CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Fan Fang,Nengjie Feng,Peng Zhao,Chong Chen,Xue Li,Jie Meng,Geng Liu,Li Chen,Hui Wan,Guofeng Guan
The PrBa 0.5 Sr 0.5 Co 0.2 Fe 1.8 O 5+δ double perovskite porous nanotubular webs are prepared by a simple electrospinning technique following calcination. It shows better catalytic activity compared with the bulk PrBa 0.5 Sr 0.5 Co 0.2 Fe 1.8 O 5+δ prepared by citrate method, due to its larger specific surface area and higher utilization of active sites. On basis of this, introducing multiple active sites is conducive to enhancing the catalytic activity. In this work, the PrBa 0.5 Sr 0.5 Co 0.2 Fe 1.8 O 5+δ double perovskite porous nanotubular webs are further reduced at 750 °C in a 10% H 2 /N 2 gas flow, which can give rise to the in situ exsolution of Co core-shell nanoparticles and obtain double active sites. Meanwhile, series of related catalysts are also prepared for comparison, and the physicochemical properties of these catalysts are studied by a lot of characterization techniques. The catalytic performance for soot combustion is evaluated by a temperature programmed oxidation test, which can simulate the soot combustion process. Turn of frequency (TOF) and activation energy ( E a ) are calculated by isothermal studies to further evaluate the activity of the as-prepared catalyst. Among all the prepared catalysts, the PrBa 0.5 Sr 0.5 Co 0.2 Fe 1.8 O 5+δ porous nanotubular webs after reductive treatment at 750 °C in H 2 atmosphere exhibits the best catalytic activity for soot combustion, showing the lowest activation energy and the highest TOF values. Furthermore, its catalytic activity is significantly promoted compared with the bulk-type catalyst. Firstly, it may be associated with the synergistic effects of sufficient Co core-shell nanoparticles and oxygen vacancies in double perovskite functioned as active sites. Secondly, the structure of porous nanotubular webs can make full use of these active sites.
研究领域:
材料科学
·
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2018
·
IF 11.384
Cheng Liang,Qiyi Ma,Haoran Yuan,Yongtao Wang,Jianyong Mao,Zhirong Chen,Jia Yao,Haoran Li
An investigation of aerobic oxidation of 2-methoxy-4-methylphenol to vanillin catalyzed by a number of cobalt salts, complexes, oxides, and hydroxides in alkaline solutions is reported. A good yield of vanillin (90%) was obtained when CoCl2 was used as the catalyst, while a poor yield (6%) was obtained with Co3O4. Unexpectedly, however, the Co3O4 catalytic activity was restored after heating in an alcoholic solution of NaOH for 24 h, producing a good yield of vanillin (85%). The recovered catalytic activity of Co3O4 indicated a conversion of inactivated heterogeneous particles to activated particles. In addition, precipitates were generated when “homogeneous” CoCl2 was employed as a catalyst, making us wonder about the true nature of the catalyst in this reaction. A series of experiments are described, including kinetic studies, filtration tests, centrifugation tests, dynamic light scattering, transmission electron microscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction, for the investigation of the true catalyst under catalytic conditions. The key observations led to the conclusion that the cobalt salts and complexes act as precatalysts that transform to cobalt oxide/hydroxide [CoOx(OH)y] nanoparticles, which is responsible for the benzylic C(sp3)–H oxyfunctionalization of 2-methoxy-4-methylphenol. Additionally, the size of the particles is decisive for catalyst performance. The nature of the active nanoparticles was also studied. With regard to the identification of homogeneous or heterogeneous catalysis, this study provides a complement to existing catalytic reaction types.
研究领域:
化学工程
·
催化科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Energy Materials
·
2026
·
IF 5.5
Xiaoling Peng,Ying Luo,Jiawei Xue,Farzaneh Arabpour Roghabadi,Qiang Wang,Zheng Wang,Hong He
Visible-light-driven CO2 reduction coupled with H2O oxidation is an attractive route toward artificial photosynthesis; however, its realization is often limited by inefficient charge separation in a CO2-reduction photocatalyst, sluggish interfacial charge transfer in Z-scheme systems, and insufficient CO2 activation. Herein, we report a visible-light-driven Z-scheme system in which CoOx−Ag dual-cocatalyst-modified Bi4TaO8Cl0.9Br0.1 served as the CO2-reduction photocatalyst, surface-treated WO3 as the H2O-oxidation photocatalyst, and I−/IO3− as the redox mediator. The CoOx−Ag dual cocatalysts play distinct yet cooperative roles in the Z-scheme architecture. CoOx preferentially extracts photogenerated holes and accelerates mediator oxidation, thereby promoting charge separation in Bi4TaO8Cl0.9Br0.1 and facilitating inter-photocatalyst charge transfer, whereas Ag acts as an electron-enrichment center that enhances CO2 adsorption and activation and promotes the formation of the key *COOH intermediate for selective CO production. Owing to this synergistic regulation of charge transfer and surface reaction kinetics, the optimized Z-scheme system achieved selective CO2 reduction to CO with near 100% selectivity and synchronous O2 evolution in a near-stoichiometric ratio relative to CO under visible-light irradiation. This work offers a dual-cocatalyst design strategy for efficient visible-light-driven Z-scheme CO2 reduction coupled with H2O oxidation.
✓ 已验证
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Anqi Li,Xiaoyu Qian,Mengyan Han,Zhichun Li,Xiaobo He,Guofeng Wang
Electrochemical catalytic water splitting is considered as a promising technique for green hydrogen production, and highly active catalysts toward cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) are required, especially bifunctional ones. In this work, the bifunctional catalysts with Co-CoO x @N, O co-doped carbon (NOC) hybrid nanostructures have been prepared via pyrolysis of ZIF-Co with assistance of a small amount of KNO 3 . KNO 3 plays important roles in tuning the inner and the outer structures of Co-CoO x @NOC hybrid nanostructures. The proposed S Ov , which is defined as the content of oxygen vacancy (O v ) per unit surface area of the inner Co-CoO x nanoparticle, and charge transfer resistance ( R ct ) are used as the descriptors of the inner structures, while hydrophilicity (or contact angle) is applied as the main feature of the outer structures. S Ov , R ct and hydrophilicity are well tuned by the fed mass of KNO 3 , and a moderate fed mass is the key to balancing S Ov , R ct and hydrophilicity and further is beneficial to accelerating specific and intrinsic activity for both HER and OER . Thus, the bifunctional HER/OER specific and intrinsic activity is peaked by Co-CoO x @NOC-0.025KNO 3 with a moderate fed mass of KNO 3 of 0.025 g, such as j s-250-HER of 539.22 μA cm -2 BET and j s-350-OER of 129.83 μA cm -2 BET at the HER and OER overpotentials of 250 and 350 mV, respectively, also corresponding to high turnover frequencies of 6.653 and 0.801 s −1 , respectively. The optimal catalyst also has high apparent activity, such as achieving high HER and OER current densities of 500 mA cm −2 , only requiring low overpotentials of 273.1 and 382 mV, respectively. It promotes overall water splitting with a high current density of 500 mA cm −2 at a cell voltage of ∼ 1.63 V, showing the high HER and OER Faradaic efficiencies of ∼ 98.2 and ∼ 98.0 %, respectively.
研究领域:
材料科学
·
电化学
·
催化科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Rosine Ahishakiye,Fumin Wang,Xubin Zhang,Mingshuai Sun,Yi Zhai,Yongkui Liu,Yuzhou Wu,Mengyue Li,Mengyao Li,Qing Zhang
The efficient production of the liquid fuel 2,5-dimethylfuran (DMF) from biomass-derived 5-hydroxymethylfurfural (HMF) is very complicated because of the presence of the aldehyde group, hydroxyl group, and C C bond. In this study, a novel Co-CoOx –FeNiCo/γ-Al 2 O 3 catalyst was developed for selective hydrogenation of HMF to DMF. The catalyst was characterized by using XRD, TEM , SAED , BET, XPS, NH 3 -TPD, and H 2 -TPR techniques. The catalyst reduced at 500 °C exhibited excellent catalytic performance and the highest DMF yield (>99.9%) was obtained at 190 °C and 4 h. During the reaction, metal sites selectively hydrogenated the C O bond while acid sites (CoOx acid sites) selectively hydrogenolyzed C O bond. Appropriate surface acidity of the catalyst and the balance between metal and metal oxide species are the main factors for achieving a high yield of DMF. At reaction temperatures below 150 °C, DMF was not produced and HMF has completely converted into 2,5-Bis(hydroxymethyl)furan (BHMF), an important furan diol for polymers production. 100% BHMF yield was also obtained for the HMF hydrogenation over 300 °C reduced catalysts due to the high concentration of strong acid sites. The catalyst recyclability exhibited excellent stability and the original activity was maintained after six reuses. A reaction mechanism was also proposed.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2020
·Vol. 31
·期 9
·2009610
·
IF 16.836
Yong Yan,Chunyue Liu,Hanwen Jian,Xing Cheng,Ting Hu,Dong Wang,Lu Shang,Ge Chen,Peter Schaaf,Xiayan Wang,Erjun Kan,Tierui Zhang
The development of economical, highly active, and robust electrocatalysts for oxygen evolution reaction (OER) is one of the major obstacles for producing affordable water splitting systems and metal-air batteries. Herein, it is reported that the subnanometric CoO x clusters with high oxidation state substitutionally dispersed in the lattice of rutile TiO 2 support (Co-TiO 2 ) can be prepared by a thermally induced phase segregation process. Owing to the strong interaction of CoO x clusters and TiO 2 support, Co-TiO 2 exhibits both excellent intrinsic activity and durability for OER. The turnover frequency of Co-TiO 2 is up to 3.250 s −1 at overpotentials of 350 mV; this value is one of the highest in terms of OER performance among the current Co-based active materials under similar testing conditions; moreover, the OER current density loss is only 6.5% at a constant overpotential of 400 mV for 30 000 s, which is superior to the benchmark Co 3 O 4 and RuO 2 catalysts. Mechanism analysis demonstrates that charge transfer occurs between Co sites and their neighboring Ti atoms, triggering the efficient Co Ti cooperative catalytic centers, in which OH* and O* are preferred to be adsorbed on the bridging sites of Co and Ti with favorable adsorption energy, inducing a lower energy barrier for O 2 generation.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
·
IF 3.218
Yunshu Zhang,Dandan Wang,Xiaolin Wang,Fuming Chen
The electro-synthesis of hydrogen peroxide (H 2 O 2 ) through the two-electron oxygen reduction reaction (ORR) is an inexpensive and environmentally friendly process. In this study, as catalysts for the ORR, two kinds of activated carbon (AC) with different mesopore size distributions are modified by nitrogen (N)-doping and cobalt oxide (CoO x )-loading treatment. It can be concluded that pyridinic-N and pyrrolic-N (48.94%) are more easily formed on the AC with narrow mesopore size distributions (AC-1, 2–5 nm), however, graphite-N (63.9%) are more easily formed on the AC with broad mesopore size distributions (AC-2, 5–15 nm). Furthermore, Co 3 O 4 and CoO is the predominant crystal loaded onto the modified AC-1 and modified AC-2, respectively. The modified AC-1 has an extremely high propensity for a four-electron ORR pathway, while the modified AC-2 has an extremely high propensity for a two-electron ORR pathway. In addition, a rolling activated carbon electrode (RACE) with low-cost and high-efficiency is fabricated by modified AC-2. The H 2 O 2 electro-synthesis rate and current efficiency for the RACE are 0.236 ± 0.025 mg/h/mA/cm 2 and 63.25 ± 6.79%, respectively.
研究领域:
材料科学
·
电化学
✓ 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）