APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Mengyang Xu,Chao Sun,Xiaoxue Zhao,Haopeng Jiang,Huiqin Wang,Pengwei Huo
Fabricating the hierarchical heterostructure is efficient way for enhancing CO 2 conversion of semiconductor photocatalysts. Herein, a simple strategy has been employed to prepare several 3D hierarchical CdS/Ni-MOF heterostructure photocatalysts, and the selective photoreduction of CO 2 to CO under simulated sunlight in the gas–solid phase reactor. Among the prepared photocatalysts, 20%-CdS/Ni-MOF shows the best CO yield, which was 16 times and 7 times that of Ni-MOF and CdS, respectively. By controlling the morphology of the catalyst, we found that the significant improvement in photocatalytic activity can be ascribed to the synergistic effect of heterostructure in CdS/Ni-MOF and its unique hierarchical structure, which can improve the efficiency of charge transmission and provides abundant active sites, etc. Finally, the preliminary photocatalytic mechanism was discussed by in situ FTIR and liquid ultraviolet spectrophotometer.
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高影响因子
Advanced Sustainable Systems
·
2022
·Vol. 6
·期 3
·2100380
·
IF 6.737
Zhengyi Li,Hu Li,Song Yang
Catalytic upgrading of CO 2 into value-added chemicals to build the excess carbon cycle is of great significance. In this work, carboxylate-functionalized zeolitic imidazolate framework (F-ZIF-90) with good crystallinity and porosity is constructed from ZIF-90 and employed as a robust heterogeneous catalyst to boost the reductive N -functionalization of various amines with CO 2 to furnish N -formyl compounds (up to 99% yield) in the presence of PhSiH 3 under an ambient environment. The imidazole carboxylate species ( COO - ) can not only activate hydrosilane and CO 2 to form the key intermediate formoxysliane but also activate amines to participate in the N -formylation reaction to obtain the target product. Moreover, it can enhance the catalyst capture and exchange ability toward ambient CO 2 . The powerful adsorption capacity of the F-ZIF-90 catalyst toward CO 2 is conducive to elevating CO 2 concentration around the active species. Theoretical calculations show that the carboxylate-mediated conversion path undergoes the transition state of hydrosilane activation with a relatively lower energy barrier (Δ G = 26.9 kcal mol –1 ). F-ZIF-90 exhibits good thermochemical stability with no obvious activity attenuation after repeated use 5 times. This strategy opens a new avenue based on ZIFs to develop heterogeneous catalysts for reductive upgrading of CO 2 .
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FUEL
·
2020
·
IF 5.578
Bowen Lu,Zewu Zhang,Xiaoshan Li,Cong Luo,Yongqing Xu,Liqi Zhang
Cu catalysts have been widely used in CO 2 utilization due to their low reduction temperature and excellent CO 2 hydrogenation performance. It is important to well design Cu catalyst with high efficiency and durability for CO 2 hydrogenation. In this work, CuCe(rod) catalysts with various Cu contents were prepared. The physicochemical properties of the CuCe(rod) catalysts were described by XRD, TEM, N 2 -physisorption and H 2 -TPR.The effect of Cu content on catalytic performance of CO 2 hydrogenation with CuCe(rod) catalysts was also studied. Results showed that a high Cu content enhanced CO 2 conversion. The 40CuCe(rod) catalyst exhibited the best CO 2 conversion performance. At the reaction temperature of 400 °C, the CO production rate (CO 2 conversion) and CO selectivity based on the 40CuCe(rod) catalyst could reach 1.69 mol/g cat /h (41.1%) and nearly 100%, respectively. The analysis of kinetic measurements revealed that the activation energy of the 40CuCe(rod) catalyst was lower than that of other catalysts with different Cu contents during a reverse water–gas shift reaction. The lower activation energy and the interface structure of Cu-O x -Ce were closely related to CO 2 hydrogenation activity and remarkable stability for 96 h with minimal loss of CO 2 conversion activities.
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NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 32
·13728-13737
·
IF 3.288
Jiaqian Lu,Zhe Zhang,Lin Cheng,Hong Liu
Herein, a series of MoS2-wrapped Mn0.2Cd0.8S nanospheres with different MoS2 content were fabricated via a two-step hydrothermal route. The photocatalytic activity of the as-prepared MoS2/Mn0.2Cd0.8S composites for H2 production and reduction of CO2 under visible light irradiation was investigated. The results demonstrated that the ultra-thin MoS2 nanosheets were uniformly wrapped on the surface of cauliflower-like Mn0.2Cd0.8S nanospheres, and an intimate interfacial contact was formed between MoS2 and Mn0.2Cd0.8S. The MoS2/Mn0.2Cd0.8S hybrids exhibited significantly enhanced photocatalytic activity compared with the pristine Mn0.2Cd0.8S. The optimal MoS2 loading content was determined to be 3.0 wt%, giving a H2 production rate of 335.02 μmol h−1 and a CH3OH production rate of 2.13 μmol h−1, which were around 5.1 and 5.4 times that of bare Mn0.2Cd0.8S, respectively. The superior photocatalytic activity was predominantly attributed to the intimate contacts between Mn0.2Cd0.8S and MoS2, which facilitated the transfer and separation of the photoexcited charge carriers. Moreover, the as-synthesized MoS2/Mn0.2Cd0.8S composites also showed excellent stability. This study demonstrates the great potential of MoS2-wrapped Mn0.2Cd0.8S as a noble-metal-free catalyst for photocatalytic energy conversion.
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SmartMat
·
2022
·Vol. 3
·期 1
·142-150
·
IF 0
Lu Han,Benqiang Tian,Xiangxiang Gao,Yang Zhong,Shengnan Wang,Shuchang Song,Zhili Wang,Ying Zhang,Yun Kuang,Xiaoming Sun
Electroreduction of carbon dioxide into fuels and feedstocks with renewable energy is an attractive route to mitigate carbon emission and solve energy crisis. However, how to improve the selectivity of high-value multicarbon products is still challenging. Here, we demonstrate that the high-index crystalline surface of copper could be designed and obtained through a simple square-wave potential treatment on copper nanowires, which is beneficial to improve the selectivity of multi-carbon products, especially the reaction route towards ethylene. The Faradaic efficiency of C 2+ products can reach nearly 60%, and hydrogen can be suppressed to below 20%. Density functional theory (DFT) calculations reveal that (311) high-index facet can activate CO 2 effectively and promote adsorption of the *COCOH intermediate on copper for ethylene formation, therefore improves the selectivity of ethylene and inhibits the competing hydrogen evolution reaction. This method can be extended to the design of other catalytic systems and has inspirations for other electrochemical catalytic reactions.
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CHEMOSPHERE
·
2020
·
IF 5.778
Dong Xia,Ange Maurice,Antoine Leybros,Jong-Min Lee,Agnes Grandjean,Jean-Christophe P. Gabriel
Removal of brominated flame retardants (BFRs) from polymers before disposal or recycling will alleviate negative environmental effects and ensure safe usage of recycled products. Extraction of BFRs in supercritical CO 2 is appealing but also presents challenges to industries due to limited solubility and lack of kinetic studies. For a more comprehensive evaluation of supercritical extraction potentialities, we (i) developed an on-line pressure apparatus that is compatible with both the FTIR and UV–vis spectrometers to enable kinetic and thermodynamic studies; (ii) studied kinetic extraction involving three conventional and two novel BFRs as well as three typical polymeric matrix. Solubilities were determined using the gravimetric method or X-ray fluorescence. FTIR exhibited a superior applicability compared to UV–vis in the following BFR extraction’s time-dependency binary and ternary systems . We observed that faster stirring speed, higher temperature, and finer particle size can accelerate the overall extraction kinetics. In binary systems, it took less than 2 h to achieve equilibrium for each BFR at 60 °C, 25 MPa and 1000 rpm. In the presence of polymeric matrix, slower extraction kinetics were observed due to the occurrence of competitive dissolution and molecular diffusion within the matrix. Mathematical models derived from irreversible desorption and Fick’s diffusion laws fitted well with the observed extraction kinetics of BFRs, thus enabling us to identify the rate-determining step. The high solubilization rate coefficients that we measured for BFRs revealed that the dynamic extraction process in up-scaling design could compensate for the low solubility with flowing supercritical CO 2 .
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KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2021
·Vol. 38
·期 5
·1032-1042
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IF 3.309
Xu Li,Qin Yu,Liu Liying,Xiao Juntian,Ding Zhongwei
The membrane contactor has been considered an effective device to capture CO 2 , but its performance is limited by membrane wetting phenomena. In this work, the ZIF-8/ZIF-L (zeolitic imidazolate framework) based composite membrane with excellent hydrophobic stability and CO 2 permeability was successfully fabricated by coating the dense layer on the porous PVDF (polyvinylidene fluoride) substrate. The dense layer was developed by evenly incorporating ZIF-8 nanocrystals and ZIF-L nanosheets into the polydimethylsiloxane (PDMS) polymer. The as-prepared membrane possessed competitive hydrophobicity with a water contact angle (WCA) of 131.8°. And after a ten-day immersion test in CO 2 absorbent, the WCA only declined by 9.8%, exhibiting excellent hydrophobic stability. Besides, the CO 2 permeability of the composite membrane was 61.8×10 −8 ·mol·m −2 ·s −1 ·Pa −1 with an ideal CO 2 /N 2 separation factor of ∺20, which was effectively improved in comparison with the control membrane. In the CO 2 absorption experiment, the prepared membrane achieved the competitive CO 2 flux of 3.02×10 −3 ·mol·m −2 ·s −1 when the liquid velocity was 0.25 m·s −1 and displayed robust long-term operating stability. Finally, the AC impedance technique was applied to continuously monitor the wetting state of composite membranes, which further investigated their anti-wetting ability.
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高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Changqing Gui,Zirui Wang,Changjian Ling,Zhongfeng Tang
Molten salt-doped MgO adsorbent is considered one of the most promising CO 2 adsorbents in the field. In this work, MgO-based adsorbents were prepared by one-step calcination using MgCl 2 ·6 H 2 O as magnesium source. The CO 2 adsorption performance of MgO-based adsorbents was investigated via different methods. Results showed that the maximum CO 2 adsorption capacity of MgO doped by LiNO 3 -NaNO 3 -KNO 3 was 57.1% at the CO 2 concentration of 80% and 350 ℃, and the MgO-based adsorbents showed good regeneration. The nanosheet structure of the MgO-based adsorbents decreased with the increase in the number of cycles, whereas the crystal structures of MgO and alkali metal nitrates did not change because of multiple decarbonization. DFT computation revealed selective adsorption of CO 2 on different crystal faces of MgO. The (200) crystal face of molten salt-doped MgO did not have CO 2 trap ability. In addition, the doped nitrate did not directly participate in the reaction but reduced the adsorption energy of MgO carbonation. The adsorption energies of the MgO (220) and (222) crystal faces after doping with nitrate were reduced to − 2.07 and − 3.26 eV, respectively. The overall energy level of adsorption decreased as the number of resonance peaks and the stability of the structure increased. This study explains why MgO currently fails to reach the theoretical adsorption capacity and reveals the underlying mechanism of molten salts.
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高影响因子
Green Energy & Environment
·
2022
·
IF 12.781
Zhengshan Yang,Bowen Deng,Kaifa Du,Huayi Yin,Dihua Wang
Molten carbonate is an excellent electrolyte for the electrochemical reduction of CO 2 to carbonaceous materials. However, the electrolyte–electrode-reaction relationship has not been well understood. Herein, we propose a general descriptor, the CO 2 activity, to reveal the electrolyte–electrode-reaction relationship by thermodynamic calculations and experimental studies. Experimental studies agree well with theoretical predictions that both cations (Li + , Ca 2+ , Sr 2+ and Ba 2+ ) and anions (BO 2 − , Ti 5 O 14 8 − , Si O 3 2 − ) can modulate the CO 2 activity to control both cathode and anode reactions in a typical molten carbonate electrolyzer in terms of tuning reaction products and overpotentials. In this regard, the reduction of C O 3 2 − can be interpreted as the direct reduction of CO 2 generated from the dissociated C O 3 2 − , and the CO 2 activity can be used as a general descriptor to predict the electrode reaction in molten carbonate. Overall, the CO 2 activity descriptor unlocks the electrolyte–electrode-reaction relationship, thereby providing fundamental insights into guiding molten carbonate CO 2 electrolysis.
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高影响因子
RENEWABLE ENERGY
·
2019
·
IF 5.439
Yu Hong,Chengrui Xie,Wanru Chen,Xiang Luo,Kaiqi Shi,Tao Wu
In this study, three primary components of algae (lipid, carbohydrate and protein) and one microalgae (spirulina) were pyrolyzed using a thermogravimetric analyser (TGA) under nitrogen and CO 2 atmosphere at four heating rates . It was found that protein decomposed first, followed by carbohydrate and then lipid. The kinetic study revealed that the lowest activation energy for the initiation of the pyrolysis of ovalbumin (protein) is ∼70 kJ/mol. Oil droplet showed higher activation energy of 266.5 kJ/mol during its pyrolysis in the CO 2 atmosphere, which suggests that algal lipid is more difficult to decompose in the CO 2 atmosphere. However, for the pyrolysis of cellulose (carbohydrate), the activation energy (∼310 kJ/mol) is similar under two different gas atmospheres tested. This study showed that CO 2 atmosphere favors the pyrolysis of algae with high protein content and low lipid content, since the existence of CO 2 promotes the cracking of VOCs (volatile organic compounds) as well as the reaction between VOCs and CO 2 .
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高影响因子
POLYMER
·
2021
·
IF 4.43
Runan Gong,Han Cao,Hongming Zhang,Lijun Qiao,Xianhong Wang
Though cationic waterborne polyurethane (CWPU) has been regarded as an important environmental friendly material, it is hampered by poor water resistance due to incorporation of excessive hydrophilic groups to assure the stability of water dispersion. Here UV-curing in combination with terminal hydrophilicity induced dispersion strategy was employed to prepare water-resistant CWPU from CO 2 -polyol which was an oligoethercarbonate diol from telomerization of propylene oxide and CO 2 . In this system, multiple vinyl ether side chains were incorporated on CWPU backbone using 3-allyloxy-1,2-propanediol as functional chain extender to achieve efficient UV curing, and a small amount of terminal hydrophilicity was designed to ensure the stable dispersion of CWPU. The typical UV-cured CWPU film reached water absorption equilibrium at 72 h, maintaining water absorption rate as low as Ca . 5.8% even immersed in water for 240 h. Moreover, compared with traditional polyester and polyether polyols from petroleum resources, UV-cured CWPU from CO 2 -polyol not only used partially sustainable raw material like CO 2 , but also provided excellent water resistance in corrosive media for a long time (tensile strength retention above 90% for 336 h) due to hydrolysis resistant structure like carbonate and ether units in CO 2 -polyol.
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高影响因子
Materials Today Physics
·
2022
·
IF 11.021
X. Li,Z. Wang,J. Zhang,K. Dai,K. Fan,G. Dawson
The solar driven reduction of carbon dioxide (CO 2 ) to high value-added carbon based fuel is a promising solution to mitidate climate and energy problems, however, improving the adsorption and conversion efficiency of CO 2 in the photoreduction process still faces severe challenges. In this work, Cd 0·7 Zn 0·3 Se solid solution was prepared by cation exchange: selenium (Se) vacancies are produced during ion exchange, which promotes the unsaturated coordination of the surrounding metal atoms. The adsorption of diethylenetriamine (DETA) on the surface limits the growth of Cd x Zn 1- x Se crystallites , resulting in insufficient coordination of the surface atoms, which then become active adsorption sites. Furthermore, a heterojunction was formed with Cu 2 O@Cu to accelerate the separation and transfer of photo-induced carriers of Cd 0·7 Zn 0·3 Se, and the optimized Cd 0·7 Zn 0·3 Se/Cu 2 O@Cu (CZS/CC) step-scheme heterojunction exhibited a CO release activity of 50.5 μmol g −1 h −1 , which is 3.8 and 10.7 times higher than that of Cd 0·7 Zn 0·3 Se and Cu 2 O@Cu, respectively. This work is expected to open up new insight for the regulation of nanostructures and the design of selective catalysts.
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高影响因子
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