查找使用阿拉丁产品的科研文献

Photoinduced Metastable Asymmetric Cu Single Atoms for Photoreduction of CO2 to Ethylene

Qingyu Wang,Yida Zhang,Minxi Lin,Hengwei Wang,Yu Bai,Chengyuan Liu,Junling Lu,Qiquan Luo,Gongming Wang,Hai-Long Jiang,Tao Yao,Xusheng Zheng

Metastable structures are promising candidates for efficient catalysis owing to abundant active electronic states, strong electronic coupling with reactants, and energetic preference. Exerting the value of metastable structures while evading the difficulty in direct synthesis remains challenging. Herein, it is reported that light irradiation enables the generation and maintenance of the metastable state over copper single atoms for efficient carbon dioxide reduction. Under irradiation with light, photogenerated electrons transit to Cu-3 d orbits and initiate d -orbital rearrangement. The initial symmetric Cu 1 ─O 4 coordination converts to the metastable asymmetric structure of Cu 1 ─O 2+1 , and is reversibly restored after removing the light. The photoinduced metastable intermediate of Cu 1 ─O 2+1 promotes the Cu single-atom catalyst to deliver an ethylene yield rate of 60.4 µmol g cat. −1 h −1 . Mechanistic studies reveal that Cu 1 ─O 2+1 possesses stronger adsorption capability for reactants and intermediates. The reaction energy barrier over Cu 1 ─O 2+1 also shows an obvious decline compared to that over Cu 1 ─O 4 .

Magnetic and optoelectronic modulation of Cu-MOF-74 films by quantum dots

Zhimin Mao,Su-Yun Zhang,Duo Zhao,Xiaoliang Weng,Chenxu Kang,Hui Fang,Yu-Jia Zeng

The development of metal–organic framework (MOF) materials with multifunctionalities has boosted their prospects in the fields of spintronics and optoelectronics. However, incorporating magnetic and optoelectronic properties in MOF materials remains challenging. Herein, the in situ synthesis of Cu-MOF-74, a typical one-dimensional linear magnet, is systematically investigated, which shows ferromagnetic and antiferromagnetic interactions along the axial chain direction, and overall tilted antiferromagnetism at low temperatures. In particular, the introduction of SnS:Co quantum dots (QDs) enhances the antiferromagnetic coupling, which increases the phase transition temperature of the MOF from 7.8 K to 275 K at 1000 Oe. In addition, it is demonstrated that Cu-MOF-74 possesses both magnetic and optoelectronic properties. It is found that the responsivity and detectivity of the Cu-MOF-74 photodetector are both significantly improved by the SnS:Co QDs. This research provides promising methods for concurrent improvement of the magnetic and optoelectronic properties of MOF materials, advancing in-depth research on the MOF film as a new type of semiconductor for spintronic and optoelectronic devices.

CO2 Cycloaddition under Ambient Conditions over Cu–Fe Bimetallic Metal–Organic Frameworks

Hua-Qing Yin,Ming-Yang Cui,Hao Wang,Yuan-Zhao Peng,Jia Chen,Tong-Bu Lu,Zhi-Ming Zhang

Carbon dioxide cycloaddition into fine chemicals is prospective technology to solve energy crisis and environmental issues. However, high temperature and pressure are usually required in the conventional cycloaddition reactions of CO2 with epoxides. Moreover, metal active sites play a vital role in the CO2 cycloaddition, but it is still unclear. Herein, we select the isostructural MOF-919-Cu-Fe and MOF-919-Cu-Al as models to promote the performance and clarify the effects of metal type on the CO2 cycloaddition. The MOF-919-Cu-Fe with exposed Fe and Cu Lewis acid sites reaches the CO2 cycloaddition with over 99.9% conversion and over 99.9% selectivity at room temperature and a 1 bar CO2 atmosphere, 3.0- and 52.6-fold higher than those of the MOF-919-Cu-Al with Al and Cu sites (33.8%) and the 1H-pyrazole-4-carboxylic acid, Fe, and Cu mixed system (1.9%), respectively. The proposed mechanism demonstrated that the exposed Fe3+ sites facilitate the ring opening of epoxide and CO2 activation to boost the CO2 cycloaddition reaction. This work provides a new insight to tune the catalytic sites of MOFs to achieve high performance for CO2 fixation.

Photo-Tuned Cu/Cu2O/CdS/PPy Heterojunctions for Hg2+ Sensing in Seawater

Minggang Zhao,Zhensen Liang,Ming Li,Hongzhi Cui,Ye Ma

Defect-rich Cu@CuTCNQ composites for enhanced electrocatalytic nitrate reduction to ammonia

Na Zhou,Jiazhi Wang,Ning Zhang,Zhi Wang,Hengguo Wang,Gang Huang,Di Bao,Haixia Zhong,Xinbo Zhang

Electrochemical conversion of nitrate (NO 3 − ) pollutants into chemical feedstock and fuel ammonia (NH 3 ) can contribute to sustainable mitigation of the current severe energy and environmental crises. However, the electrocatalytic NO 3 − reduction to NH 3 (NRA) involves a sluggish multielectron and proton transfer process that competes with the hydrogen evolution reaction (HER) in aqueous media, imposing great challenges in developing highly selective catalysts for NRA. In this study, we developed a copper and copper-tetracyanoquinodimethane composite catalyst (Cu@CuTCNQ), which possesses a high density of copper vacancy defects. This catalyst has been proven to be efficient for NRA through an in situ electrochemical reconstruction method. The structural evolution of CuTCNQ during NRA was investigated by in situ Raman spectroscopy, which indicated an accelerated charge transfer from the CuTCNQ substrate to the derived Cu, which facilitated the adsorption activation of NO 3 − . The obtained Cu@CuTCNQ exhibited an excellent catalytic performance for NRA, with a Faradaic efficiency of 96.4% and productivity of 144.8 μmol h −1 cm −2 at −0.6 V vs . a reversible hydrogen electrode, superior to Cu nanoparticle counterparts and most Cu-based catalysts. Cu vacancy defects and sufficient interfacial charge transfer synergistically optimize the charge distribution of Cu active sites, reduce the energy barrier for NO 3 − adsorption, and promote deoxidation and hydrogenation processes, thus enhancing NRA and selectivity.

Combustion process of a promising catalyst [Cu(Salen)] for HMX-CMDB propellants

Wenzhe Ma,Yanjing Yang,Yuxin Jia,Dongxiao Fu,Fengqi Zhao,Kangzhen Xu

Metal organic complexes are regarded as a series of promising combustion catalysts for solid rocket propellants. Their effects on the combustion performance of propellants are closely related to the reaction mechanism. Here, the metal–organic complex Cu(Salen) was investigated as a candidate material for the combustion catalyst of the HMX-added composite modified double-base propellant (HMX-CMDB). The combustion performance of the propellant was found to be evidently enhanced in the presence of Cu(Salen) compared with the propellant samples containing Benzoic-Cu or without catalyst. The addition of Cu(Salen) can improve the burning rate and combustion efficiency of the propellant – and greatly reduce the burning rate pressure index. Analysis shows that the addition of Cu(Salen) can increase the combustion area, flame brightness and combustion surface uniformity of the propellant to a higher degree. The sample can spray more beams of bright filaments on the flat combustion section, and the amount of gas generated by decomposition also greatly increases. In addition, Cu(Salen) shows amazing advantages in improving the surface of the propellant and the temperature gradient of the combustion flame.

Preparation and Photocatalytic Properties of CQDs-Modified 26-Facet Cu/Cu2O Composites

Sun Wenwen,Guo Ruyue,Shi Chaojie,Li Xuechen,Wu Jiayi,Tian He,Li Huayi,He Jie,Yang Zhengchun,Li Jiahui,Sun Shanfeng

In this study, we prepared carbon quantum dots (CQDs)-modified 26-facet Cu/Cu 2 O composites and investigated their photocatalytic degradation effect on methyl orange (MO). The microstructure and composition of the reduction products were analyzed. The test results validate the successful modification of CQDs on the surface of Cu/Cu 2 O composites. Further, through electrochemical performance analysis among the materials with different thiourea dioxide (TD) contents, 3TD (n × 0.00075 mol of thiourea dioxide is defined as nTD) exhibits the strongest electron transfer ability; thus, 3TD was selected to further combine with CQDs to examine the photocatalytic performance of Cu/Cu 2 O composites. We analyzed the photocatalytic behavior of the composites by monitoring the degradation of the MO solution. Based on the photocatalytic performance test, the CQDs/3TD composite exhibits excellent photocatalytic activity. Following 120 min of visible light irradiation, the degradation rate of MO with the addition of loaded CQDs increased from 25 to 73%. Materials with both adsorption and photocatalytic properties were successfully prepared, which resolved the regeneration of adsorbents to a certain extent and further accelerated the degradation of dyes. Graphical Abstract

Twistable and tailorable Cu-doped SnO2@PANI textile for wearable ammonia sensing

Longjun Guo,Wei Liu,Chunqing Wang

Herein, a twistable and tailorable NH 3 sensor utilizing hollow porous Cu-doped SnO 2 @PANI (PCS) composite was assembled on a flexible non-woven fabric substrate by in-situ polymerization technique and its gas sensing performance was tested at room temperature (∼25 °C). The results indicated that the well-designed PCS sensor to 50 ppm NH 3 exhibited six times higher response (25.4) than the pristine PANI sensor (4.5). The PCS flexible sensor still possessed a response (1.53) for 10 ppb NH 3 , and the detection limit could reach 5.2 ppb for NH 3 . Meanwhile, the PCS flexible sensor demonstrated excellent flexibility with response decreases of only 1.97 % after 1000 times bending (120°), and 2.11 % after 100 times folding (150°) and long-term stability through 42 days of monitoring (maintaining 98.4 % response). Furthermore, the PCS sensor displayed insensitivity to relative humidity (20 % − 75 % RH), and the low sensing temperature could reach − 15 °C. The enhanced sensing performance of the PCS sensor was attributed to the synergistic effect of the vital role of abundant oxygen vacancy and − OH groups, as well as the hollow porous interconnected structure and the p-n heterojunction between Cu-doped SnO 2 and PANI. This work provides more opportunities to design smart wearable devices for detecting ppb-level NH 3 at room temperature.

Enhanced CO Affinity on Cu Facilitates CO2 Electroreduction toward Multi-Carbon Products

Xiaotong Li,Minkai Qin,Xiuju Wu,Xiangzhou Lv,Jianghao Wang,Yong Wang,Hao Bin Wu

Electrochemical CO 2 reduction reaction (CO 2 RR) is a promising strategy for waste CO 2 utilization and intermittent electricity storage. Herein, it is reported that bimetallic Cu/Pd catalysts with enhanced *CO affinity show a promoted CO 2 RR performance for multi-carbon (C2+) production under industry-relevant high current density. Especially, bimetallic Cu/Pd-1% catalyst shows an outstanding CO 2 -to-C2+ conversion with 66.2% in Faradaic efficiency (FE) and 463.2 mA cm −2 in partial current density. An increment in the FE ratios of C2+ products to CO  for Cu/Pd-1% catalyst further illuminates a preferable C2+ production. In situ Raman spectra reveal that the atop-bounded CO is dominated by low-frequency band CO on Cu/Pd-1% that leads to C2+ products on bimetallic catalysts, in contrast to the majority of high-frequency band CO on Cu that favors the formation of CO. Density function theory calculation confirms that bimetallic Cu/Pd catalyst enhances the *CO adsorption and reduces the Gibbs free energy of the C  C coupling process, thereby favoring the formation of C2+ products.

Carbon nanotube films embedded with Cu@C nanocubes for electromagnetic interference shielding

Jinhong Ye,Yanqin Wang,Liqiang Luo,Kunpeng Qian,Jianyu Zhou,Miao Miao,Xin Feng

Flexible carbon tube films for electromagnetic interference (EMI) shielding are assembled by mixing the well-aligned Cu@C core-shell nanocubes with multi-walled carbon nanotubes (MWCNTs). The Cu@C core-shell nanocubes are achieved by the thermal pyrolysis of polyvinylpyrrolidone (PVP) coating on Cu 2 O nanocubes. With the optimal PVP concentration of 1.5 mg/mL, the Cu@C/MWCNTs composite film with ultra-thin thickness (52.2 μm) displays good conductivity of 12.5 S cm −1 and excellent specific EMI shielding value of 510.73 dB mm −1 , which is higher than the pure MWCNTs film (439.50 dB mm −1 ) under the same weight condition. Moreover, the 1.5 mg/mL-Cu@C/MWCNTs composite film exhibits highly mechanical repeatability after being bended for 10,000 cycles. The carbon layers protecting metal nanoparticles can partly replace precious carbon nanotubes to construction highly flexible composite film with anticipated electrical conductivity, which have a good application prospect for thin, lightweight and flexible EMI shielding fields. Graphical

Multicomponent hydroxides supported Cu/Cu2O nanoparticles for high efficient photocatalytic ammonia synthesis

Huaiwei Zhang,Yifan Chen,Ying Pan,Liang Bao,Jing-yuan Ge

Environmentally friendly photocatalytic N 2 fixation process has attracted considerable attention. Developing efficient photocatalysts with high electron-hole separation rates and gas adsorption capacities remains quite challenging. Herein, a facile fabrication strategy of Cu-Cu 2 O and multicomponent hydroxide S-scheme heterojunctions with carbon dot charge mediators is reported. The rational heterostructure   brings excellent N 2 absorption ability and high photoinduced electron/hole separation efficiency, and the ammonia produced yield reach above 210 µmol·g cal -1 ·h −1 during the nitrogen photofixation process. More superoxide and hydroxyl radicals are generated simultaneously in the as-prepared samples under light illumination. This work offers a reasonable construction method to further develop suitable photocatalysts for ammonia synthesis .

An investigation for H2/N2 adsorptive separation in SIFSIX-2-Cu-i

Hui Zhang,Qiang Fu,Hongyun Qin,Xia Chen,Qicheng Zhang,Zixu Dong,Haoyuan Li,Shoudong Wang,Ming Wang

Hydrogen recovery from ammonia purge gas is a desirable method to relieve the pressure of increasing demand for hydrogen. Metal-organic frameworks (MOFs) are promising adsorbents for the separation of the H 2 –N 2 mixture. However, the separation of the H 2 –N 2 mixture using MOFs remains challenging due to the lack of adsorptive mechanism. Herein, the adsorption mechanism of the H 2 –N 2 mixture in SIFSIX-2-Cu-i has been systematically investigated with the method of a combination of excess adsorption experiments, molecular simulations , and DFT calculations. In the Grand Canonical Monte Carlo (GCMC) simulations, the polarizable force field was first applied to the adsorption of pure H 2 or N 2 and H 2 –N 2 mixture in SIFSIX-2-Cu-i. Ab Initio Molecular Dynamics (AIMD) was performed to investigate the distribution of the guest molecules in the pores of SIFSIX-2-Cu-i. Finally, Density functional theory (DFT) calculations were performed to predict the transfer of charge between MOF and guest molecules. Results revealed two binding sites of H 2 or N 2 in SIFSIX-2-Cu-i. A relatively high thermodynamic adsorption selectivity for N 2 over H 2 has been observed in SIFSIX-2-Cu-i. Furthermore, SIFSIX-2-Cu-i also exhibits a greater affinity with N 2 than with H 2 , which is probably because of the stronger induction interactions between F2 atoms and N 2 molecules. These findings are of significance to guide the design of the new highly selective adsorbents for the separation of H 2 /N 2 .