Sheet-like Architectures Research Articles

Phosphate-modified cobalt silicate hydroxide with improved oxygen evolution reaction

Oxygen Evolution Reaction (OER) has gained significant attention due to its crucial role in renewable energy systems. The quest for efficient and low-cost OER catalysts remains a challenge of significant interest and importance. In this work, phosphate-incorporated cobalt silicate hydroxide (denoted as CoSi-P) is reported as a potential electrocatalyst for OER. The researchers first synthesized hollow spheres of cobalt silicate hydroxide Co3(Si2O5)2(OH)2 (denoted as CoSi) using SiO2 spheres as a template through a facile hydrothermal method. Phosphate (PO43−) was then introduced to layered CoSi, leading to the reconstruction of the hollow spheres into sheet-like architectures. As expected, the resulting CoSi-P electrocatalyst demonstrated low overpotential (309 mV at 10 mA·cm−2), large electrochemical active surface area (ECSA), and low Tafel slope. These parameters outperform CoSi hollow spheres and cobaltous phosphate (denoted as CoPO). Moreover, the catalytic performance achieved at 10 mA cm−2 is comparable or even better than that of most transition metal silicates/oxides/hydroxides. The findings indicate that the incorporation of phosphate into the structure of CoSi can enhance its OER performance. This study not only provides a non-noble metal catalyst CoSi-P but also demonstrates that the incorporation of phosphates into transition metal silicates (TMSs) offers a promising strategy for the design of robust, high-efficiency, and low-cost OER catalysts.

Cage versus sheet: Probing the Determinants of Protein – Cucurbit[7]uril Crystalline Architectures

The donut-shaped cucurbit[n]urils (Qn) are a class of rigid macrocyclic receptor with protein recognition capabilities. Qn encapsulation of amino acid side chains can enable protein assembly. Recently, cucurbit[7]uril (Q7) has been applied as a molecular glue for organizing protein building blocks into crystalline architectures. Q7 co-crystallization with dimethylated Ralstonia solanacearum lectin (RSL*) has yielded novel crystalline architectures. Co-crystallization of RSL* and Q7 yields either cage- or sheet-like architectures which may be modulated via protein engineering. However, questions remain as to the factors dictating the formation of one architecture over another (cage versus sheet). Here, we make use of an engineered RSL*-Q7 system which co-crystallizes as the cage or sheet assembly with easily-distinguished crystal morphologies. Using this model system, we probe how the crystallization conditions dictate which crystalline architecture is adopted. Protein-ligand ratios and the sodium concentration were identified as key determinants for the growth of the cage versus sheet assemblies.

Construction of graphene oxide wrapped gadolinium vanadate nanocomposites as an efficient electrocatalyst for the amperometric sensing of sulfadiazine

Ultrasensitive detection of antibiotic molecules is fast becoming a vital field of research in recent years. In this research article, we hydrothermally developed a pellet-shaped nanomaterial based on rare-earth metal vanadate (GdVO4) and they are made of composites with graphene oxide (GO). The surface morphology studies through microscopes confirm the effective formation of pellet and sheet-like architectures of GdVO4 and GO. The synthesized nanocomposites are probed for the electrochemical detection of antibiotic sulfadiazine (SLZ). The electrochemical detection performance is investigated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and i-t amperometry analysis. The primary composite of GdVO4 @GO displayed superior selectivity and sensitivity to GdVO4 and GO. Through i-t amperometry analysis, enhanced sensitivity of 1.3009 µA µM−1 cm−2 and a limit of detection of 3.1 nM for SLZ detection are achieved. In order to validate the fabricated SLZ sensor, we tested them in real-world biological and environmental samples like human blood serum, river and waste water samples. The GdVO4 @GO-based sensor performed remarkably well with good selectivity for SLZ.

Lattice engineering route for self-assembled nanohybrids of 2D layered double hydroxide with 0D isopolyoxovanadate: chemiresistive SO2 sensor

Tuning the interior chemical composition of layered double hydroxides (LDHs) via lattice engineering route is a unique approach to enable multifunctional applications of LDHs. In this regard, the exfoliated 2D LDH nanosheets coupled with various guest species lead to the lattice-engineered LDH-based multifunctional self-assembly with precisely tuned chemical composition. This article reports the synthesis and characterization of mesoporous zinc–chromium-LDH (ZC-LDH) hybridized with isopolyoxovanadate nanohybrids (ZCiV) via lattice-engineered self-assembly between delaminated ZC-LDH nanosheets and isopolyoxovanadate (iPOV) anions. Electrostatic self-assembly between 2D ZC-LDH monolayers and 0D iPOV significantly altered structural, morphological, and surface properties of ZC-LDH. The structural and morphological study demonstrated the formation of mesoporous interconnected sheet-like architectures composed of restacked ZCiV nanosheets with expanded surface area and interlayer spacing. In addition, the ZCiV nanohybrid resistive elements were used as a room-temperature gas sensor. The selectivity of ZCiV nanohybrid was tested for various oxidizing (SO2, Cl2, and NO2) gases and reducing (LPG, CO, H2, H2S, and NH3) gases. The optimized ZCiV nanohybrid demonstrated highly selective SO2 detection with the maximum SO2 response (72%), the fast response time (20 s), low detection limit (0.1 ppm), and long-term stability at room temperature (27 ± 2 °C). Of prime importance, ZCiV nanohybrids exhibited moderately affected SO2 sensing responses with high relative humidity conditions (80%–95%). The outstanding SO2 sensing performance of ZCiV is attributed to the active surface gas adsorptive sites via plenty of mesopores induced by a unique lattice-engineered interconnected sheet-like microstructure and expanded interlayer spacing.

Oxygen defects-induced charge transfer in Bi7O9I3 for enhancing oxygen activation and visible-light degradation of BPA

Two-dimensional (2D) bismuth-based semiconductors have aroused intensive concern owing to their prominent photocatalytic activity for organic pollutants removal. In this work, a facile strategy for introducing oxygen vacancy in Bi-based oxyiodides (BixOyIz) sheet-like architectures to activate molecular oxygen was proposed. The structure, photoelectric properties and visible light (λ > 420 nm) induced photocatalytic activities of these samples for decomposition of bisphenol A (BPA) were systematically characterized and evaluated. The as-prepared Bi7O9I3 with a feeding Bi/I molar ratio of 1:1 exhibited the best photocatalytic activity comparable to those of similarly synthesized Bi7O9I3 with other molar ratios and BiOIO3 catalysts. The optimal Bi7O9I3 achieved excellent photocatalytic activity with 99.6 % degradation efficiency of BPA within 20 min and superior structural stability with 95.1 % degradation retention over 5 cycling tests. In addition, the resulting Bi7O9I3 sample displayed a high mineralization efficiency of BPA. Importantly, the plenty of oxygen vacancies (Vos) exsiting in Bi7O9I3 played the dominant role in both accelerating electron transfer and activating molecular oxygen to facilitate the generation of superoxide radical (O2·-) and singlet oxygen (1O2), thereby proceeding oxidative degradation of BPA molecules during photoreactions. The efforts and attempts are also extendable to synthesis other 2D photocatalysts, providing potential for effective charge-carrier separation and molecular oxygen activation.

CoNi/MoC nanoparticles entrapped into N, P-codoped carbon nanotubes-on-nanosheets: A synergy of 1D@2D heterostructures with multiple active sites for rechargeable Zn-air battery

Researches of bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial in development of liquid metal-air batteries. Herein, a simple one-step method is developed for carbonizing the metal precursors and dicyandiamide to prepare CoNi/MoC nanoparticles incorporated into N, P-codoped carbon nanotubes-on-nanosheets (CoNi/MoC-NP-CTS). Benefiting from the unique sheet-like architectures with regular nanotubes and the synergistic effect of multi-components, the resultant CoNi/MoC-NP-CTS shows the positive half-wave potential of 0.89 V (vs. RHE) and small Tafel slope of 51.1 mV dec−1 for ORR, coupled by the enhanced OER performance with an overpotential of 335 mV at 10 mA cm−2. More notably, the CoNi/MoC-NP-CTS-based Zn-air battery exhibits largely higher power density (132 mW cm−2) than commercial Pt/C + RuO2-based battery (80 mW cm−2), together with the outstanding cycling durability (480 cycles, 160 h). This work opens a new avenue to design and construct advanced non-precious-metal electrocatalysts in metal-air batteries.

Xp11 neoplasma with melanocytic differentiation: a clinicopathological analysis

Objective: To investigate the clinical, histologic and immunophenotypic features, genetic alterations and prognosis of the rare Xp11 neoplasm with melanocytic differentiation. Methods: Twenty-one cases were selected from the Department of Pathology, Jingling Hospital, Nanjing University School of Medicine from May 2008 to May 2018. The clinicopathologic, immunohistochemical, molecular analysis and follow-up details were collected. Results: There were 7 males and 14 females, with their ages ranging from 4 to 57 years (mean 32.8 years). The tumors were located in kidney (11 cases), pelvis (three cases), and in pancreas, retroperitoneum, adrenal gland, small intestine, prostate, cervix and appendix (one case each). Microscopically, most tumors shared similar morphology such as purely nested or sheet-like architectures separated by a delicate vascular network, purely epithelioid cells with clear to granular eosinophilic cytoplasm, lacks of papillary structures, spindle cell or fat components, uniform round to oval nuclei with small visible nucleoli, and in most of them (16/21) melanin pigment. Immunohistochemically, all cases showed moderately (2+) or strongly (3+) positive staining for TFE3 and Cathepsin K. HMB45 and Melan A were focally expressed in three of 21 cases, while the remaining cases showed typically moderate(2+) or strong (3+) expression. None of the cases were immunoreactive for SMA, desmin, CKpan, S-100 and PAX8. All cases showed TFE3 rearrangement using fluorescence in-situ hybridization (FISH). Fusion FISH assays detected SFPQ-TFE3 gene fusion in 16 cases, NONO-TFE3 gene fusion in two, ASPL-TFE3 and MED15-TFE3 gene fusions in one case each. Polymerase chain reaction and direct sequencing detected SFPQ-TFE3 gene fusion in nine cases, NONO-TFE3 and MED15-TFE3 gene fusions in one case each. Clinical follow-up was available for 15 patients for 12 to 74 months. Six patients died of the disease; and three had recurrences and/or metastases. Six patients were alive with no evidence of disease after initial resection. Conclusions: Xp11 neoplasm with melanocytic differentiation has unique morphologic, immunophenotypic and genetic characteristics. The tumor is aggressive, and should be differentiated from Xp11 translocation RCC and perivascular epithelioid cell tumor.

Self-assembly of nickel phosphate-based nanotubes into two-dimensional crumpled sheet-like architectures for high-performance asymmetric supercapacitors

This work demonstrates the successful self-assembly of amorphous nickel phosphate-based nanotubes into two-dimensional (2D) crumpled sheet-like architectures for the first time by employing nickel glycerate particles as sacrificial templates through a two-step phosphoric acid-assisted solvothermal method. A “self-deconstruction-self-weaving” mechanism is believed to be responsible for the formation of such nanotube-assembled crumpled sheet-like architectures from the nickel glycerate template. The asymmetric supercapacitor (ASC) device assembled using nanotube-assembled amorphous 2D nickel phosphate (NiHPi-500) as the positive electrode and activated carbon (AC) as the negative electrode exhibits high energy densities of 50 W h kg-1, 40 W h kg-1, and 32 W h kg-1 at power densities of 362 W kg-1, 1443 W kg-1, and 2838 W kg-1, respectively. Furthermore, this ASC device can retain an impressive energy density of 18 W h kg-1 at high power density of 7242 W kg-1. In addition, the NiHPi-500//AC ASC also displays good long-term stability with a high capacitance retention of 100% after 5000 cycles at a high current density of 10 A g-1. The excellent electrochemical performance is attributed to the unique nanotube-assembled 2D architectures, the good interconnectivity between the nanotubes, and the large surface area arising from such structures which can provide many active sites for the redox reactions and facility effective transport and diffusion of the electrolyte ions, leading to more efficient utilization of the active material. These results indicate the promising potential of nanotube-assembled 2D nickel phosphate nanoarchitectures for supercapacitor applications.

Facile one-step hydrothermal synthesis and luminescence properties of Eu3+-doped NaGd(WO4)2 nanophosphors

Eu3+-doped NaGd(WO4)2 nanophosphors were synthesized via a facile one-step hydrothermal method without any surfactants or a further heat treatment. X-ray powder diffraction (XRD), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), the photoluminescence (PL) excitation and emission spectra, and decay curves were used to characterize NaGd(WO4)2:Eu3+ phosphors. The results show that the Eu3+-concentration has little influence on the structure and morphology of the as-synthesized samples. However, pH value plays a vital role on the structure and morphology of NaGd(WO4)2. The well-crystallized sheet-like NaGd(WO4)2 phosphors can be obtained only at pH = 5–7. On the basis of the time-dependent synthesis, a possible growth mechanism of sheet-like architectures is proposed. The luminescence properties of NaGd1-xEux(WO4)2 (0 ≤ x ≤ 1) are investigated. It is found that the charge transfer band of Eu3+ shifts to lower energy and broadens with increasing the Eu3+-concentration.

Layered 2D Sheetlike Supramolecular Polymers Formed by O–H···Anion Hydrogen Bonds

A hexahydroxyterphenyl was prepared in two steps and 77% overall yield. Co-crystallization of this ligand with a range of tetrabutylammonium salts gave [2 + 2] supramolecular macrocycles assembled through O–H···anion hydrogen bonds. These macrocycles form 2D sheetlike architectures through intermolecular hydrogen bonds between phenol groups. Bulk samples of these structures were prepared in high yields (70–100%) and were characterized by X-ray crystallography, 1H NMR spectroscopy, IR spectroscopy, and elemental analysis. The relatively predictable organization of these molecules in the solid state may be exploited for crystal engineering.

Depositional processes across the Sinú Accretionary Prism, offshore Colombia

The Pliocene to Recent of the Sinú Accretionary Prism, offshore Colombia, features gravity current dominated basins characterised primarily by channel- and sheet-like architectures and those with dominantly hemipelagic fills. The prism is fed by rivers that drain from uplifted older basins and volcanic Andean terranes to the south and east which source large volumes of sediment to the Colombian Shelf into the Colombian Basin. Some basin fills show evidence of both localised fold-induced sediment failure and regional-scale shelf collapse, both related to the generation and destruction of oversteepened slopes. Large scale collapses can create new sediment routing pathways and/or local depocentres into which sediment subsequently accumulates. In the Colombian Basin, even relatively distal basins show evidence of channel activity related primarily to the creation of new sediment distribution pathways through breaches in the substrate barriers between basins. These channels are often orientated parallel to the regional drainage trend, suggesting that regional sediment transport trends can assert themselves relatively early in a basin filling history regardless of the local bathymetric grain. While, at a regional scale, sediment dispersal fairways reflect drainage from the continental shelf to the basin floor, intraslope basins form local bathymetric obstructions that can drive local spatial variations in sediment distribution. Thus, both local and regional length scales of bathymetric control are evident within the intraslope basins of the Sinú Accretionary Prism. Although regional dispersal patterns generally become more important in time, individual intraslope basins exhibit more complex filling histories because events such as sill or shelf collapse may serve to disrupt established distribution pathways, initiating repeated episodes of adjustment.