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The electrocatalytic urea oxidation reaction (UOR) provides a promising alternative pathway for oxygen evolution in water electrolysis due to its lower thermodynamic barriers. Developing efficient nonprecious metal UOR catalysts is important. Rational design of heterogeneous structures to regulate the morphology and electronic structure is an effective method to improve the activity of electrocatalysts. Herein, a unique heterostructure of ultrathin NiCo-LDH supported by FeNiCoS4 was constructed for the UOR via a facile hydrothermal followed by electrodeposition process. The electrode exhibits superior activity and stability in a solution of 1 M KOH containing 0.33 M urea, with a potential of 1.366 V at 50 mA cm−2 and excellent durability over 48 h. The outstanding performance is attributed to the high conductivity of FeNiCoS4, ultrathin NiCo-LDH and the strong interface interaction between the two components, regulating the local electronic structure of the active metals. This work represents an effective strategy for the preparation of an efficient UOR catalyst with promising applications. [ABSTRACT FROM AUTHOR]

Rechargeable potassium-ion batteries (PIBs) have shown great potential as an alternative to lithium-ion batteries (LIBs) owing to the abundant and available potassium reserves. However, their applications are hindered by unsatisfactory cycling stability of cathode materials. Herein, through electrochemical ion-exchange of the Na0.85Li0.12Ni0.22Mn0.66O2 compound, we reported P2-K0.56Na0.11Li0.12Ni0.22Mn0.66O2 (P2-KNaLNM) as a potential high-performance cathode for PIBs. The presence of Li plays a key role in suppressing the K+/vacancy ordering within transition metal slabs. Therefore, P2-KNaLNM underwent a simple single-phase reaction during intercalation/extraction of K+ ions. Consequently, P2-KNaLNM delivers a reversible capacity of 90.2 mA h g−1 and good capacity retention of 89.6% over 150 cycles at 0.2C between 1.5 and 4.6 V (vs. K+/K). Furthermore, a satisfactory capacity retention of 91.5% after 300 cycles is achieved at 0.5C because of the excellent K+ kinetics during the charge and discharge process. This work provides a feasible way to develop a promising cathode candidate for PIBs. [ABSTRACT FROM AUTHOR]

We report an innovative synthetic strategy for the generation of polysubstituted indoles from indolines, aryldiazonium salts, and azoles. The methodology encompasses an electrophilic substitution reaction affording C5-indoline intermediates which undergo an iodine-mediated oxidative transformation coupled with C–H functionalization to yield the indole derivatives. [ABSTRACT FROM AUTHOR]

We report a smart ion-exchange strategy to anchor molybdenum oxide particles on charge-modulated conjugated triazine frameworks (Mo/CTF-I) for electrochemically fixing nitrogen. The strong interaction between MoOx and CTF-I is conducive to the activation of the inert N2 molecule in the electro-chemical process. As a result, 5% Mo/CTF-I exhibited an excellent faradaic efficiency of 27.3% and an NH3 yield rate of 7.23 μg h−1 mgcat.−1 at −0.405 V vs. RHE in 0.1 M KOH, surpassing most previous reports. [ABSTRACT FROM AUTHOR]

Recently, blue-emitting phosphors have attracted great interest due to their application in full-spectrum white light illumination. In this paper, a novel blue-emitting MgAl2Si4O6N4:Eu2+ phosphor was successfully synthesized through the solid-state reaction method in a reducing atmosphere. Under the excitation of near-ultraviolet (n-UV) light, the MgAl2Si4O6N4:0.02Eu2+ phosphor effectively emits a broad blue emission band centered at 456 nm with the FWHM as large as 81 nm. With the increasing Eu2+ concentration, the emission bands of MgAl2Si4O6N4:Eu2+ shift to a shorter wavelength and the FWHMs broaden gradually. Moreover, the MgAl2Si4O6N4:0.02Eu2+ phosphor exhibits a slight thermal quenching at a higher temperature. After fabricating the as-prepared MgAl2Si4O6N4:0.02Eu2+ phosphor into a white LED device, the intense neutral white light emission is obtained with excellent CRI (87.4) and CCT (5645 K). These results suggest that the blue MgAl2Si4O6N4:Eu2+ phosphor is a promising candidate in n-UV excited white LEDs. [ABSTRACT FROM AUTHOR]

Recently, blue-emitting phosphors have attracted great interest due to their application in full-spectrum white light illumination. In this paper, a novel blue-emitting MgAl 2 Si 4 O 6 N 4 :Eu 2+ phosphor was successfully synthesized through the solid-state reaction method in a reducing atmosphere. Under the excitation of near-ultraviolet (n-UV) light, the MgAl 2 Si 4 O 6 N 4 :0.02Eu 2+ phosphor effectively emits a broad blue emission band centered at 456 nm with the FWHM as large as 81 nm. With the increasing Eu 2+ concentration, the emission bands of MgAl 2 Si 4 O 6 N 4 :Eu 2+ shift to a shorter wavelength and the FWHMs broaden gradually. Moreover, the MgAl 2 Si 4 O 6 N 4 :0.02Eu 2+ phosphor exhibits a slight thermal quenching at a higher temperature. After fabricating the as-prepared MgAl 2 Si 4 O 6 N 4 :0.02Eu 2+ phosphor into a white LED device, the intense neutral white light emission is obtained with excellent CRI (87.4) and CCT (5645 K). These results suggest that the blue MgAl 2 Si 4 O 6 N 4 :Eu 2+ phosphor is a promising candidate in n-UV excited white LEDs.

Covalent organic frameworks (COFs) are crystalline and porous organic materials attractive for photocatalysis applications due to their structural versatility and tunable optical and electronic properties. The use of photocatalysts (PCs) for polymerizations enables the preparation of well-defined polymeric materials under mild reaction conditions. Herein, we report two porphyrin-based donor-acceptor COFs that are effective heterogeneous PCs for photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT). Using density functional theory (DFT) calculations, we designed porphyrin COFs with strong donor-acceptor characteristics and delocalized conduction bands. The COFs were effective PCs for PET-RAFT, successfully polymerizing a variety of monomers in both organic and aqueous media using visible light ( λ max from 460 to 635 nm) to produce polymers with tunable molecular weights (MWs), low molecular weight dispersity, and good chain-end fidelity. The heterogeneous COF PCs could also be reused for PET-RAFT polymerization at least 5 times without losing photocatalytic performance. This work demonstrates porphyrin-based COFs that are effective catalysts for photo-RDRP and establishes design principles for the development of highly active COF PCs for a variety of applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)