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At present, the exploration of renewable energy is a huge challenge, and water electrolysis is regarded as a promising method for producing hydrogen. However, the hydrogen evolution reaction (HER) has been hampered due to expensive Pt-based catalysts. Herein, the Fe 2 P-coated Ni 2 P/Co 2 P nanospheres with yolk-shelled structure were successfully synthesized according to a facile approach of doping transition metal elements and phosphating on the template Ni-Co nanospheres, successively. All samples were tested as HER catalysts at various pH environments. The results showed that the Fe 2 P-Ni 2 P/Co 2 P possesses superior electrocatalytic ability and good stability. The Fe 2 P-Ni 2 P/Co 2 P achieved the lower η onset (overpotential at 1.0 mA cm−2) of 36.6, 64.2, and 65.9 mV, η 10 (overpotential at 10 mA cm−2) of 89.7, 125, and 212 mV, and Tafel slopes of 48.0, 60.3, and 135 mV dec−1 in acidic, alkaline, and neutral solutions, respectively, exhibiting an excellent electrocatalytic activity of the multicomponent phosphides for HER. [Display omitted] • Yolk-shelled nanospheres Fe 2 P-Ni 2 P/Co 2 P was synthesized by a template method. • The synergistic effect was used to improve the electrocatalytic performance. • Fe 2 P-Ni 2 P/Co 2 P had large surface area and high catalytic activity for HER. • Fe 2 P-Ni 2 P/Co 2 P had satisfactory HER performance over a wide pH range. [ABSTRACT FROM AUTHOR]

The mechanisms of dehydrogenation reactions as important processes in methanol to aromatics (MTA) have been controversial. Recent work on the active center for dehydrogenation at either Lewis acid site (LAS) or Brønsted−Lewis (B−L) acid synergistic site is a matter. The dehydrogenation processes on L−acid site (GaO+) or B−L acid site (H+ − GaO+) over GaO+/HZSM-5 with different Lewis acid locations for n -hexene to 1,5-hexadiene, as well as cyclohexene to benzene have been researched by applying the density functional theory (DFT) method. The results reflect that active center of dehydrogenation reactions is B−L acid synergistic site through B−L acid synergy mechanism. All elementary steps including C−H bond activation, the formation of H 2 , hydrogen transfer as well as the regeneration of B−acid site are easy to proceed. However, the isomerization for carbonium ions from GaO+ to skeleton oxygen of zeolites is relatively difficult. The analysis shows that isomerization is influenced by the structural and electronic properties of carbonium ions chemisorbed on zeolites. Lewis acid strength of GaO+/HZSM-5 and energy gap between HOMO and LUMO on adsorption complexes are appropriate descriptors for the C−H bond activation. The rate constants analysis indicates that increasing temperature is more favorable for C−H bond activation. Further considering that C−H bond activation occurred preferentially than isomerization, it could be a critical initial step to primarily screen catalysts. [Display omitted] • The active center of dehydrogenation is B−L acid (H+−GaO+) synergistic site. • C−H bond activation and isomerization are key processes. • Lewis acid strength and energy gap are descriptors for C−H bond activation. [ABSTRACT FROM AUTHOR]

The methylation of toluene with methanol is an important process for the preparation of p-xylene (PX). The modification of Ni-containing species in HZSM-5 can improve the yield of PX. However, the active site existence form of Ni is unclear. The intrinsic reaction mechanisms for methylation of toluene with methanol over HZSM-5 with NiOH+ and Ni2+ as Lewis acid have been investigated. The results indicate that the introduction of Ni2+ decreases the activity for the methanol dissociation, whereas NiOH+ enhances the activity with a reduction in activation energy of 100.7 kJ/mol. Furthermore, the generation of three xylenes, as well as the conversion of PX to 1,2,4-Trimethylbenzene (1,2,4-TMB) have also been studied over NiOH+/HZSM-5. It is shown that PX is most easily formed with the lowest energy barrier of 84.8 kJ/mol in four products, implying the introduction of NiOH+ in HZSM-5 favors the formation of PX. In addition, molecular dynamics simulations show that toluene reacts with methanol to form xylenes mainly at the intersection of channels. PX exhibits a much higher self-diffusion coefficient than MX and OX when the temperature rises from 498 to 698 K. It can be concluded that NiOH+ is the active Ni-containing species and NiOH+/HZSM-5 is an excellent catalyst for the production of PX via the methylation of toluene with methanol. [Display omitted] • NiOH+/HZSM-5 has high activity for methanol dissociation. • The lower activation energy is needed for PX formation than that for MX, OX and 1,2,4-TMB. • The more negative charge methanol receives, the more easily it dissociates. • NiOH+/HZSM-5 (T7-2) exhibits excellent channel shape selectivity to PX. [ABSTRACT FROM AUTHOR]

Formaldehyde (CH 2 O) is an indoor hazardous gas and a respiratory marker for lung cancer patients, thus its adsorption and detection are of particular significance. 2H-MoS 2 has a wide range of applications in gas sensors. However, its pristine form is chemically inert and not suitable for the adsorption and detection of CH 2 O. Here, we systematically investigated the adsorption and gas-sensing properties of defective 2H-MoS 2 to CH 2 O based on first-principles calculations. The S vacancy, substitutional doping and adsorption of transition-metal (TM) atoms in the MoS 2 monolayer are considered. We find that the S vacancy effectively enhances the adsorption of CH 2 O and results in significant charge transfer. The substitutional doping of TM atoms on both S and Mo sites is hard to form in equilibrium conditions for the high formation energy. The adsorption of TM atoms on MoS 2 can easily occur for the rather low adsorption energy. Cr and Mn energetically prefer to be adsorbed above the S site, while V, Fe, Co, Ni and Cu energetically prefer to be adsorbed above the Mo site. The TM-adsorbed MoS 2 can then strongly adsorb CH 2 O molecules and results in significant charge transfer, acting as a gas-sensing candidate material for the detection and adsorption of CH 2 O. The adsorption configurations, density of states, adsorption energy, charge transfer and charge density differences are calculated and discussed. These results are of significance to adsorb the toxic CH 2 O gas and design its gas sensors using MoS 2. [ABSTRACT FROM AUTHOR]

• High temperature reduces H 2 consumption in diesel hydrotreating process. • The reduction of H 2 consumption is calculated when temperature varies. • Massive H 2 consumption reduction is achieved while ensuring diesel product quality. • Impact on catalysts caused by reducing H 2 consumption is limited. Reducing hydrogen (H 2) consumption massively while ensuring the ultra-strict product quality is the most critical and extremely challenging issue in diesel hydrotreating process. In this work, the effect of operating parameters (including reaction temperature, reaction pressure, hydrogen/oil (H 2 /oil) volume ratio and liquid hourly space velocity (LHSV)) on H 2 consumption were systematically studied first. Most importantly, the reduction of H 2 consumption caused by temperature elevation was calculated upon satisfying the requirements of content of sulfur (S) and polycyclic aromatic hydrocarbons (PAHs) in the diesel quality standards (S≯10 mg/kg, PAHs≯7%) using feedstock with different properties. Results showed that H 2 consumption was reduced by 23.1% when the temperature reached 401 °C (compared with temperature being 365 °C) using a diesel feed whose S content, N content and density were 9759.1 mg/kg, 147.1 mg/kg and 0.8626 g/cm3, respectively, while the impact on the catalysts activity, structure and coke deposition behavior was relatively little which was proven by the XPS, TEM, CAT-CS and TG-MS studies on the fresh and spent sulfide catalysts. The significant reduction of H 2 consumption was attributed to the different thermodynamic behavior of S and aromatic compounds at relatively high temperature which led to a slightly decrease in hydrodesulfurization (HDS) conversion while a significantly drop in hydrodearomatization (HDA) conversion. This is a promising method to effectively reduce H 2 consumption which can greatly benefit the future industrial applications in producing ultra clean diesel products with ultra-low H 2 consumption. [ABSTRACT FROM AUTHOR]

• A 3-D temperature reconstruction strategy for 2-D infrared images is proposed. • The strategy was validated in both laboratory and simulated-engine conditions. • Error analysis shows an average error of 2.3 % C in the 3-D point cloud. Infrared thermography is a commonly used non-contact temperature measurement technique for thermal diagnostics of gas turbine blades. However, the infrared camera only provides two-dimensional images, which is not conducive to accurately locating temperature anomalies on the turbine blade surface. To overcome the limitations of two-dimensional infrared images, this paper proposes a three-dimensional temperature reconstruction strategy for turbine blades using infrared thermography and the CAD model of the blade. The key to reconstruction is obtaining the relative pose between the blade and the camera. Existing pose estimation methods are not suitable for infrared images of turbine blades. Therefore, the proposed strategy combines the Perspective-n-Point (PnP) algorithm with an optimization algorithm, allowing for the acquisition of the pose with limited feature points and edges. The PnP algorithm is employed for the initial pose estimation, followed by the optimization algorithm to refine the pose, ensuring it meets the requirement for reconstruction. The proposed strategy was validated at both laboratory conditions and simulated-engine conditions (773 K, 1 MPa). Results indicate that the strategy can effectively achieve the three-dimensional reconstruction of two-dimensional infrared images. Error analysis demonstrates an average positional error of 2.3 % of the chord length in the reconstructed three-dimensional point cloud. The developed strategy for reconstructing a three-dimensional temperature field based on infrared images holds practical significance for future thermal diagnostics of the gas turbine. [ABSTRACT FROM AUTHOR]

The methodology of sugaring out–assisted liquid–liquid extraction (SULLE) coupled with high-performance liquid chromatography–fluorescence detection was devised for quantifying bisphenol A (BPA) and bisphenol B (BPB) in beeswax. The effectiveness of SULLE was methodically explored and proved superior to the salting out–assisted liquid–liquid extraction approach for beeswax sample preparation. The analytical performance underwent comprehensive validation, revealing detection limits of 10 μg/kg for BPA and 20 μg/kg for BPB. The method developed was employed to analyse commercial beeswax (n = 15), beeswax foundation (n = 15) and wild-build comb wax (n = 26) samples. The analysis revealed BPA presence in four commercial beeswax samples and three beeswax foundation samples, with the highest detected residue content being 88 ± 7 μg/kg. For BPB, two beeswax foundation samples were positive, with concentrations below the limits of quantification and 85 ± 4 μg/kg, respectively. No bisphenols were detected in wild-build comb wax. Furthermore, the bisphenol removal efficacy of two recycling methods—boiling in water and methanol extraction—was assessed. The findings indicated that after four recycling cycles using water boiling, 9.6% of BPA and 29.2% of BPB remained in the beeswax. Whereas methanol extraction resulted in approximately 7% residual after one recycling process. A long-term study over 210 days revealed the slow degradation of bisphenols in comb beeswax. This degradation fitted well with a first-order model, indicating half-lives (DT 50) of 139 days for BPA and 151 days for BPB, respectively. This research provides the first report on bisphenol contamination in beeswax. The low removal rate during the recycling process and the gradual degradation in beeswax underscore the significance of bisphenol contamination and migration in bee hives along with their potential risk to pollinators warranting concern. Furthermore, the developed SULLE method shows promise in preparing beeswax samples to analyse other analytes. [Display omitted] • Sugaring-out assisted liquid-liquid extraction was proposed for preparing beeswax. • Occurrence of bisphenols in beeswax was reported for the first time. • Removal rate of bisphenols in beeswax recycling was revealed. • Bisphenols show slow degradation in comb beeswax. [ABSTRACT FROM AUTHOR]

Developing an efficient EM wave absorbing material that can broadband absorb EM waves in a wide thickness range is a significant challenge. Herein, we report a multi-scale heterogeneous Co/C composite foam with a three-dimensional (3D) lamellar network to address this challenge. The internal structure of melamine foam (MF) is engineered via carboxymethyl cellulose (CMC) in-situ lamella formation to guarantee excellent impedance matching. Meanwhile, the CMC lamellar network extends the EM wave transmission path. The MOF-derived particles grow uniformly in the lamellar network, covering channels of EM wave transmission, which significantly enriches the EM wave loss mechanism and enhances attenuation capability. Benefiting from the synergistic effect of the 3D lamellar network and multi-scale heterogeneous carbon source, an EM absorber strikes a balance between impedance matching and absorption efficiency. As a result, Co/C@MC delivers an effective absorption bandwidth (EAB) that is more than 8 GHz in the whole range of thicknesses from 3.5 to 8 mm, Ni/C@MC exhibits an EAB of 8.5 GHz at 3.3 mm and Fe/C@MC shows the optimal reflection loss of −76.9 dB at 2.5 mm. This work provides a lamellar network/regional enhancement unit strategy for preparing ultra-efficient broadband EM wave absorbing materials. [Display omitted] • A novel 3D lamellar network is successfully constructed to achieve a balance between impedance matching and attenuation capability. • ZIF67 in situ grows in the melamine skeleton and lamellar network. • The RL min is up to −73.6 dB and the corresponding EAB reaches 15.4 GHz in the microwave band. • The EAB reaches 8 GHz in the whole range of thicknesses from 3.5 to 8 mm. [ABSTRACT FROM AUTHOR]