Search

Utilizing renewable energy such as offshore wind power to electrolyze seawater for hydrogen production offers a sustainable development pathway to address energy and climate change issues. In this study, by incorporating nitrogen-doped carbon quantum dots (N-CDs) into precursors, we successfully synthesized a nitrogen-doped carbon (NC)-layer-coated Co(OH)F/CoP2 catalyst NC@Co(OH)F/CoP2/NF loaded on nickel foam (NF). The introduction of N-CDs induced significant morphology change of the catalyst, facilitating the exposure of numerous active sites, ensuring the presence of catalytically active species CoP2 in nanoparticle form and avoiding agglomeration, which was advantageous to enhancing the overall hydrogen evolution reaction (HER) activity of the catalyst. The formation of Co–N bonds accelerated electron transfer, regulated the electronic structure, and optimized the catalyst's adsorption capacity for H* intermediates, which resulted in remarkably improved HER performance. In addition, Co(OH)F can also serve as a structural support, preventing the catalyst from collapsing during the HER catalytic process. NC@Co(OH)F/CoP2/NF exhibited excellent HER activity in alkaline freshwater and alkaline seawater, respectively requiring overpotentials of only 107 and 128 mV to achieve a current density of 100 mA cm−2. More importantly, it also demonstrated excellent HER activity at high current densities, with overpotentials of 189 and 237 mV at a current density of 1000 mA cm−2 in alkaline freshwater and alkaline seawater, respectively. This work provides new insights into the design and construction of highly efficient HER catalysts for applications in alkaline freshwater and seawater. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction to ammonia (ENO3RR) has attracted great attention owing to its characteristics of treating wastewater while producing high value-added ammonia. In this study, we successfully prepared a heterojunction electrocatalyst Fe2O3/ZnO consisting of Fe2O3 nanosheets and ZnO nanoparticles, where the construction of the Fe2O3/ZnO heterojunction not only increased the exposure of the active sites of the catalyst, accelerated the interfacial electron transfer, and improved the conductivity of the catalyst but also optimized its overall electronic structure. Thus, Fe2O3/ZnO demonstrated a high Faraday efficiency of 97.4% and an ammonia yield of 6327.2 μg h−1 cm−2 at −1.0 V (vs. RHE) in 0.1 M KNO3 and 0.1 M PBS. DFT calculations also confirmed that the constructed Fe2O3/ZnO heterojunction effectively decreased the reaction energy barrier of *NO → *NHO and accelerated the reaction kinetics, which is favourable for ENO3RR. This study provides a new and facile design strategy of catalysts for electrochemical nitrate reduction to ammonia. [ABSTRACT FROM AUTHOR]

A CuO/Mn2O3 heterojunction catalyst is successfully prepared by a simple hydrothermal and calcination method, which exhibits a unique spindle-like morphology with a rough surface that can expose more active sites. Moreover, the formation of a heterogeneous interface accelerates the interfacial electron transfer, and optimizes the desorption and hydrogenation process of CuO/Mn2O3 to intermediates, significantly enhancing the NO3RR activity. Thus, CuO/Mn2O3 exhibits a high NH3 Faradaic efficiency of 98.44%, and a high NH3 yield of 12 990.49 μg h−1 cm−2 at −0.7 V vs. RHE in alkaline medium. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction reaction (ENO3RR) is a green ammonia synthesis method under ambient conditions relative to the traditional Haber–Bosch technology, which does not require high-temperature or high-pressure conditions and can convert nitrate pollutants in the environment into value-added NH3, thus achieving a dual purpose. However, more electrocatalysts with a remarkable performance towards high-efficiency ENO3RR need to be developed. In this work, a Cu/NiO-NF composite electrocatalyst with a nanorod structure on nickel foam was successfully fabricated, which contains heterogeneous interfaces between Cu and NiO toward selective electrocatalytic nitrate reduction for ammonia synthesis. The steric nanorod morphology of the catalyst can significantly increase the surface area, expose more active sites, and improve the reaction activity. Moreover, the construction of the composite and the interface effectively boosts the synergistic effect of the active species Cu and NiO, which can regulate the electronic structure of the catalyst, expose more active sites, enhance the conductivity of the material, and accelerate the interfacial electron transfer, thereby further promoting the ENO3RR performance. This Cu/NiO-NF composite exhibits a high NH3 yield of 0.6 mmol h−1 cm−2 and up to 97.81% faradaic efficiency at the optimal applied potential of −1.0 V (vs. RHE) in a concentration of 0.1 M NO3−-containing 0.1 M PBS. Furthermore, it demonstrates excellent electrochemical cycle stability. This work provides insights into the rational design and fabrication of ENO3RR electrocatalysts for potential electrocatalytic applications. [ABSTRACT FROM AUTHOR]

Highlights: Inspired by the photoreception mechanisms of urchins, the urchin-like Ti3C2Tx@ZnO hollow spheres are rationally designed as high-performance microwave absorbents by constructing ZnO nanoarrays onto the surface of Ti3C2Tx hollow spheres. Both experimental and theoretical simulation results demonstrate that the microstructure of urchin-like possesses giant advantages in electromagnetic wave absorption performance, which is superior to most absorbers with similar components. Ingenious microstructure design and rational composition selection are effective approaches to realize high-performance microwave absorbers, and the advancement of biomimetic manufacturing provides a new strategy. In nature, urchins are the animals without eyes but can "see", because their special structure composed of regular spines and spherical photosensitive bodies "amplifies" the light-receiving ability. Herein, inspired by the above phenomenon, the biomimetic urchin-like Ti3C2Tx@ZnO hollow microspheres are rationally designed and fabricated, in which ZnO nanoarrays (length: ~ 2.3 μm, diameter: ~ 100 nm) as the urchin spines are evenly grafted onto the surface of the Ti3C2Tx hollow spheres (diameter: ~ 4.2 μm) as the urchin spherical photosensitive bodies. The construction of gradient impedance and hierarchical heterostructures enhance the attenuation of incident electromagnetic waves. And the EMW loss behavior is further revealed by limited integral simulation calculations, which fully highlights the advantages of the urchin-like architecture. As a result, the Ti3C2Tx@ZnO hollow spheres deliver a strong reflection loss of − 57.4 dB and broad effective absorption bandwidth of 6.56 GHz, superior to similar absorbents. This work provides a new biomimetic strategy for the design and manufacturing of advanced microwave absorbers. [ABSTRACT FROM AUTHOR]

Nowadays, there is an urgent need for microwave absorbing materials with light weight, thin thickness, and strong absorbing ability to solve the problem of electromagnetic radiation. In this study, we report a novel high-performance aerogel absorber by growing MoO 3 -doped WO 3 nanoflakes on reduced graphene oxide (rGO) sheets. The resultant rGO-Mo-WO 3 aerogel displays a low density (∼75 mg/cm3) and unique hierarchical architectures including 3D porous microstructures, 2D rGO skeleton, and binary transition metal oxide of Mo-WO 3 nanoflakes, thus leading to excellent microwave absorption performances. Typically, rGO-Mo-WO 3 aerogel exhibits an ultra-strong reflection loss (RL) of −61.8 dB with a thin coating thickness of 1.54 mm. And a wide effective absorption bandwidth of 6.24 GHz can be achieved at a low filler loading of 8 wt%, much superior to previous ones. The synergistic effect of moderate polarization relaxation loss and weak conduction loss together with the porous microstructure for the aerogel result in the suitable impedance matching and strong microwave attenuation ability. This work may demonstrate a promising method to fabricate hierarchically nanostructured absorbers with the advantages of light weight, ultra-strong microwave absorption, and thin coating thickness. [Display omitted] • A functional aerogel is fabricated by growing MoO 3 -doped WO 3 nanoflakes on rGO sheets. • The aerogel with low density and unique hierarchical architectures displays excellent microwave absorption. • An ultra-strong reflection loss of −61.8 dB is achieved at a thin thickness of 1.54 mm. • A wide effective absorption bandwidth of 6.24 GHz is achieved at an ultra-low filler loading of 8 wt%. • The microwave absorption mechanism of the aerogel is proposed in detail. [ABSTRACT FROM AUTHOR]

A novel 3D Eu(III) metal–organic framework (Eu-MOF-1) formulated as [Eu(L)(H2O)(DMA)] (L = 2-(2-nitro-4-carboxylphenyl)terephthalic acid) has been successfully synthesized under solvothermal conditions and characterized by structural analyses. Eu-MOF-1 displays a new 3D framework containing EuIII ions, ligand L, and coordinated DMA molecules and water molecules. The fluorescence investigations indicate that Eu-MOF-1 emits bright red luminescence, and shows relatively high water stability and outstanding chemical stability under a relatively wide range of pH conditions. It is noteworthy that Eu-MOF-1 can quantitatively detect p-aminophenol (PAP) which is a metabolite of phenylamine in human urine. More significantly, Eu-MOF-1 is the first reported multi-responsive luminescent sensor for detecting the biomarker PAP, and MnVII and CrVI anions with high selectivity, sensitivity, recyclability and relatively low detection limits in aqueous solutions. Furthermore, the possible sensing mechanisms of Eu-MOF-1 for selective sensing have also been explored in detail. Eu-MOF-1 could be an ideal candidate as a multi-responsive luminescent sensor in biological and environmental areas. [ABSTRACT FROM AUTHOR]

Three novel Cd(II)/Zn(II) coordination polymers (CPs), namely [Cd(L)(BPDC)0.5H2O]·0.5H2O (1), [Zn2(L)2(BPDC)]·2H2O (2) and [Cd2(L)(BTC)H2O]·3H2O (3) (L = 4-(tetrazol-5-yl)phenyl-4,2′:6′,4′′-terpyridine, H2BPDC = 4,4′-biphenyldicarboxylic acid, and H3BTC = 1,3,5-benzenetricarboxylic acid), have been successfully synthesized and characterized. CP 1 and CP 2 display new two-dimensional double-layered honeycomb frameworks containing uncoordinated nitrogen atoms from pyridine and tetrazole rings, which can easily form hydrogen bonds with various analytes. CP 3 exhibits a 3D framework also with uncoordinated nitrogen atoms from pyridine and tetrazole rings. The fluorescence explorations indicate that CPs 1–3 exhibit strong blue luminescence and excellent chemical stability under a relatively wide range of pH conditions. It is worth noting that CPs 1–3 can quantitatively detect hippuric acid (HA), which is a metabolite of toluene in human urine, with high selectivity, sensitivity, fast response and relatively low detection limits. Moreover, the sensing mechanism of CPs 1–3 for HA can mainly be ascribed to fluorescence resonance energy transfer (FRET). CPs 1–3 could be ideal candidates as HA sensors in human urine samples for practical applications. Notably, to the best of our knowledge, we report for the first time Cd(II)/Zn(II)-based luminescent sensors for detecting HA in simulated urine. [ABSTRACT FROM AUTHOR]