CATALYSIS LETTERS
·
2021
·Vol. 152
·期 4
·1145-1159
·
IF 3.186
Yu Guiyun,Zhao Yefan,Zhang Yulong,Wu Jiaxin,Liu Chao
There are increasing concerns of environmental-pollution and energy issues. Herein, an exfoliation-restacking process was firstly employed to synthesize H + -restacked H + Ti 2 NbO 7 − nanosheets (HTNS), and then heated with melamine at 510 °C to obtain direct Z-scheme layered N-doped H + Ti 2 NbO 7 − /g-C 3 N 4 (TCN) heterojunctions with an increased specific surface area. Two-dimensional (2D) g-C 3 N 4 material was in-situ formed on the surface of HTNS to achieve a layered heterostructure between two components, which could maximize interfacial contact area and minimize interfacial distance for the efficient charge carrier separation. Simultaneously, the surface of HTNS was doped by nitrogen atoms to form visible-light-responsive N-doped HTNS. All TCN x ( x = 1, 2 and 3) composites exhibited the enhanced photocatalytic activity for both hydrogen (H 2 ) production and rhodamine B (RhB) degradation. As an optimal sample, the resulted TCN2 composite exhibited the best photocatalytic efficiency for H 2 production and RhB degradation. The enhanced photocatalytic activity was assigned to the combined effects of layered heterojunction, N-doping and large specific surface area. According to trapping experiments and electron spin resonance (ESR) spectra, the holes (h + ), superoxide (·O 2 − ) and hydroxyl (·OH) radicals were responsible for photocatalytic RhB degradation and especially the ·O 2 − was the key active specie. A possible charge transfer pathway was analyzed in detail. This work will hopefully provide some guidance on designing Z-scheme layered heterojunction photocatalyst systems with highly photocatalytic efficiency. Graphical Abstract Direct Z-scheme layered N-doped H + Ti 2 NbO 7 − /g-C 3 N 4 heterojunction photocatalysts were constructed by a three-step exfoliation-restacking-calcination process, showing the highly photocatalytic efficiency for H 2 production and RhB degradation under visible light due to the synergistic effects of layered heterojunction, N-doping and large specific surface area.
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JOURNAL OF MATERIALS SCIENCE
·
2021
·Vol. 56
·期 30
·17167-17177
·
IF 4.22
Gan Xiaoyan,Zhao Wenhui,Xu Tianye,Liang Yun,Guo Liling,Liu Hanxing
Two-dimensional (2D) organic–inorganic perovskite hybrid materials with enhanced stability have attracted wide attention in optoelectronic field in recent years. Efforts of exploring new 2D perovskites with various organic or inorganic components have been devoted to further improve their solar cell efficiencies. In this work, three structurally similar spacer cations of phenylethylammonium (PEA), 4-bromophenylethylammonium (BPEA) and 4-chlorophenylethylammonium (CPEA) are selected to prepare multilayered 2D perovskites. It is found that the introduction of halogen atoms in the organic cations positively influences the film quality, light absorption, charge transport, device performance and moisture stability of the resulting perovskites. The (BPEA) 2 (MA) 4 Pb 5 I 16 and (CPEA) 2 (MA) 4 Pb 5 I 16 perovskites exhibit efficiencies of 7.38% and 10.88%, respectively, which are much higher than that of (PEA) 2 (MA) 4 Pb 5 I 16 (3.98%). Owning to the larger size and bigger electronegativity of halogen atom in spacer cations, the PCE of unsealed BPEA- and CPEA-based 2D perovskite devices maintains 73% and 63% of their original efficiency after 720 h exposure to 60% humid air, while the PEA-based 2D device decreases to 52% of its initial PCE. Our work demonstrates new insight to modify the quality and stability of 2D perovskite hybrids, highlighting the validity of molecule design of organic cations in improving the efficiency and stability of 2D perovskite solar cells.
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Catalysts
·
2018
·Vol. 8
·期 8
·326
·
IF 3.465
Peng Sun,Jun Zhang,Wenxiu Liu,Qi Wang,Wenbin Cao
In this paper, the Langmuir-Hinshelwood (L-H) model has been used to investigate the kinetics of photodegradation of gaseous benzene by nitrogen-doped TiO2(N-TiO2) at 25 °C under visible light irradiation. Experimental results show that the photoreaction coefficientkpmincreased from 3.992 × 10−6mol·kg−1·s−1to 11.55 × 10−6mol·kg−1·s−1along with increasing illumination intensity. However, the adsorption equilibrium constantKLdecreased from 1139 to 597 m3·mol−1when the illumination intensity increased from 36.7 × 104lx to 75.1 × 104lx, whereas it was 2761 m3·mol−1in the absence of light. This is contrary to the fact thatKLshould be a constant if the temperature was fixed. This phenomenon can be attributed to the breaking of the adsorption-desorption equilibrium by photocatalytically decomposition. To compensate for the disequilibrium of the adsorption-desorption process, photoreaction coefficientkpmwas introduced to the expression ofKLand the compensation form was denoted asKm.KLis an indicator of the adsorption capacity of TiO2whileKmis only an indicator of the coverage ratio of TiO2surface. The modified L-H model has been experimentally verified so it is expected to be used to predict the kinetics of the photocatalytic degradation of gaseous benzene.Keywords:modified L-H model;N-TiO2;photocatalytic degradation;benzene
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Polymer Chemistry
·
2015
·Vol. 6
·期 48
·8259-8269
·
IF 5.52
Haiyan Peng,Guannan Chen,Mingli Ni,Yan Yan,Jiaqing Zhuang,V. A. L. Roy,Robert K. Y. Li,Xiaolin Xie
Holographic polymer dispersed liquid crystals (H-PDLCs) pertain to one type of intriguing switchable electro-optical device, and there is a constant need to quantitatively understand the photopolymerization kinetics and gelation process during the formation of H-PDLCs for the purpose of improving the diffraction efficiency and driving voltage. Herein, we quantitatively investigate the effect of the photoinitibitor composed of 3,3′-carbonylbis(7-diethylaminocoumarin) (KCD) and N-phenylglycine (NPG), with initiation and inhibition functions simultaneously generated under monochromatic illumination, on the formation of H-PDLCs. The outcomes reveal that an augmentation of KCD loading from 0.3 × 10−3 to 1.4 × 10−3 mol L−1 dramatically promotes the photopolymerization rate and monomer conversion. Reversely, a further increase in KCD content drastically depresses photopolymerization. The numerical deduction shows that the kinetics complies with the classical photopolymerization kinetics characteristics in the full range of the KCD content. Counterintuitively, the gelation time almost keeps constant when the KCD content is less than 1.8 × 10−3 mol L−1, and then is able to grow by more than 4 times when the KCD loading further increases. Ketyl radical inhibition, which subsequently results in shortened weight-average chain lengths and increased gel point conversions, is believed to account for the kinetics and exceptional gelation behaviors. H-PDLCs with a scaffolding morphology are formed, and with an augmentation of the KCD content, the segregation degree and diffraction efficiency significantly improve from zero to 64% and 78 ± 11%, respectively, and then level off, allowing for the facile fabrication of glass-free colored 3D images; while the critical driving voltage gradually decreases from 8.9 ± 1.0 to 4.6 ± 0.7 V μm−1.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Lei Wang,Xin Zhang,Yonggang Sun,Yulong Ma,Min Xu,Juan Zhang,Yingbo Zhu,Li Zhu,Song Qiao,Jing Ma,Jinpeng Wei,Feng Lin
Environmental H 2 O has a significant effect on the reaction mechanism and process of VOC oxidation, of which the intrinsic mechanism is hardly reported. Herein, a series of PtCu δ -MnO x catalysts with different strong metal-supported interactions were constructed by replacing some Pt species with Cu species. Among them, the PtCu 3 -MnO x catalyst exhibited superior catalytic performance (T 90 = 170 ℃), high water resistance, and long-term stability. Furthermore, in-situ diffuse reflectance infrared Fourier transform spectroscopy ( in-situ DRIFTs) showed that the acetone oxidation followed synergistic cooperation of the Langmuir-Hinshelwood (L-H) and Mars van Krevelen (MvK) mechanism. Acetone oxidation over PtCu 3 -MnO x occurred via the L-H mechanism producing surface acetate and formate species intermediate. Above 100 °C, adsorbed acetone (i.e., acetate and formate species) reacts with MnO x lattice oxygen according to the MvK mechanism to form CO 2 and H 2 O. When water vapor was present, the L-H mechanism was impaired, inhibiting the deep oxidation of acetone. This research provides an in-depth exploration of how water vapor impacts the reaction mechanism of acetone oxidation. It offers valuable insights for creating dependable catalysts suitable for use in various industrial settings.
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CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Shandi Zhong,Cai Xu,Quanfu Long,Hang Zhou,Jianhai Yang,Jia Guo,Xiaozhong Wang,Liyan Dai
Using O 2 as an oxidant, developing a non-noble metal catalyst for the selective catalytic C–H bond oxidation of p-chlorotoluene is desirable and challenging. In this work, a series of Co, Cr co-doped OMS-2 (Octahedral Molecular Sieve-2) catalysts were prepared by a conventional refluxing method. It was found that the incorporation of Co and Cr improved the catalytic activity for the selective oxidation of p-chlorotoluene to p-chlorobenzaldehyde. Among these catalysts, CoCr/OMS-2 (Co: Cr = 1: 1, mass ratio), the best catalyst, shows that the conversion and the selectivity of p-chlorobenzaldehyde is 94.8 % and 94.3 %, respectively. The enhanced catalytic activity was due to the larger specific surface area and even dispersion of active components. The characterization results also disclosed that the co-doping of Co and Cr increased the oxygen vacancy and enhanced the ability to activate the surface lattice oxygen. Additionally, density functional theory calculations demonstrated that co-doping of Co and Cr promoted the adsorption of p-chlorotoluene and O 2 , and decreased the energy barrier of rate-determining step (the conversion of p-chlorobenzyl alcohol to p-chlorobenzaldehyde). Besides, when H 2 O was added to the reaction system as the second solvent, the activation and dissociation of O 2 , and the formation of p-chlorobenzaldehyde were facilitated, in agreement with the experimental results. This work demonstrated the promotional effect of Co, Cr co-doped into OMS-2 catalyst and the role of H 2 O for the selective oxidation of p-chlorotoluene.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Fangxian Wang,Junwei Yang,Shihao Li,Junwen Liang,Yuwei Wang,Rong Du,Bo Zhou,Qiong Liu,Changping Li
Bromate is a commonly identified carcinogenic and genotoxic disinfection byproduct in water. Electrochemical debromination is an environmentally friendly and effective approach but it often suffers the limited reducing atomic H (H*) ability and high metal catalyst dosage. In this study, a unique composite catalyst comprised of ultra-low loading Cu single atoms (0.016 wt%) and Fe 2 O 3 nanoparticles supported on a Nb 2 C MXene (denoted as Cu 0.2 /Fe 0.1 /Nb 2 C) was synthesized by one-step high-temperature molten salt method. The Cu 0.2 /Fe 0.1 /Nb 2 C significantly outperformed the Nb 2 C, Cu 0.2 /Nb 2 C and Fe 0.1 /Nb 2 C counterparts in the electrochemical debromination with a 94.2 % removal efficiency of bromate. It is revealed that the introducing of Cu single atoms, efficiently promotes the adsorption of H* and inhibition of competitive H 2 evolution. The incorporation of Fe 2 O 3 nanoparticles significantly increased the electronic metal-support interaction effect between the metal components and Nb 2 C, thereby forming a noticeable electronic cloud bridge to facilitate efficient charge transfer. Ultimately, the synergistic interplay between Cu single atoms and Fe 2 O 3 nanoparticles plays a crucial role in achieving the remarkable removal performance of bromate. This work not only presents a significant instance of a synergistic catalyst involving metal single atoms and metal nanoparticles for effective electrochemical debromination but also advances the understanding of the electronic metal-support interaction.
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MOLECULES
·
2024
·Vol. 29
·期 16
·3747
·
IF 4.2
Guanyu Chen,Weixin Zhang,Rongshu Zhu,Yanpeng Chen,Minghu Zhao,Mei Hong
Zeolite-based catalysts efficiently catalyze the selective catalytic reduction of NOxwith methane (CH4-SCR) for the environmentally friendly removal of nitrogen oxides, but suffer severe deactivation in high-temperature SO2- and H2O-containing flue gas. In this work, SSZ-39 zeolite (AEI topology) with high hydrothermal stability is reported for preparing CH4-SCR catalysts. Mild acid leaching with oxalic acid (OA) not only modulates the Si/Al ratio of commercial SSZ-39 to a suitable value, but also removes some extra-framework Al atoms, introducing a small number of mesopores into the zeolite that alleviate diffusion limitation. Additional Co3O4modification during indium exchange further enhances the catalytic activity of the resulting In-Co3O4/H-SSZ-39(OA). The optimized sample exhibits remarkable performance in CH4-SCR under a gas hourly space velocity (GHSV) of 24,000 h−1and in the presence of 5 vol% H2O. Even under harsh SO2- and H2O-containing high-temperature conditions, it shows satisfactory stability. Catalysts containing Co3O4components demonstrate much higher CH4conversion. The strong mutual interaction between Co3O4and Brønsted acid sites, confirmed by the temperature-programmed desorption of NO (NO-TPD), enables more stable NxOyspecies to be retained in In-Co3O4/H-SSZ-39(OA) to supply further reactions at high temperatures.
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PubMed
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
·
2017
·Vol. 23
·期 41
·9831-9837
·
IF 5.317
Qiang Cao,Qing Yin,Qi Chen,Zhi-Bing Dong,Bao-Hang Han
Graphical Removed from the mix : The synthesis of fluorinated iron–porphyrin conjugated porous polymers through direct C−H arylation polymerization is described (see scheme). The application of these polymers as heterogeneous catalysts for Baeyer–Villiger oxidation is also discussed. By considering the high reactivity of fluorinated iron–porphyrin and good stability of porphyrin-based porous polymers, fluorinated iron–porphyrin conjugated porous polymers ( FPOP-3 – 6 ) were synthesized through direct C−H arylation polymerization. The obtained materials are chemically and thermally stable, of which FPOP-3 exhibits the highest Brunauer–Emmett–Teller specific surface area (about 840 m 2 g −1 ). For functional studies of the obtained polymers as heterogeneous catalysts, catalytic transformation of cycloketones into lactones by oxygen through Baeyer–Villiger oxidation was used as a model reaction. Fluorinated phenyl substituents of the iron–porphyrin not only are beneficial to the conversion, but also can stabilize the porphyrin to resist catalyst breakdown. The polymer FPOP-3 , with high porosity, exhibits the best catalytic efficiency and recycling effect. The recovered catalyst also shows good catalytic activities after recycling three times with a small loss in yield.
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PubMed
高影响因子
CEMENT & CONCRETE COMPOSITES
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2024
·
IF 10.8
Guangpeng He,Deyu Kong,Xiaoguang Chen,Shujing Fan,Tao Meng,Jiabin Li
In this paper, low-cost dihydrate gypsum (CaSO 4 ⋅2H 2 O) was used as calcium source together with sodium metasilicate solution to prepare calcium silicate hydrate (C-S-H) gels through a mechanochemical activation strategy by using planetary and vibrational ball-milling. The influences of the prepared C-S-H gels on hydrating and hardening properties of super-retarded cement-based materials with sucrose were investigated. The results showed that CaSO 4 ⋅2H 2 O reacted with sodium metasilicate solution under mechanochemical effect during both planetary and vibrational ball-milling, although CaSO 4 ⋅2H 2 O was just slightly dissolved in water. It was also interestingly found that the C-S-H gels can continuously form while resting for a certain time after ball-milling. Under the mechanochemical activation, the prepared C-S-H gels had complete characteristic diffusion peaks and were composed of layered, flocculent and fibrous structures. While incorporating the prepared C-S-H gels into the super-retarded cement paste with sucrose, the cement hydration was greatly accelerated and the compressive strength of the hardened cement-based materials was also effectively improved at early age as expected. Through X-ray diffraction (XRD) analysis, it was found that C-S-H gels can effectively promote the growth of CH crystals along the (001) and (101) crystal planes. The scanning electron microscopy (SEM) results supported that the C-S-H gels inhibited the refinement of ettringite (AFt) crystals in super-retarded HCP with sucrose, which was more obvious at 28 d.
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INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
·
2025
·
IF 6.4
Wei Yang,Yichao Lin,Yanqi Zhu,Chenxia Zhen,Weihao Tao,Yanlong Luo,Xiujuan Wang
This study aims to investigate the effect of the modification strategy of hexagonal boron nitride (h-BN) on the interfacial heat transfer behavior of the composite. Dual modification of h-BN, including covalent and non-covalent modifications, was achieved by combining 6-aminohexanoic acid (ACA)-assisted wet ball milling and tannic acid (TA) surface deposition. Molecular dynamics (MD) simulations show that the interfacial thermal resistance of the covalently modified and the non-covalently modified regions of the composite system is reduced by 19.7 % and 40.9 %, respectively, and the interfacial thermal conductivity is increased by 24.5 % and 88.0 %, respectively. Meanwhile, thermogravimetric analysis demonstrated a 9 °C and 23.7 °C increase in the maximum weight loss temperature of the dual-modified composites compared to that of the two single-modified composites. The synergistic mechanism of the dual modification strategy in improving the interfacial interaction and enhancing the phonon vibration power spectrum of the composites is revealed by MD simulations. This study contributes to a deep understanding of the thermal conductivity mechanism of filled thermal interface materials. It guides the design of modified filler-filled high thermal conductivity rubber-based composites.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Xuefeng Zhou,Xiaohai Zheng,Jinyu Li,Lijuan Shen,Xiaoyang Pan,Xuhui Yang,Min-Quan Yang
Photocatalytic selective oxidation of benzylic C( sp 3 )-H bonds to high-value oxygenates holds great potential for sustainable organic synthesis, yet remains challenging due to inefficient charge separation and limited substrate activation over conventional photocatalysts. Herein, a C 3 N 4 /PMA 2 PbBr 4 heterojunction is rationally designed via an anti-solvent strategy, integrating 2D PMA 2 PbBr 4 with π-conjugated C 3 N 4 . Experimental and theoretical analyses reveal that the internal electric field induced by band alignment drives spatial charge separation, preserving the powerful holes in the valence band of PMA 2 PbBr 4 for direct C H bond activation and electrons in the conduction band of C 3 N 4 for efficient O 2 reduction. Notably, C 3 N 4 demonstrates enhanced toluene adsorption via π-π interactions, concentrating substrates at reactive interfaces. The synergistic interplay of optimized charge dynamics and molecules activation enhances hole-mediated C H cleavage and radical-driven further oxidation. Consequently, the optimized 5 % C 3 N 4 /PMA 2 PbBr 4 achieves a benzaldehyde production rate of 5783 μmol g −1 h −1 under visible light, outperforming pristine PMA 2 PbBr 4 by a factor of 1.7 and C 3 N 4 of 25.8.
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