Electrochemical reduction of CO2 to carbon-containing fuels possesses the potential to solve the environmental issues caused by excess CO2 in the atmosphere. Herein, we introduce a ternary ...Au-CDots-C3N4 electrocatalyst for efficiently reducing CO2 to CO. The ternary catalyst exhibited significantly enhanced activity and stability for CO2 electroreduction in comparison with pure Au NPs. The Au-CDots-C3N4 electrocatalyst demonstrates a high CO FE of ∼79.8% at −0.5 V and a 2.8-fold enhancement of current density (with the Au loading only 4 wt %) at −1.0 V relative to pure Au NPs. The DFT calculations and experimental observations indicate that the high activity toward CO2RR originates from the synergetic effect among Au NPs, CDots, and C3N4 and the capability of H+ and CO2 adsorption from CDots. The long-term stability tests demonstrate that the electrocatalyst can be used for over 8 h without obvious deactivations and maintained its activity over 60 days under normal conditions.
While polycyclic aromatic hydrocarbons (PAHs) are now accepted to be abundant in interstellar space, the abundance and influence of superhydrogenated PAHs (HPAHs) in the interstellar medium (ISM) are ...still under investigation. HPAHs may act as catalysts for or reactants in small-molecule formation via hydrogen abstraction reactions, H2 evaporation, and carbon skeleton fragmentation. Here, we present a gas-phase infrared (IR) action spectroscopy study of the HPAH 4, 5, 9, 10-tetrahydropyrene (THP; C16H14), performed at the Free Electron Lasers for Infrared eXperiments facility. IR action spectroscopy was performed on the THP cation, protonated THP, and their fragments produced by collision-induced dissociation in the range from 600 to 1800 cm−1. Calculated IR spectra, at the density functional theory level, agree with experimental IR spectra to a high degree and were utilized to determine molecular structures of the HPAH fragments. Molecular dynamics simulations compared with experimental mass spectra reveal favorable HPAH fragmentation pathways. Molecular hydrogen (H2) is observed to be a primary fragment of THP+H+ with superhydrogenated duo groups. This contrasts the notion that HPAHs typically undergo carbon skeleton fragmentation leading to CxHy formation. These observations show that lowered symmetry and duo or trio aliphatic groups on HPAHs uniquely change their IR spectra, stability, and fragmentation patterns. As a result, these species may contribute to H2 formation in the ISM.
The demand for catalyst with higher activity and higher selectivity is still a central issue in current material science community. On the basis of first-principles calculations, we demonstrate that ...the catalytic performance of the Pd–TiO2 hybrid nanostructures can be selectively promoted or depressed by choosing the suitable shaped Pd and TiO2 nanocrystals. To be more specific, the catalytic activities of Pd nanoparticles enclosed by (100) or (111) facets can be promoted more significantly when dosed on the TiO2(001) than on TiO2(101) under irradiation. Such theoretical prediction has then been further verified by the experimental observations in which the Pd(100)–TiO2(001) composites exhibit the highest catalytic performance toward the activation of oxygen among all the other shaped hybrid nanostructures. As a result, the selection of facets of support materials can provide an extra tuning parameter to control the catalytic activities of metal nanoparticles. This research opened up a new direction for designing and preparing catalysts with enhanced catalytic performance.
Growth and meat quality are concerned issues in aquaculture. The inhibition of MSTN can lead to significant muscle proliferation in mammals, as well as a decrease in muscle fat content. In fish, the ...effect of MSTN inhibition on muscle fat content is ambiguous. In this study, we constructed transgenic red carp with Larimichthys crocea MSTN1 propeptide (LcMSTN1 propeptide) to study how the inhibition of MSTN1 affects the growth and muscle fat content in fish. Southern Blotting showed that LcMSTN1 propeptide was integrated into the red carp genome. In muscle tissue, the expression of MSTN1 propeptide in transgenic red carp was significantly higher than that of non-transgenic red carp (P < 0.001). The mRNA levels of growth-related genes, MyoD, MyoG and MyHC, in the muscle tissue of transgenic red carp were also significantly higher than those in non-transgenic red carp (P < 0.01). However, there was no significant difference in both muscle fat content and the mRNA levels of lipid metabolism-related genes FAS and LPL between transgenic and non-transgenic red carps. Microscopical observation showed that the muscle fiber diameter in transgenic red carp was significantly larger than that of non-transgenic red carp, implying hypertrophy of muscle fibers. These results indicate that LcMSTN1 propeptide can promote the muscle growth, and does not affect muscle fat content in transgenic red carp, which is different from mammals.
•We constructed transgenic red carp with Larimichthys crocea MSTN1 Propeptide.•Muscle growth-related parameters were significantly larger in transgenic red carp.•Muscle fat contents and lipid metabolism didn't change significantly.
Surface-supported coupling reactions between 1,3,5-tris(4-formylphenyl)benzene and aromatic amines have been investigated on Au(111) using scanning tunneling microscopy under ultra-high-vacuum ...conditions. Upon annealing to moderate temperatures, various products, involving the discrete oligomers and the surface covalent organic frameworks, are obtained through thermal-triggered on-surface chemical reactions. We conclude from the systematic experiments that the stoichiometric composition of the reactants is vital to the surface reaction products, which is rarely reported so far. With this knowledge, we have successfully prepared two-dimensional covalently bonded networks by optimizing the stoichiometric proportions of the reaction precursors.
Context.
Fragmentation is an important decay mechanism for polycyclic aromatic hydrocarbons (PAHs) under harsh interstellar conditions and represents a possible formation pathway for small molecules ...such as H
2
, C
2
H
2
, and C
2
H
4
.
Aims.
Our aim is to investigate the dissociation mechanism of superhydrogenated PAHs that undergo energetic processing and the formation pathway of small hydrocarbons.
Methods.
We obtain, experimentally, the mass distribution of protonated tetrahydropyrene (C
16
H
15
+
,
py
+ 5
H
+
) and protonated hex-ahydropyrene (C
16
H
17
+
,
py
+ 7
H
+
) upon collision-induced dissociation (CID). The infrared (IR) spectra of their main fragments are recorded by infrared multiple-photon dissociation (IRMPD). Extended tight-binding (GFN2-xTB) based molecular dynamics (MD) simulations were performed in order to provide the missing structure information for this experiment and to identify fragmentation path ways. The pathways for fragmentation were further investigated at a hybrid density functional theory (DFT) and dispersion-corrected level.
Results.
A strong signal for loss of 28 mass units of
py
+ 7
H
+
is observed both in the CID experiment and the MD simulation, while
py
+ 5
H
+
shows a negligible signal for the product corresponding to a mass loss of 28. The 28 mass loss from
py
+ 7
H
+
is assigned to the loss of ethylene (C
2
H
4
) and a good fit between the calculated and experimental IR spectrum of the resulting fragment species is obtained. Further DFT calculations show favorable kinetic pathways for loss of C
2
H
4
from hydrogenated PAH configurations involving three consecutive CH
2
molecular entities.
Conclusions.
This joint experimental and theoretical investigation proposes a chemical pathway of ethylene formation from fragmentation of superhydrogenated PAHs. This pathway is sensitive to hydrogenated edges (e.g., the degree of hydrogenation and the hydrogenated positions). The inclusion of this pathway in astrochemical models may improve the estimated abundance of ethylene.
The computational cost of accurate quantum chemistry (QC) calculations of large molecular systems can often be unbearably high. Machine learning offers a lower computational cost compared to QC ...methods while maintaining their accuracy. In this study, we employ the polarizable atom interaction neural network (PaiNN) architecture to train and model the potential energy surface of molecular clusters relevant to atmospheric new particle formation, such as sulfuric acid–ammonia clusters. We compare the differences between PaiNN and previous kernel ridge regression modeling for the Clusteromics I–V data sets. We showcase three models capable of predicting electronic binding energies and interatomic forces with mean absolute errors of <0.3 kcal mol −1 and <0.2 kcal mol −1 Å −1 , respectively. Furthermore, we demonstrate that the error of the modeled properties remains below the chemical accuracy of 1 kcal mol −1 even for clusters vastly larger than those in the training database (up to (H 2 SO 4 ) 15 (NH 3 ) 15 clusters, containing 30 molecules). Consequently, we emphasize the potential applications of these models for faster and more thorough configurational sampling and for boosting molecular dynamics studies of large atmospheric molecular clusters.
The conversion of light alkanes to olefins (e.g., ethylene, propylene, or butylene) is crucial to the chemical industry. ZrO2 with oxygen vacancies has recently been regarded as a promising catalyst ...for the direct dehydrogenation of light alkanes. However, the intrinsic mechanism of the effect of oxygen vacancies on catalytic performance has not been completely understood yet, and ZrO2 without promoters generally displays poor activity toward the direct dehydrogenation of light alkanes. In this work, we demonstrate that the oxygen vacancies in ZrO2 can be poisoned by H atoms during the dehydrogenation of light alkanes, and we report a strategy for stabilizing the oxygen vacancies in ZrO2 by Ga2O3. Experimental results and theoretical calculations indicate that ZrO2 with oxygen vacancies is responsible for dehydrogenation, while Ga2O3 prevents the poisoning of oxygen vacancies by dissociated hydrogen atoms which, in the absence of the Ga2O3 component, blocks further dehydrogenation. Consequently, the optimal Zr0.26Ga1 catalyst exhibits superior propane dehydrogenation performance to the industrial Pt–Sn catalyst, the state-of-the-art catalyst for the direct dehydrogenation of light alkanes. We anticipate this work may shed light on both the fundamental research of catalysis and the chemical industry.
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