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Transition metal selenides have garnered considerable attention in the field of electrocatalytic oxygen evolution reaction (OER). However, their OER performances still lag behind those of Ir-based materials due to limited exposed active sites, inefficient electron transfer and inadequate stability. In this study, we have successfully synthesized nitrogen-doped NiSe2 nanosheets, which exhibit high efficiency and long-term stability for the OER, requiring only 320 mV to reach a current density of 10 mA cm−2. The nitrogen doping plays a crucial role in effectively regulating the work function and semiconductor characteristics of NiSe2, which facilitates the electron transport and optimizes the catalytic sites. Furthermore, the NiSe2 nanosheets present a larger surface area with more exposed active sites, thus resulting in exceptional OER catalytic activity. The nitrogen-doped NiSe2 nanosheets also display superior stability, maintaining a sustained current density throughout an 8-h OER operation. [ABSTRACT FROM AUTHOR]

Benefitting from the capability of recording scalar (J) couplings and bonding information, 2D J-resolved NMR spectroscopy constitutes an important tool for molecular structure analysis and mixture component identification. Unfortunately, conventional 2D J-resolved experiments generally encounter challenges of insufficient spectral resolution and strong coupling artifacts. In this study, a general NMR approach is exploited to record absorption-mode artifact-free 2D J-resolved spectra. This proposal adopts the advanced triple-spin-echo pure shift yielded by chirp excitation element to eliminate J coupling splittings and preserve chemical shifts along the F2 dimension, and it additionally utilizes the echo-train J acquisition to reveal the multiplet structure along the F1 dimension in accelerated experimental acquisition. Thus, it permits one to extract multiplet structure information from crowded spectral regions in one-shot experiments, with considerable resolution advantage resulting from completely decoupling F2 dimension and absorption-mode presentation, thus facilitating analysis on complex samples. More importantly, this method grants the superior performance on suppressing strong coupling artifacts, which have been affirmed by experiments on a series of chemical samples. As a consequence, this proposed method serves as a useful tool for J coupling measurements and multiplet structure analyses on complex samples that contain crowded NMR resonances and strong coupling spin systems, and it may exhibit broad application potentials in fields of physics, chemistry, and medical science, among others. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence (ECL) represents a widely explored technique to generate light, in which the emission intensity relies critically on the charge‐transfer reactions between electrogenerated radicals. Two types of charge‐transfer mechanisms have been postulated for ECL generation, but the manipulation and effective probing of these routes remain a fundamental challenge. Here, we demonstrate the design of quantum dot (QD) aerogels as novel ECL luminophores via a versatile water‐induced gelation strategy. The strong electronic coupling between adjacent QDs enables efficient charge transport within the aerogel network, leading to the generation of highly efficient ECL based on the selectively improved interparticle charge‐transfer route. This mechanism is further verified by designing CdSe‐CdTe mixed QD aerogels, where the two mechanistic routes are clearly decoupled for ECL generation. We anticipate our work will advance the fundamental understanding of ECL and prove useful for designing next‐generation QD‐based devices. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is considered as one of the major roadblocks for many renewable electrochemical energy technologies, such as water splitting, rechargeable metal‐air batteries. Thus the development of efficient and low‐cost OER electrocatalysts has achieved a lot of research and development attention. Aerogels, as featured by large surface area, high porosity, and self‐supportability, provide an excellent platform for the design of efficient electrocatalysts. This review summarizes the recent progress of the aerogel‐based design of catalysts in tackling the challenges in the field of OER electrocatalysis. The correlation between catalyst design strategy and catalytic performances is evaluated to provide a roadmap for the development of aerogel‐based OER electrocatalysts. Thereafter, the current state of our understanding of the application of the aerogel concept in OER electrocatalysis is provided, which could serve as a guide to the development of future aerogel electrocatalysts. [ABSTRACT FROM AUTHOR]

Developing highly effective and stable non‐precious bifunctional oxygen electrocatalysts is crucial and challenging. Herein, we report nano‐mediated straight bamboo‐shaped nitrogen‐doped carbon nanotubes modified with encapsulated NiCo2S4‐based nanoparticles (E‐NiCo2S4/SBS‐NCNTs) by electrodeposition and procedural calcination strategy, in which nitrogen‐doped carbon nanotubes with straight bamboo shape (SBS‐NCNTs) show more average diameter and encapsulated NiCo2S4‐based nanoparticles (E‐NiCo2S4) are coated by carbon, and what makes us even more excited is that they are evenly dispersed on SBS‐NCNTs surface, not just at the tip or inside. When applied for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), E‐NiCo2S4/SBS‐NCNTs show excellent catalytic activity, and onset potential (Eonset) in OER and ORR is only 1.52 V and 0.95 V (vs. RHE) in 0.1 M KOH, respectively. More importantly, the hybrids exhibit good methanol tolerance, with almost unchanged for ORR performance after adding 0.5 M methanol, and it has highly stability, the current density dropped by 22% after 7 h of reaction. The interaction of NiCo2S4 with the external carbon layer can greatly enhance the electrocatalytic activity toward the OER and it has a complete 4e– reaction process toward the ORR. The excellent electrocatalytic activity is mainly due to synergistic enhancement effect, in which SBS‐NCNTs with highly catalytic activity provide good conductivity, expose more active sites and promotes fast mass transfer; Carbon‐coated NiCo2S4‐based nanoparticles can improve the local work function of SBS‐NCNT through synergistic electronic interaction, promoting O2 adsorption, ensure rapid electron transport, and enable SBS‐NCNT to improve its electrocatalytic activity. Because of the weakness of Ostwald effect and synergistic enhancement, the stability and catalytic activity of NiCo2S4‐based nanoparticles can be greatly improved. All these advantages can synergistically improve the electrocatalytic efficiency and make it become one of the most promising bifunctional oxygen electrocatalysts. [ABSTRACT FROM AUTHOR]

New composite functional crystals of Tm3+:Ca3NbGa3Si2O14 (Tm3+:CNGS) were successfully grown by the Czochralski (CZ) method. The structural, thermal and spectral properties of Tm3+:CNGS crystals were investigated. The laser output of a Tm3+:CNGS crystal in the 2 μm band was studied for the first time. The results showed that Tm3+:CNGS achieved a maximum output of 740 mW at a pump power of 5 W, and the slope efficiency and light-to-light conversion efficiency reached 17.07% and 14%, respectively. The thermal properties are presented, and the coefficient of linear thermal expansion of Tm3+:CNGS increased with respect to that of a pure CNGS crystal in the Z-axis direction, which may have been due to a change in the bulk density of the oxygen dodecahedron in the X-axis direction after partial replacement of the rare earth ions. In addition, the specific heat, thermal diffusivity, and thermal conductivity of Tm3+:CNGS slightly increased in comparison with those of the undoped CNGS crystal. The absorption spectra of Tm3+:CNGS had a strong peak at 793 nm, and its absorption cross-section was 5.01 × 10−21 cm2. The fluorescence spectra at room temperature had a full width at half maximum (FWHM) of 164 nm and a peak wavelength of 1888 nm, and the lifetime of the 3F4 upper energy level of the laser was 2.345 ms. Its good thermal properties, large emission linewidth, and ease of growth indicate that a Tm3+:CNGS single crystal could have the potential to be a good laser gain medium. [ABSTRACT FROM AUTHOR]

A new TbNbO4 single-crystal with a monoclinic structure has been grown successfully using the Czochralski method for the first time. The material belongs to the space group C2/c, with unit-cell parameters of a = 7.173(3) Å, b = 11.186(5) Å, c = 5.156(2) Å and β = 131.082(3)°. The thermal properties of the as-grown TbNbO4 crystal, including specific heat, thermal expansion coefficient, thermal diffusion coefficient, and thermal conductivity, were measured systematically. The TbNbO4 crystal exhibits strong anisotropic thermal expansion; a negative thermal expansion along the c direction is presented, and a zero thermal expansion coefficient in some directions can be obtained. The emission and absorption spectra were also measured. The strongest emission peak in the green spectral domain of TbNbO4 corresponding to the 5D4→7F5 transition of Tb3+ is located at 549 nm. In the range of 350–1500 nm, the as-grown TbNbO4 crystal has low absorption. X-ray photoelectron spectroscopy (XPS) was used to study the valence of the elements in the TbNbO4 crystal; the result shows that there are two different valence states of Tb in the as-grown crystal. [ABSTRACT FROM AUTHOR]

In the field of photocatalytic CO 2 reduction, quantum dot (QD) assemblies have emerged as promising candidate photocatalysts due to their superior light absorption and better substrate adsorption. However, the poor contacts within QD assemblies lead to low interfacial charge transfer efficiency, making QD assemblies suffer from unsatisfactory photocatalytic performance. Herein, a novel approach is presented involving the construction of strongly interfacial fused CdS QD assemblies (CdS QD gel) for CO 2 reduction. The novel CdS QD gel demonstrates outstanding photocatalytic performance for CO 2 methanation, achieving a CH 4 generation rate of ≈296 µmol g -1 h -1 , with a selectivity surpassing 76% and an apparent quantum yield (AQY) of 1.4%. Further investigations reveal that the robust interfacial fusion in these CdS QDs not only boosts their ability to absorb visible light but also significantly promotes charge separation. The present work paves the way for utilizing QD gel photocatalysts in realizing efficient CO 2 reduction and highlights the critical role of interfacial engineering in photocatalysts., (© 2024 Wiley‐VCH GmbH.)

Electrochemiluminescence (ECL) represents a widely explored technique to generate light, in which the emission intensity relies critically on the charge-transfer reactions between electrogenerated radicals. Two types of charge-transfer mechanisms have been postulated for ECL generation, but the manipulation and effective probing of these routes remain a fundamental challenge. Here, we demonstrate the design of quantum dot (QD) aerogels as novel ECL luminophores via a versatile water-induced gelation strategy. The strong electronic coupling between adjacent QDs enables efficient charge transport within the aerogel network, leading to the generation of highly efficient ECL based on the selectively improved interparticle charge-transfer route. This mechanism is further verified by designing CdSe-CdTe mixed QD aerogels, where the two mechanistic routes are clearly decoupled for ECL generation. We anticipate our work will advance the fundamental understanding of ECL and prove useful for designing next-generation QD-based devices., (© 2022 Wiley-VCH GmbH.)