarchical structure exhibit an outstanding power conversion efficiency of 4.58%, which is superior to that of the devices based on pure TiO2. This high performance can be attributed to the spectrum modifications achieved by utilizing the upconversion (UC) material TiO2:Er3+,Yb3+ and the downconversion (DC) material Al2O3:Eu3+, which facilitate the light harvesting of solar cells via converting near infrared (NIR) and ultraviolet (UV) radiation to visible emission, respectively. Moreover, the TiO2:G layer provides faster electron transport from TiO2 to FTO for the high carrier mobility of G. Moreover, the one-dimensional nanorod structure can offer direct electrical pathways for photogenerated electrons as well as enhance the light scattering capabilities of photoanodes. This study indicates that the TiO2:G/TiO2:Er3+,Yb3+ NRs/TiO2:Al2O3:Eu3+ hierarchical structure has the potential to improve the performance of DSSCs.

TiO2 nanorod arrays (NRAs) filled with CH3NH3PbI3 were coated by Cu2O, which was fabricated on carbon fiber to form the photocatalyst TiO2 NRAs/CH3NH3PbI3/Cu2O. The morphology and structure of the as-obtained samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The ultraviolet-visible (UV-vis) absorption measurements and photocurrent test revealed that the CH3NH3PbI3 layer can provide a greatly enhanced light harvesting efficiency. The I–V curves and electrochemical impedance spectra (EIS) analysis confirmed that the TiO2 NRAs/CH3NH3PbI3/Cu2O hybrid structure favors electron transfer. The TiO2 NRAs/CH3NH3PbI3/Cu2O structure exhibits enhanced photocatalytic activity with good recyclability under Xe lamp irradiation. The experimental results indicate that the better photocatalytic performance is ascribed to the higher carrier separation and transportation, higher specific surface area and the broadened absorption spectrum.

Dye-sensitized solar cells (DSSCs) have attracted extensive attention as one of the promising alternatives to silicon solar cells. However, DSSCs have a maximum absorption in the visible light of solar spectrum, which confines their power conversion efficiency. Lots of research efforts have been focused on extending light absorption to enhance the conversion efficiency. Rare earth ion doped up/down conversion materials is an available approach to compensate for the non-absorbable wavelength region of DSSCs via converting ultraviolet and near-infrared radiation to visible emission. In addition to the light-harvesting enhancement, light-scattering effect and recombination loss can also be achieved in DSSCs by utilizing upconversion (UC) or downconversion (DC) materials. Moreover, the introduction of UC or DC facilitates to improve the stability of solar cells. In this review paper, the performance of dye-sensitized solar cells based on up or down conversion materials will be introduced.

In this paper, a novel mesoscopic progressive damage model is proposed to investigate the effective properties and damage mechanisms of 3D angle-interlock woven composites. The damage activation is based on the three-dimensional version of Puck criterion. Given that there may be multiple cracks in the transverse direction of the fiber yarns, a set of fracture angle-dependent damage variables are introduced to eliminate the stress abnormal phenomenon. In addition, an innovative exponential damage evolvement scheme, based on the equivalent displacement and stress, characteristic element length and fracture toughness, is proposed to govern the damage variables. Furthermore, a representative mesoscopic volume cell model, accounting for the fluctuation, distortion and actual cross-section size of fiber yarns, is constructed to represent the realistic interlaced architecture of the woven composites. The anisotropic damage model is applied to investigate the failure behavior of the 3D woven composites subjected to uniaxial tensile loading along the warp and weft directions. Some typical quasi-static tension experiments are performed to validate the accuracy of the simulations. The numerical predictions including failure strength and damage accumulation process are coincident with the corresponding experimental results.