ACS Catalysis
·
2019
·
IF 12.221
Hongquan Fu,Kuntao Huang,Guangxing Yang,Yonghai Cao,Hongjuan Wang,Feng Peng,Qiang Wang,Hao Yu
Nitrogen dopants on carbon materials play vital roles in metal-free carbon catalysis, while the role of pyridinic nitrogen (NP) or graphitic nitrogen (NG) is still on debate. In this work, N-doped carbon nanotubes were employed to catalyze the oxidation of styrene (SOR) with tert-butyl hydroperoxide as oxidant. We observed a significant enhancement of SOR activity caused by the incorporation of nitrogen dopants when the N content was lower than 3.51% but a decline of activity at higher N contents. At N content up to 7.51%, even worse performance than that on N-doped carbon nanotubes with 0.98% N content was observed. This behavior was rationalized by thorough density functional theory calculations. Different catalytic functions of NP and NG were revealed. More significantly, a synergistic effect between NP and NG was demonstrated when they are quite close, which is unbeneficial for the catalytic activity due to the very high energy barriers. The finding may pave a way to the rational design of high-performance metal-free carbon catalysts.
研究领域:
催化化学
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材料科学
·
理论计算
✓ 已验证
产品关联
DOI
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
·
2024
·
IF 5.3
Yuwen Deng,Zaili Xiong,Jijun Guo,Bingzhi Liu,Meirong Zeng,Zhandong Wang,Zhongyue Zhou,Wenhao Yuan,Fei Qi
Elucidating the oxidation chemistry of polycyclic aromatic hydrocarbons (PAHs) aids in understanding the degradation reaction processes of PAHs, as well as their competitive roles in PAH growth. In this work, ozone-assisted oxidation of indene , the smallest prototype PAH molecule, was investigated in an atmospheric jet stirred reactor at 400–550 K. Ab initio quantum chemistry calculations were conducted to characterize the oxidation kinetics of indene and interpret the experimental observations. Fingerprint oxidation products including 2-(2-oxoethyl) benzoic acid, 2-(formylmethyl) benzaldehyde , 1,2-indanedione and 1-indanone were identified by synchrotron vacuum ultraviolet photoionization mass spectrometry . The initial C 9 H 8 O 3 adduct resulting from O 3 -addition to indene exhibits high instability and is primarily detected as 2-(2-oxoethyl)benzoic acid following ozonolysis reactions. Minor amounts of vinylhydroperoxide were also observed as isomeric products of the C 9 H 8 O 3 adduct. Theoretical calculations indicate that indene ozonolysis is highly structure-dependent, where the conformation of the C 9 H 8 O 3 adduct determines the configuration of the resulting Criegee intermediates (CI). The distinctive reaction pathways introduced by the bifunctionalized characteristics of indene-derived large CIs are emphasized in this study. syn -Configuration CI features more conversion pathways compared to anti -CI due to the interaction between CI functionality and the neighboring aldehyde group, among which the bicyclic ring-closure reaction yielding secondary ozonide is most favored. The dioxirane intermediates generated from anti -CIs can undergo the Crossed Acid-forming channel to yield the target acid products, which provides an alternative way for dioxirane conversion. Further theoretical analyses demonstrate that ozonolysis is not the exclusive mechanism for indene oxidation under O 3 -assisted conditions. Instead, it is accompanied by low-temperature reactions initiated by OH/O 2 , leading to key products such as 2-(formylmethyl) benzaldehyde and 1-indanone. The present work aims to unravel the elusive chemistry involved in the O 3 -initiated oxidation of indene, providing new insights into the distinctive kinetics introduced by large bifunctionalized CIs in the ozonolysis of structurally similar PAHs.
研究领域:
化学动力学
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环境科学
·
量子化学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2020
·Vol. 16
·期 36
·2002433
·
IF 11.459
Shuyi Shen,Tao Ke,Krishnamoorthy Rajavel,Kun Yang,Daohui Lin
The environmental stability of 2D MXene flakes must be systematically studied before their further application. Herein, the colloidal dispersibility and photochemical stability of delaminated Ti 3 C 2 T x MXene flakes modified with hydrazine (HMH) and KOH and with water as the control (HMH-Ti 3 C 2 , KOH-Ti 3 C 2 , and H 2 O-Ti 3 C 2 , respectively) are experimentally and theoretically studied. Modification greatly increases the dispersibility of Ti 3 C 2 T x flakes. Their critical coagulation concentrations are 28.7, 106, and 49.1 m m NaCl, and their Hamaker constants are 23.7 × 10 −21 , 19.1 × 10 −21 , and 37.7 × 10 −21 J, respectively; the colloidal interaction follows the classical Derjaguin–Landau–Verwey–Overbeek theory. HMH-Ti 3 C 2 and KOH-Ti 3 C 2 exhibit higher photochemical stability, as indicated by their stronger resistance to oxidation under UV and visible light irradiation. Changes in their physicochemical properties and the generation of reactive oxygen species (ROS) are assayed. Spin-polarized density functional theory calculations and molecular dynamics simulations are used to determine the mechanisms underlying the differences in the photochemical stability of Ti 3 C 2 T x flakes. K + ions protect the flakes from oxidation by acting as a middle layer to reduce the coupling between Ti 3+ and ROS, while HMH provides stronger protection by absorbing photoelectrons or reacting with ROS. These findings provide new insight into the environmental transformation and design of functional MXenes.
研究领域:
材料科学
·
环境科学
·
化学
✓ 已验证
DOI
PubMed
高影响因子
THERMOCHIMICA ACTA
·
2017
·
IF 2.236
Jing Liu,Rujuan Li,Mengya Guo,Hairong Tao,Donglan Sun,Chengxing Zong,Chunjing Liu,Fengzhi Fu
We recently found that the introduction of benzene ring as connection block improved the thermal stability of glycerol carbonate derivatives. To further explore how polysubstitution on benzene influences their thermal stability, another two derivatives, benzene-1,3,5-tricarboxylic acid tris-(2-oxo-[1,3]dioxolan-4-ylmethyl) ester (BATE1) and benzene-1,2,4,5-tetracarboxylic acid tetrakis-(2-oxo-[1,3]dioxolan-4-ylmethyl) ester (BATE2), were synthesized and characterized by a combined TG–FTIR and theoretical calculation. TG results showed that both BATE1 and BATE2 had three weight loss stages. FTIR spectra of evolved gases and the bond dissociation energy for the two compounds indicated that during the pyrolysis process, the C C, C O bonds of five-membered cyclic carbonate fractured preferentially to produce volatile carbonates and CO 2 , and then the nearby C O bond of esters continued to crack to produce more fragments. Finally, benzene ring still remains in the solid pyrolysis products. Therefore, improving the thermal stability of compound cannot be achieved simply by increasing the number of substituents on the benzene ring.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Zhicheng Chen,Yuchan Deng,Guangxing Yang,Ya-Nan Zhu,Qiao Zhang,Zhiting Liu,Yonghai Cao,Feng Peng
M–N–C materials as catalysts are widely used in hydrocarbon oxidation, the intrinsic role of which has not been well illustrated. In this study, M–N–C (M = Fe, Co, Cu, Zn) as model catalysts for cumene oxidation through theoretical calculations and experiment validation are studied. The changes of Gibbs free energy (ΔG) for the elementary steps demonstrate that the activation of cumene/O2 molecules and the decomposition of cumene hydroperoxide (CHP) play a significant role in cumene oxidation. The interactions between M–N–C and cumene, O2, and CHP are fully investigated. There are strong interactions between FeNC/CoNC and O2, cumene, and CHP, in which the activation of cumene and O2 and the decomposition of CHP occurred more easily, thereby promoting the catalytic activity. Although the adsorption energy over CuNC (ΔECuNC) for cumene is comparable to ΔECoNC, the O2 molecule is physically adsorbed on CuNC, which leads to a lower activity than those of FeNC and CoNC. Metal tetraphenyl-porphyrins (MTPPs) with the corresponding structure of M–N–C as the catalysts are used to catalyze the oxidation of cumene. A volcanic curve correlation between the average adsorption energy (ΔEav.) and the conversion rate of cumene catalyzed by MTPPs is observed. The kinetic experiments confirmed that CoTPP displays the best catalytic activity, due to the high k80 and low activation energy for the crucial steps of cumene oxidation, which is consistent with the theoretical results.
研究领域:
化学
·
催化科学
·
理论计算
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Meng Jin,Yanyan Liu,Xian Zhang,Jialu Wang,Shengbo Zhang,Guozhong Wang,Yunxia Zhang,Huajie Yin,Haimin Zhang,Huijun Zhao
We report ultrafine Cu x Pt y alloying nanoparticles anchored on carbon black (Cu x Pt y /C) for selective electrocatalytic hydrogenation of nitrobenzene (Ph-NO 2 ) at ambient conditions. The experimental and theoretical studies reveal that as electrocatalyst, the optimal Cu 3 Pt/C with adjusted electronic structure can effectively facilitate the adsorption and activation of Ph-NO 2 . The results indicate that the acidic media is favorable for the production of aminobenzene irrelevant to the applied potential, while the electrocatalytic hydrogenation products are highly dependent on the reduction potential in the alkaline media. As a result, the Cu 3 Pt/C can afford almost 100 % conversion of Ph-NO 2 into azoxybenzene with ∼99 % selectivity at 0.3 V (vs. RHE) and aminobenzene with ∼99 % selectivity at -0.3 V (vs. RHE) in 1.0 M KOH, respectively. The theoretical calculations provide a comprehensive understanding of the selective electrocatalytic hydrogenation mechanisms of Ph-NO 2 relative to electrolyte pH and applied potential, matched well with the experimental results.
研究领域:
化学
·
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 11
·6179-6186
·
IF 3.108
Huaqi Zhan,Yongjun Hu,Pengchao Wang,Jiaxin Chen
Morpholine (NH(CH2CH2)2O) is a typical six-membered aliphatic heterocyclic compound. Herein, infrared plus vacuum ultraviolet (IR/VUV) single photon “soft” ionization spectroscopy was employed to study the structures of neutral morpholine and its monohydrated clusters. Theoretical calculations revealed that the structures containing equatorial-chair and axial-chair conformations were the most stable conformers in the gas phase, and this was confirmed by IR spectral analysis. Analysis of the observed and calculated spectra of the monohydrated clusters suggested that multiple conformers may co-exist in the molecular beam, and that the water molecule acts as a hydrogen donor. In the most stable structure, the hydrogen atom of the water molecule is bound to the NH group of the equatorial-chair conformer of morpholine. Moreover, the water molecules simultaneously serve as hydrogen bond donors for the NH group and interact with the CH group weakly. It is suggested that the weak intermolecular CH⋯O interaction is also responsible for the molecular stability.
研究领域:
化学
·
物理化学
·
分子光谱学
✓ 已验证
产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2021
·Vol. 9
·期 3
·440-447
·
IF 6.569
Yunqiao Guo,Yalan Deng,Ting Zheng,Ling Huang,Daojiang Gao,Jian Bi,Guohong Zou
Two novel molybdenyl carbonates named Cs2MoO3(CO3) and Cs3MoO4(HCO3) have been synthesized using a facile solvent evaporation method. Centrosymmetric Cs2MoO3(CO3) features one-dimensional chains composed of MoO6 octahedra and CO3 groups, while noncentrosymmetric Cs3MoO4(HCO3) displays a zero dimensional framework constructed with dispersive MoO4 tetrahedra and HCO3 groups. Remarkably, although these two compounds have the same chemical composition, their band gaps differ as large as 1.04 eV, which is 3.38 eV for Cs2MoO3(CO3) and 4.42 eV for Cs3MoO4(HCO3). The molecular orbital hybridization between MoO6 and CO3 in 1D chains narrows the band gap of Cs2MoO3(CO3), which is further supported by the electron density difference map through theoretical calculations.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Shuibo Wang,Biao Wu,Qiuju Zhang,Yiming Li,Lin Zhu,Hongbo Yu,Hongfeng Yin
The selective hydrogenation of cinnamaldehyde (CAL) to prepare cinnamyl alcohol (COL) is challenging as the unwanted hydrogenation of C C bond in CAL is thermodynamically more favorable than the hydrogenation of C O bond. We herein designed core–shell structured nanoparticles (NPs) that consisted of Pt cores and Sn shells to catalyze the CAL to COL conversion. By simply changing the amount of Sn precursor, we generated Pt@Sn NPs with different Sn shell thickness and catalytic performance. Among the samples, Pt@Sn/SiO 2 with Pt/Sn of 1/1 achieved the highest CAL conversion (87.2 %) as well as the COL selectivity (95.4 %), which were 5-fold and 6-fold, respectively, higher than those of Pt/SiO 2 . This catalyst was also applicable to the hydrogenation of other α, β-unsaturated aldehyde and unsaturated carbonyl compounds. Both experiments and theoretical calculations indicated that the strong Pt-Sn interaction and the partial coverage of Pt by Sn facilitated their adsorption of C O bonds, thus enhancing the conversion of CAL and the selectivity towards COL.
研究领域:
催化化学
·
材料科学
·
理论计算
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2024
·
IF 5.3
Ling Pan,Song Ye,Ruihao Huang,Meiyan Wang,Peixuan Lin,Haoran Zhang,Deping Wang
Faujasite (FAU) zeolites with abundant exchangeable sites are ideal hosts for the intake of Ag+ and the stabilization of highly luminescent silver nanoclusters (Ag NCs), while theoretical calculations on the spectral characteristics, charge states, and electronic energies of Ag NCs that are confined inside FAU zeolite were seldom reported. In this research, the Na-type FAU zeolites with varying silicon-to-aluminum (Si/Al) ratios were first synthesized with the hydrothermal method and then applied as matrixes to stabilize Ag NCs to obtain tunable emissions. With the decrease in the Si/Al ratio, the Ag NCs show red-shifted emission from 515 to 548 nm and broadened photoluminescence of excitation (PLE) and photoluminescence (PL) spectral profile. The time-dependent density functional theory (TD-DFT) method was carried out to probe the effect of Al substitution on the charge states and the optical properties of Ag NCs confined inside the double-six ring (D6r) cavity. The simulated results of the absorption spectra and energy levels suggest that the S1 → S0 transition of the monovalent Ag3+ cluster is responsible for the visible emission, and the increased full width at half-maximum (fwhm) of the PLE and PL spectra in the low Si/Al ratio FAU zeolites is due to the inhomogeneous broadening brought by the increased isomer numbers of the Al-substituted neutral zeolite framework. It is noted that the peak of the simulated absorption spectra red-shifted with the decrease in the Si/Al ratio, which is consistent with the experimental observation. This research provided an effective method for the manipulation of Ag NC emission in FAU zeolites through framework cation substitution and meanwhile theoretically explained the Si/Al ratio dependence of tunable emission properties, which may benefit the design of zeolite-confined Ag NCs with desirable optical performances.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Tong Ye,Yajie Wang,Xiang Yao,Hongbin Li,Taishi Xiao,Kun Ba,Yi Tang,Changlin Zheng,Xiaoyong Yang,Zhengzong Sun
The precise design and synthesis of active sites to improve catalyst’s performance has emerged as a promising tactic for electrochemistry. However, it is challenging to combine different types of active sites and manipulate them simultaneously at atomic resolution. Here, we present a strategy to synthesize Re atom-doped Cu twin boundaries (TBs), through pulsed electrodeposition and boundary segregation. The Re-doped Cu TBs demonstrate a highly efficient nitrogen reduction reaction (NRR) performance. Re-doped Cu TBs showed a turnover frequency of ∼5889 s–1, ∼800 times higher than the pure Cu TB active centers (∼7 s–1). In addition to the “acceptance–donation” activation of N2 molecules, theoretical calculations also reveal that the Re–Re dimer on TB can boost the NRR and impede the hydrogen evolution reaction synchronously, rendering Re-doped Cu TB catalysts with high NRR activity and selectivity.
研究领域:
材料科学
·
电化学
·
催化反应
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Jingjing Zhang,Yang Feng,Lixia Ling,Caiping Ma,Jungang Wang,Riguang Zhang,Maohong Fan,Bo Hou,Debao Li,Baojun Wang
The direct conversion of syngas to ethanol faces challenges due to catalyst inefficiencies and low ethanol yield. Bulk alloys with an appropriate atomic ratio can exhibit excellent catalytic performance. In this work, a series of Rh x Ni y (111) with different Rh/Ni ratios was rationally designed, and the ethanol preparation from syngas was explored based on density functional theory (DFT) calculation and microkinetic analysis. The results show that Rh 1 Ni 1 (111) was screened out to show optimum catalytic performance for ethanol production. This was attributed to a moderate quantity of charge transfer from Ni to Rh atoms, and a medium distance from the d -band center to the Fermi level. Further, to verify the catalytic performance of the catalysts at a Rh: Ni ratio of 1: 1, 1Rh1Ni/γ-Al 2 O 3 catalyst was prepared and its catalytic performance for ethanol preparation from syngas was investigated by comparing it with that of Rh/γ-Al 2 O 3 and Ni/γ-Al 2 O 3 . The catalytic performance of 1Rh1Ni/γ-Al 2 O 3 has been further confirmed to be preferred over Rh/γ-Al 2 O 3 and Ni/γ-Al 2 O 3 , achieving a 23.0 % CO conversion rate with 31.2 % ethanol selectivity.
研究领域:
催化化学
·
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）