Porous cerium dioxide hollow spheres and their photocatalytic performance

Uniform-sized and monodiperse cerium dioxide porous hollow spheres (CeO2-PH) based on the Ostwald ripening process were fabricated by a simple solvothermal method in the absence of any templates. The structure and morphology of CeO2-PH and CeO2-NP (cerium dioxide nanoparticles) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The average diameter of face-centered cubic (fcc) phase CeO2-PH was ca. 160 nm with a high specific surface area, and it is composed of small crystal grain particles (ca. 10 nm). Furthermore, CeO2-PH has high activity for the evaluation of acetaldehyde decomposition. Optical, defect, and chemical state properties were characterized by Raman spectra, ultraviolet-visible absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The presence of Ce3+ ions narrowed the band gap of CeO2-PH, resulting in the high light harvesting. The large amount of oxygen vacancy defects provided many activity sites on CeO2-PH in the photocatalytic process. The formation scheme and photocatalyic mechanism will be discussed in this paper

Synthesis of Y-doped CeO2/PCN nanocomposited photocatalyst with promoted photoredox performance

In this study, yttrium-doped CeO2 was introduced into polymeric carbon nitride (PCN) through one-step hydrothermal reaction to form the Y-doped CeO2/PCN (YCC) nanocomposited photocatalysts. Morphology of products was observed by emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). The structure of the products was characterized by X-ray diffractometer (XRD), FT-IR and Raman analysis. Optical absorption and band energy properties were investigated by UV–vis, PL and VB-XPS spectra. The X-ray photoelectron spectroscopy (XPS) results further revealed that the surface active oxygen and Ce3+ concentration of nanocomposited photocatalyst were significantly increased compared with pure CeO2 and PCN counterparts. The YCC composites exhibited excellent photoredox performance under visible light irradiation, affording to 5.73- and 3.74-fold higher for RhB degradation and proton photoreduction to produce H2 than that of pure CeO2. The Y-doped nanocomposited means adopted in this study not only improve the optical utilization of visible light, but also effectively inhibit the recombination of photogenerated charge carriers, which are conducive to promote the photoredox performance synergistically

High performance integrated photonic circuit based on inverse design method

The basic indexes of all-optical integrated photonic circuits include high-density integration, ultrafast response and ultra-low energy consumption. Traditional methods mainly adopt conventional micro/nano-structures. The overall size of the circuit is large, usually reaches hundreds of microns. Besides, it is difficult to balance the ultrafast response and ultra-low energy consumption problem, and the crosstalk between two traditional devices is difficult to overcome. Here, we propose and experimentally demonstrate an approach based on inverse design method to realize a high-density, ultrafast and ultra-low energy consumption integrated photonic circuit with two all-optical switches controlling the input states of an all-optical XOR logic gate. The feature size of the whole circuit is only 2.5 μm × 7 μm, and that of a single device is 2 μm × 2 μm. The distance between two adjacent devices is as small as 1.5 μm, within wavelength magnitude scale. Theoretical response time of the circuit is 150 fs, and the threshold energy is within 10 fJ/bit. We have also considered the crosstalk problem. The circuit also realizes a function of identifying two-digit logic signal results. Our work provides a new idea for the design of ultrafast, ultra-low energy consumption all-optical devices and the implementation of high-density photonic integrated circuits

Design and Synthesis of Sm, Y, La and Nd‐doped CeO2 with a broom‐like hierarchical structure: a photocatalyst with enhanced oxidation performance

CeO2 doped with various rare earth (RE) ions (Sm, Y, La and Nd) having a broom‐like hierarchical structure was successfully prepared by a template‐free hydrothermal method. The photooxidation performance of RE‐doped products was significantly better than that of pure CeO2, and comparative experiments showed that Sm‐doped CeO2 (SC) has superior photooxidation activity, resulting about 3.0‐times and 8.5‐times higher activities of bisphenol A (BPA) degradation and of acetaldehyde (CH3CHO) decomposition, respectively, than those of pure CeO2. Due to the incorporation of RE ions, the surface exposed cerium ions are partly substituted by those cations, resulting in a higher concentration of oxygen vacancies (Ov) in RE‐doped CeO2. The increased Ov can act as a trapping center for photo‐generated electrons to form a doping transition state between the conduction band (CB) and valence band (VB), which can restrict the recombination rate of electrons and holes effectively and lead to an outstanding enhancement of photooxidation performance. Furthermore, abundant highly reactive hydroxyl radicals (.OH) and superoxide radicals (.O2−), which are efficient intermediates with vivid oxidation ability, can further enhance the photocatalytic activity of RE‐doped CeO2. A cost‐effective strategy for designing CeO2‐based semiconductor photocatalysts doped with multitudinous RE ions that have enhanced photooxidation performance is presented in this paper

Dependence of photocatalytic activity on aspect ratio of a brookite TiO2 nanorod and drastic improvement in visible light responsibility of a brookite TiO2 nanorod by site-selective modification of Fe3+ on exposed faces

Exposed crystal face-controlled brookite titanium(IV) oxide (TiO2) nanorods with various aspect ratios were prepared by a hydrothermal process with or without PVA or PVP as an aspect reagent. The nanorod-shaped brookite TiO2 had larger {2 1 0} and smaller {2 1 2} exposed crystal faces, which were assigned by TEM with the SAED technique. Their aspect ratios were greatly influenced by the addition of PVA or PVP as an aspect ratio control reagent to the reaction solution used in the hydrothermal treatment. The photocatalytic activity for decomposition of acetaldehyde increased with increase in the aspect ratio because the surface area ratio of {2 1 0} to {2 1 2} exposed crystal faces, which are attributed to reduction and oxidation sites, respectively, became more optimal. The {2 1 2} exposed crystal faces of surface-controlled brookite TiO2 were site-selectively modified with trivalent iron(III) (Fe3+) ions by utilizing the adsorption property of iron(III)/iron(II) (Fe3+/Fe2+) ions. The brookite TiO2 nanorod with site-selective modification of Fe3+ ions showed much higher photocatalytic activity than that of commercial brookite TiO2 loaded with Fe ions under visible-light irradiation because of the separation of redox sites. In other words, oxidation and reduction proceed over Fe3+ ion-modified {2 1 2} faces of the TiO2 surface and on {2 1 0} faces of the TiO2 surface without modification of Fe3+, respectively

Boosting visible-light-driven photocatalytic performance of waxberry-like CeO<inf>2</inf> by samarium doping and silver QDs anchoring

In this work, waxberry-like CeO2 photocatalyst (denoted ASC) with prominent visible-light-driven photocatalytic performances for multi-model reactions was achieved by Sm doping and Ag quantum dots (QDs) anchoring. For instance, the as-fabricated ASC acquired 7.08-times and 6.83-times higher activities for CH3CHO removal and H2 production than those of pure CeO2 counterpart, respectively. The concentration of oxygen vacancies (Ov) in CeO2 is distinctly increased by Sm doping, resulting in a narrower bandgap of the Sm-doped CeO2 (SC). Under visible light irradiation, the Ov caused by doping can capture the photo-excited electrons and construct a doping-related transition state between the conduction band (CB) and the valence band (VB), which can effectively limit the recombination of photo-excited electrons and holes. These captured electrons further fleetly transfer to the co-catalytic sites of anchored Ag QDs, strengthening the absorption utilization for visible-light synchronously. The migration of charge carriers and proposed mechanisms were well elaborated by transient photovoltage (TPV), surface photovoltage (SPV) and density functional theory (DFT) calculation. It is hoped our work in this paper could provide potential and meaningful strategies for the design of noble metal quantum dots modified metal oxide semiconductors and facilitate their applications in other photocatalytic fields effectively

Detecting and pyramiding target QTL for plant- and grain-related traits via chromosomal segment substitution line of rice

IntroductionPlant height and grain length are important agronomic traits in rice, exhibiting a strong effect on plant architecture and grain quality of rice varieties.MethodsMethods: A novel rice chromosomal segment substitution line (CSSL), i.e., CSSL-Z1357, with significantly increased plant height (PH) and grain length (GL) was identified from CSSLs constructed by using Nipponbare as a receptor and a restorer line Xihui 18 as a donor. Seven agronomic traits of PH, PL, GL, GW, GPP, SPP, and TGW were phenotyped, and REML implemented in HPMIXED of SAS were used to detect the QTL for these traits. Secondary CSSLs were screened out via marker-assisted selection (MAS) to estimate the additive and epistatic effects of detected QTLs, evaluating the potential utilization of pyramiding the target QTLs for yield and quality improvement of rice varieties.Results and DiscussionResults and Discussion: CSSL-Z1357 carried nine segments from Xihui 18 with an average segment length of 4.13 Mb. The results show that the long grain of CSSL-Z1357 was caused by the increased number of surface cells and the length of the inner glume. Thirteen quantitative trait loci were identified via the F2 population of Nipponbare/CSSL-Z1357, including three each for GL (qGL-3, qGL-6, and qGL-7) and PH (qPH-1, qPH-7, and qPH-12I), among which qGL-3 increased GL by 0.23 mm with synergistic allele from CSSL-Z1357. Additionally, three single (S1 to S3), two double (D1, D2), and one triple segment (T1) substitution lines were developed in F3 via MAS. Results show that pyramiding the segments from Chr.3 (qGL-3 and qPH-3), Chr.6 (qGL-6 and qPH-6), and Chr.7 (Null and qPH-7) tended to result in better phenotype of increased GL and PH and decreased grain width, providing a potential basis for enhancing grain yield and quality in rice breeding

Systems Biology Analysis of the Effect and Mechanism of Qi-Jing-Sheng-Bai Granule on Leucopenia in Mice

Qi-Jing-Sheng-Bai granule (QJSB) is a newly developed traditional Chinese medicine (TCM) formula. Clinically, it has been used for the treatment of leucopenia. However, its pharmacological mechanism needs more investigation. In this study, we firstly tested the effects of QJSB on leucopenia using mice induced by cyclophosphamide. Our results suggested that QJSB significantly raised the number of peripheral white blood cells, platelets and nucleated bone marrow cells. Additionally, it markedly enhanced the cell viability and promoted the colony formation of bone marrow mononuclear cells. Furthermore, it reversed the serum cytokines IL-6 and G-CSF disorders. Then, using transcriptomics datasets and metabonomic datasets, we integrated transcriptomics-based network pharmacology and metabolomics technologies to investigate the mechanism of action of QJSB. We found that QJSB regulated a series of biological processes such as hematopoietic cell lineage, homeostasis of number of cells, lymphocyte differentiation, metabolic processes (including lipid, amino acid, and nucleotide metabolism), B cell receptor signaling pathway, T cell activation and NOD-like receptor signaling pathway. In a summary, QJSB has protective effects to leucopenia in mice probably through accelerating cell proliferation and differentiation, regulating metabolism response pathways and modulating immunologic function at a system level