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The silicon-aluminum ratio of the molecular sieves is a crucial control index for the quality of synthetic molecular sieves. Here a fast, simple and reliable sample preparation method, referred to as pouring and curing method, is described for determining the silicon-aluminum ratio of high silicon molecular sieves by energy dispersive x-ray fluorescence (EDXRF). Resin is used as the carrier with the addition of a curing agent, so that the sample powder is embedded in the resin matrix. By measuring sixteen random positions of the same cured sample, the homogeneity of the sample was evaluated to ensure the stability of the results. A double logarithmic calibration curve of the analysis line ratio and the corresponding concentration ratio of silicon and aluminum was established according to the binary ratio method. The results by EDXRF and inductively coupled plasma-optical emission spectrometer (ICP-OES) were compared with a relative standard error from 2.934 to 6.777%. The good precision shows that the pouring and curing method is a suitable for measuring the silicon-aluminum ratio of molecular sieves. [ABSTRACT FROM AUTHOR]

Conventional intumescent flame retardants (IFRs) have demonstrated remarkable efficacy in augmenting flame retardancy but often increase smoke release. To improve the smoke suppression effect of IFRs, this study employed a one-pot method to prepare a loaded core–shell flame retardant material, namely APP@PMA–LDH. This was achieved by supramolecular assembly of phytic acid (PA) and melamine (MA) to form melamine phytate (PMA), which was coated onto ammonium polyphosphate (APP) and loaded with layered double hydroxide (LDH). APP@PMA–LDH was then compounded with a carbonized foam agent (CFA) and polypropylene (PP) to produce PP composite materials. The experimental results showed that the sample containing APP@PMA-LD H1.0 (with 1 wt% LDH) exhibited the highest effects, with a substantial reduction of 68.4% in the peak heat release rate and a 59.5% decrease in total smoke production relative to PP. Furthermore, the sample attained a limiting oxygen index of 30.3% and achieved the UL-94 V-0 rating. The analysis revealed that APP@PMA–LDH promotes the development of a dense and stable graphitic char layer on the surface of PP, reducing internal porosity and effectively hindering the emission of flammable volatile substances, thus increasing the flame retardancy and smoke suppression of PP. [ABSTRACT FROM AUTHOR]

The selective conversion of levulinic acid (LA) obtained from lignocellulosic biomass represents a crucial pathway for producing the key value‐added chemical compound γ‐valerolactone (GVL). Herein, we constructed a series of Pt‐based titanium‐silicalite‐1 (TS‐1) bifunctional catalysts modified with rare earth metal Ce through a simple spin‐coating impregnation method, and the catalytic performance was significantly improved compared to the unmodified Pt1.2/TS‐1. Pt0.7‐Ce0.5/TS‐1 exhibited the best aqueous‐phase catalytic activity (with a GVL yield of 99.4%). The introduction of CeOx can reduce the particle size of Pt nanoparticles and promote the formation of electron‐rich Pt species while delivering abundant oxygen vacancies (OV) for the catalysts. The characterization and testing results highlight the synergistic effect of OV and electron‐rich Pt sites on the oriented adsorption and selective hydrogenation of LA, providing new insights into constructing more efficient noble metal‐based zeolite catalysts for biomass conversion. [ABSTRACT FROM AUTHOR]

The development of earth-rich, low-cost, and high-efficiency electrocatalysts toward alkaline hydrogen evolution reactions (HERs) in the water spitting process is extremely desirable yet a huge challenge. In this work, we report the synthesis of novel RuO2/MoS2 electrocatalysts with good conductivity and abundant active sites for efficient HER by uniformly dispersing RuO2 nanoparticles on MoS2 nanosheets. Benefitting from the intense electronic coupling effect endowed with interface modifications, the as-prepared RuO2/MoS2 electrocatalysts exhibited superior performance for HER in 1 M KOH with a very low overpotential of 36 mV at 10 mA cm−2 and a small Tafel slope value of 34.8 mV dec−1. Moreover, the introduction of RuO2 nanoparticles improved the durability of the RuO2/MoS2 electrocatalysts with negligible variation in a 20 h operation. More importantly, the density functional theory (DFT) calculations further revealed the mechanism of strong electronic interaction between RuO2 nanoparticles and MoS2 nanosheets, which contributes to accelerating the H2O dissociation kinetics and optimizing H adsorption Gibbs free energy. This work may provide a deeper understanding for designing efficient HER catalysts through interface modification strategies. [ABSTRACT FROM AUTHOR]

Exploration of levulinic acid (LA) hydrogenation to γ‐valerolactone (GVL) contributes to the conversion from carbohydrates to valuable fuels and chemicals. Here, we obtained a series of ultra‐small PtNix bimetallic composite catalysts encapsulated in silicalite‐1 zeolite (S‐1) via a one‐pot synthesis strategy protected by tetra(p‐carboxyphenyl)porphyrin (TCPP) ligands. The catalytic results showed that PtNi3@S‐1 (TCPP) exhibited the most active catalytic performance (95.7% LA conversion and 93.8% GVL selectivity) under optimized conditions. The characterization results indicate that ligand modification and bimetallic synergy play an important role in enhancing the catalytic activity. The introduction of TCPP provides a guarantee for the homogeneous encapsulation of PtNi3 in S‐1 zeolite at sub‐nanometer size. The electronic interaction of PtNi bimetallic, high dispersibility of active components, improved surface acidity and excellent stability co‐contribute to the satisfactory hydrogenation activity. [ABSTRACT FROM AUTHOR]

Currently, two-dimensional (2D) layered transition metal chalcogenides (TMCs), especially MoS2, are attracting widespread attention in the field of water electrolysis. Unfortunately, the catalytic activity of MoS2 is limited to a few edge sites and by its low conductivity. Herein, MoS2/NiS heterostructures possessing a flower-like morphology were constructed via an accurate thermal treatment process to realize precise interface modification. As expected, through the adjunction of a certain amount of polyvinylpyrrolidone, NiS grew uniformly on the surface of MoS2 nanosheets, thereby forming a large number of visual lattice fringes with a specific interplanar spacing, which promoted a higher electron-transfer efficiency. The better electron-transfer efficiency resulted in a better hydrogen evolution reaction performance, providing an overpotential of 158 mV at 10 mA cm−1, a Tafel slope of 128.1 mV dec−1, and significantly long-term durability. Moreover, density functional theory calculation also showed that the precise interface modification of MoS2/NiS heterostructure exhibited more occupations at the Fermi level, which improved the electrical conductivity. Additionally, the MoS2/NiS catalysts achieved a moderately lower hydrogen adsorption energy (ΔGH*), indicating that it had better catalytic hydrogen evolution performance. This work can be extended to design other catalytic materials and for understanding reactions in the fields of energy conversion through theoretical calculations. [ABSTRACT FROM AUTHOR]

Enhancing the kinetics of electrocatalytic water splitting, including the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), under alkaline conditions is of key importance for producing high purity and renewable hydrogen on a large scale. Owing to their unique structural features, two-dimensional (2D) heterostructures have been regarded as promising next-generation electrocatalysts for overall water splitting. Herein, we successfully synthesized three-dimensional (3D) flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres assembled from heterostructural 2D nanosheets. Benefiting from well-exposed interfaces and favorable diffusion channels, the as-prepared 3D flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres manifest excellent overall water splitting performance in an alkaline solution with a low Tafel slope of 71 and 41 mV dec−1 for oxygen and hydrogen evolution reactions, and show significantly improved long-term durability. Furthermore, the 3D flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres used in both the anode and cathode show a low cell voltage of 1.53 V at a 10 mA cm−2 current density. Using DFT calculations, we found the outstanding chemisorption of hydrogen and oxygen-containing intermediates making Co–Ni–P/MoS2 heterostructures an efficient bifunctional overall electrochemical water splitting catalyst. In summary, this work opens up an important direction for exploring efficient and durable bifunctional electrocatalysts for the overall water splitting. [ABSTRACT FROM AUTHOR]

Flower-like P-doped graphitic carbon nitride (g-C3N4) with a high surface area and porosity has been prepared via a facile, template-free, cost-effective and thermal copolymerization route, using phosphoric acid as the phosphorus source and a cyanuric acid–melamine complex as the supramolecular precursor. It could be found that phosphoric acid could stabilize the three-dimensional character of the as-prepared P-doped g-C3N4 and the g-C3N4 micro-flower consisted of ultrathin nanosheets which possessed abundant mesopores. The unique structure, combined with phosphorus heteroatom doping, promoted the utilization of visible light and improved the separation and mobility of photogenerated charges. The obtained P-doped g-C3N4 exhibited prominent photocatalytic performance in the water splitting for the hydrogen evolution reaction under visible light irradiation. The hydrogen evolution rate reached 256.4 μmol h−1, almost 24 times higher than that of pristine g-C3N4. Meanwhile, a possible mechanism for photocatalytic hydrogen evolution was proposed according to the results. [ABSTRACT FROM AUTHOR]

A feasible strategy is reported for the synthesis of a disk‐like Pt/CeO2‐p‐TiO2 catalyst derived from the titanium‐based metal–organic framework (MOF) MIL‐125(Ti) through a few valid steps. To verify the successful synthesis and structural features of the Pt/CeO2‐p‐TiO2 catalyst, as‐prepared samples were characterized using several techniques. The characterizations demonstrated that MOF‐derived porous TiO2 was appropriate for application as a support owing to its moderate surface area (101 m2 g−1) and suitable pore size (6 nm). Moreover, to study the effect of calcination temperature on the catalytic performance, the obtained catalyst was calcined at various temperatures. It was found that Pt/CeO2‐p‐TiO2 calcined at 550 °C exhibited the highest catalytic performance, evaluated by means of the reduction of 4‐nitrophenol monitored by UV–visible spectra. Furthermore, this catalyst showed good reusability with a conversion of 94% even after six cycles. Finally, a possible reaction mechanism was proposed to explain the reduction of 4‐nitrophenol to 4‐aminophenol over the Pt/CeO2‐p‐TiO2 catalyst. [ABSTRACT FROM AUTHOR]

A novel thermal exfoliation strategy has been proposed to synthesize high-quality Ag/TiO2 head–body nanosnowman nanoparticles (AgTiNPs, with the head and body being single Ag and TiO2 nanoparticles, respectively) for the first time. The obtained samples were characterized with transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and photoluminescence (PL) emission spectra, etc. Results show that loaded Ag nanoparticles could exfoliate with a part of an adjacent caducous TiO2 nanosheet during calcination treatment, thereby fabricating high-quality Ag/TiO2 head–body nanosnowman nanoparticles. The prepared AgTiNPs show a uniform particle size, a high dispersion and enhanced interactions between Ag heads and TiO2 bodies. Compared with calcined Ag/DHS, AgTiNPs exhibit an enhanced photocatalytic performance in the degradation of RhB and solar H2 production due to improved charge carrier separation. The proposed thermal exfoliation strategy might open up a new method for the fabrication of other semiconductor–metal nanosnowman nanoparticles with enhanced photochemical properties. [ABSTRACT FROM AUTHOR]

A novel Pt–TiO2/Ag nanotube photocatalyst has been synthesized successfully via a facile method. TiO2 nanotubes are assembled with numerous ultrathin TiO2 nanosheets and show a highly open structure. The gaps between adjacent TiO2 nanosheets can serve as channels for the access of reactants, accelerating the mass transfer process. During the fabrication process of the Pt–TiO2/Ag nanotube photocatalyst, high‐quality Pt–SiO2 nanotubes are synthesized first with the structure‐directing effect of polyvinylpyrrolidone. Then a TiO2 layer is coated on the outside surface of the silica nanotubes. The introduced titanium species can be converted into TiO2 nanosheet structure during the subsequent hydrothermal treatment, gradually constructing nanosheet‐assembled nanotubes. Lastly, after the introduction of another electron sink function site of Ag through UV irradiation, the Pt–TiO2/Ag nanotube photocatalyst with dual electron sink functional sites is obtained. The specially doped Pt and Ag NPs can simultaneously inhibit the recombination process of photogenerated charge carriers and increase light utilization efficiency. Therefore, the as‐synthesized Pt–TiO2/Ag nanotube catalyst exhibits a high photocatalytic degradation performance for rhodamine B of 0.2 min−1, which is about 3.2 and 5.3 times as high as that of Pt–TiO2 and TiO2 nanotubes because of the enhanced charge carrier separation efficiency. Furthermore, in the unique nanoarchitecture, the nanotubes are assembled with numerous ultrathin TiO2 nanosheets, which can absorb abundant active species and dye molecules for photocatalytic reaction. On the basis of experimental results, a possible rhodamine B degradation mechanism is proposed to explain the excellent photocatalytic efficiency of the Pt–TiO2/Ag nanotube photocatalyst. [ABSTRACT FROM AUTHOR]