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Development of highly active and selective electrocatalysts for the reduction of nitrate (NO3–) to ammonia is critical for the production of green ammonia. Herein, we designed and synthesized NiMoO4 nanocubes as an efficient electrocatalyst for nitrate reduction using deep eutectic solvents (DESs) as synthesis media. By constructing Mo and Ni dual-active sites, Mo facilitates NO3– adsorption/association, and Ni acts as an active hydrogen (*H) donating center. The amount and destination of *H can be regulated, which can effectively enhance the activity of the NO3– reduction to NH3 reaction (NO3–RR). The optimized sample possessed excellent NO3–RR activity. An NH3–N selectivity of up to 96.94% and a Faraday efficiency of up to 96.13% can be achieved at −0.4 V in a neutral solution. The catalytic NO3–RR mechanism was also investigated by density functional theory (DFT) calculations. This dual-active site electrocatalyst provides an alternative idea for the synthesis and application of high-performance NO3–RR catalysts. [ABSTRACT FROM AUTHOR]

Designing approaches to synthesizing nanostructure photocatalysts is crucial to boosting applications in photocatalytic H2 production. Herein, a Z-scheme p–n heterojunction for photocatalytic H2 production was designed and constructed by decorating p-type CoP3 quantum dots on n-type CdZnS nanorods. The flower-like CoP3/CdZnS nanorod assembly benefits from light absorption and full contact with the solution. An internal electric field forms at the interface of the p–n junction, which provides a Z-scheme charge transport path for efficient migration and separation of photogenerated charges. In result, the hydrogen production rate of the CoP3/CdZnS p–n junction is 33 times that of CdZnS. The study provided a novel approach to the synthesis of self-assembled nanostructures of quantum dots on nanorod assemblies that have important applications in photocatalysis for energy conversion. [ABSTRACT FROM AUTHOR]

Developing a highly efficient catalyst for the oxygen evolution reaction (OER) is of great significance for its application in electrocatalytic water splitting. Herein, a solid–solid transformation strategy has been developed to construct sulfur-doped Ni0.5Co0.5Fe2O4 spinel porous single-crystal nanosheet arrays on nickel foam (S-NCFO/NF). The single-crystalline nanosheet self-assembled nanostructures can provide fast charge transfer channels. With the effect of S-doping, a distorted/incomplete octahedral structure nanosheet can be formed. The unique porous S-NCFO nanosheets can provide a large number of active sites and sufficiently contact the electrolyte to adsorb OH– and desorb O2. By virtue of the porous single-crystal nanosheet, sulfur-doped spinel structure, and the unique self-assembled nanosheet configurations, the S-NCFO/NF electrode exhibits enhanced OER performance with low overpotentials at 100 mA cm–2 of 300 mV in 1 M KOH and 317 mV in 1 M KOH + 0.5 M NaCl. The synthesis strategy provides insight for the preparation and application of self-assembled nanostructures in electrocatalytic seawater splitting. [ABSTRACT FROM AUTHOR]

Designing and developing low-cost, high-efficiency catalysts to reduce the overpotential and improve the efficiency of hydrogen energy conversion are current research hotspots. In this work, CoNi2S4 nanosheets on carbon cloth (CoNi2S4/CC) were prepared to use one-step pyrolysis of the deep eutectic solvent (DES) precursor. It is feasible to cover carbon cloth evenly with DES due to its intense adherence and liquid conditions at ambient temperature. The CoNi2S4 nanosheet's coupling a CC substrate increases the electron transport efficiency and prevents the catalyst from agglomeration and corrosion during catalytic processes. Self-supported CoNi2S4/CC exhibited excellent hydrogen evolution reaction (155 mV at 50 mA cm–2 and 30 mV at 10 mA cm–2) and oxygen evolution reaction (372 mV at 100 mA cm–2 and 153 mV at 10 mA cm–2) activities. Serving as a bifunctional catalyst, CoNi2S4/CC requires cell voltages of only 1.42 and 1.86 V to achieve 10 mA cm–2 and 100 mA cm–2 current density, respectively, in overall water splitting in 1.0 M KOH, exhibiting extraordinary durability. Moreover, CoNi2S4/CC exhibits excellent overall water-splitting activity in simulated seawater, which significantly advances the development of seawater electrolysis. [ABSTRACT FROM AUTHOR]

ZnO nanorod and nanoprism arrays have been directly synthesized on a large-area zinc substrate via a convenient solution method. The products were characterized with XRD, SEM, HRTEM, and photoluminescence (PL) spectroscopy. The influence of the solvent and the concentration of NaOH on the size and shapes of the as-prepared ZnO samples have been studied. It was found that ZnO nanorod or nanowire arrays were fabricated in alcohol, whereas ZnO nanoprisms with pyramid tips were produced in an alcohol−water mixture. The diameters of the nanorods or nanoprisms became thicker when a higher concentration of NaOH was used. Room-temperature PL spectra of the ZnO products showed a UV emission and a broad green band. The mechanism of the nanorods and nanoprisms in two systems is briefly discussed. [ABSTRACT FROM AUTHOR]

Oxygen vacancy (V o ) creation and morphology controlling make significant contributions to the electronic and structural regulation of metal oxide semiconductors, yet an investigation about convenient approaches for fabricating hierarchical catalyst with abundant oxygen vacancies still has significant challenges. Here, we report a unique method to create abundant oxygen vacancies in hierarchical Ag/TiO 2 nanoflowers during photocatalytic reaction, which is accompanied by light absorption variation and surface plasmon resonance (SPR) enhancement. Its high efficiency of photocatalytic H 2 evolution (the highest apparent quantum yield reaches 3.2% at 365 nm) and rhodamine B degradation can be considered as benefits from the synergistic effects of the well-arranged hierarchical structure, the photogenerated oxygen vacancies, and the SPR of cocatalyst Ag. This work proposes an effective strategy to optimize the synthesis of regular hierarchical structures and enriches the research on the vital function of oxygen vacancies in photocatalytic reactions., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Hyaluronidase (HAase) is becoming a new type of tumor marker since it has been demonstrated to be overexpressed in various kinds of cancer cells. In this study, we described a novel fluorescence method for sensitive, rapid, and convenient HAase detection and tumor-targeting drug delivery and imaging, using a probe prepared by electrostatic assembly of a cationic conjugated polymer (CCP) and anionic hyaluronan (HA) conjugated with the anticancer drug doxorubicin (Dox). The CCP we used was poly{[9,9-bis(6'-(N,N,N-diethylmethylammonium)hexyl)-2,7-fluorenylene ethynylene]-alt-co-[2,5-bis(3'-(N,N,N-diethylmethylammonium)-1'-oxapropyl)-1,4-phenylene]} tetraiodide (PFEP). HA is a natural mucopolysaccharide that can be hydrolyzed by HAase into fragments with low molecular weights. In the PFEP/HA-Dox complex, the fluorescence of PFEP was efficiently quenched due to electron transfer from PFEP to Dox. After the PFEP/HA-Dox complex was exposed to HAase or was taken up by cancer cells through the specific binding between HA and CD44 receptor, HA was degraded by HAase to release the Dox, leading to the recovery of PFEP fluorescence to the "turn-on" state. Moreover, the degree of fluorescence recovery was quantitatively correlated with the concentrations of HAase. Compared with many previously reported methods, our work did not require laborious multiple modifications of HA that may affect the activity of HAase. This point, combined with the excellent optoelectronic property of conjugated polymer, endowed this method with high sensitivity (detection limit: 0.075 U/mL), high specificity, and rapid response, making it applicable for reliable and routine detection of HAase. This fluorescent probe was successfully utilized to detect HAase levels in human urine samples; furthermore, it can also be employed as a multifunctional system by realizing tumor-targeting drug delivery and cell imaging simultaneously. The development of this fluorescence method showed promising potential for early tumor diagnosis and therapy based on HAase detection.

Simple, rapid, and sensitive detection of CD44 is of paramount importance since it plays pivotal roles in tumor initiation, growth and metastasis. Herein, we describe a novel method for sensitive, visual and facile fluorescence detection of CD44 and CD44-mediated cancer cell imaging, using a probe based on cationic conjugated polymer (CCP)-PFEP and fluoresceinamine-hyaluronan (FA-HA). HA is an anionic natural glycosaminoglycan that can specifically bind to the overexpressed CD44 on various kinds of cancer cells. PFEP and FA-HA formed a complex through electronic interactions, resulting in a highly efficient fluorescence resonance energy transfer (FRET) from PFEP to FA-HA; moreover, the efficiencies of FRET correlated with the concentrations of CD44 because the specific binding of HA-CD44 would separate FA-HA away from PFEP. This method did not require laborious and expensive dual-labeling or protein-labeling needed in previously reported detection methods of CD44. Just mix the sample and test solution containing the PFEP/FA-HA complex, and the results allowed naked-eye detection by observing fluorescent color of solutions with the assistance of a UV lamp. Most importantly, the use of a conjugated polymer with excellent amplification property as well as the specific binding of HA-CD44 endowed this method with high sensitivity and specificity, making it applicable for reliable quantitative detection of CD44. Furthermore, the PFEP/FA-HA complex formed nanoparticles in aqueous solution, and the nanoparticles can be selectively taken up by MCF-7 cells (cancer cell) through the HA-CD44 interaction, thereby giving rise to a dual-color tumor-targeted imaging probe with good photostability. The development of this fluorescent probe showed promising potential to make a reliable and routine method available for early diagnosis of cancer.

Hollow spheres and thin films of Ni(OH)(2) and NiO with unusual form and hierarchical structures have been synthesized by a simple solution chemistry method. First, in situ formed Ni(OH)(2) nanoflakelets organized on the surface of styrene-acrylic acid copolymer (PSA) latex particles to form core/shell structures. Ni(OH)(2) hollow shells built up with nanoflakelets were obtained after subsequent removal of the core latex particles by dissolving PSA latex in toluene; the removal of the cores by calcinations would result in NiO hollow shells, also with hierarchical structures. BET calculation showed the surface area of the NiO hollow spheres was 156 m(2)/g. The nanoflakelets could also organize themselves into thin films with hierarchical structures. It is anticipated that these novel structures will have some unique applications in Ni-based batteries and other potentials.