CRYSTENGCOMM
·
2021
·Vol. 23
·期 28
·4930-4937
·
IF 3.545
Wenhan Zhou,Yang Li,Lingcheng Zheng,Jun Liu,Ranran Tang,Kejian Shi,Yanyan Zhang
Considering their actual commercial large-scale applications, research on non-precious metal catalysts has garnered much interest. Particularly, metal–organic frameworks (MOFs) are used as non-precious metal catalysts because of their controllable, high surface area and rich N content. Herein, a MOF is transformed into a three-dimensional and porous Co–N–C catalyst by a one-step synthesis method and the joint action of Zn and PVP is reported. The catalyst exhibited efficient oxygen reduction reaction (ORR) performance (E1/2 = 0.83 V vs. RHE) and oxygen evolution reaction (OER) performance (Ej10 = 1.69 V vs. RHE). More meaningfully, the Zn–air battery (ZAB) assembled with the catalyst, exhibited superior 3100 min cycling charging/discharging stability and a high power density of 109.8 mW cm−2, compared with the Pt–RuO2 of 2600 min of cycling charging/discharging stability and power density of 96.1 mW cm−2. The solid-state ZAB based on the catalyst also showed excellent rechargeable flexibility and stability. Undoubtedly, this is a bifunctional oxygen electrocatalytic catalyst with practical application value.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Xiaowu Liang,Pengfei Wang,Congli Li,Min Yuan,Qi Shi,Jinxiang Dong
CO is an important raw material and the separation of CO/N 2 in blast furnace gas can supply an abundant source of CO. Metal organic frameworks (MOFs) containing open metal sites are capable of selectively binding to CO over N 2 . However, the open metal sites easily bind to guest molecules during the preparation and activation process. In this study, typical MOFs containing open metal sites (Co-MOF-74) were used to investigate the activation behavior and corresponding CO/N 2 adsorptive separation performance. To characterize the removal and decomposition of guest molecules, TG-MS and NMR analysis of MOF-74 prepared under different activation conditions were performed. During the heat and vacuum process, the guest H 2 O and methanol (MeOH) molecules in Co-MOF-74 were first removed at 150 °C under vacuum. The aim of high temperature activation at 300 °C is the decomposition of a small amount of bind N,N-dimethylformamide (DMF) and terminal ligands occupying the open metal sites in Co-MOF-74. In addition, H 2 O molecules occupy the open metal sites of Co-MOF-74 during the filtration and MeOH wash steps under air, which is accompanied by the removal of a portion of DMF. The CO adsorption (298 K and 1 bar) and the CO/N 2 selectivity (Ideal adsorbed solution theory: 50:50, v/v) of Co-MOF-74 activated at 300 °C was 6.07 mmol/g and 384, respectively, which was higher than that of the other activated Co-MOF-74 samples and was attributed to the effective removal of guest molecules. Our results may guide the activation of MOFs, which contain open metal sites.
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ACS ES&T Engineering
·
2020
·
IF 0
Yuxian Wang,Nuo Ren,Jiaxin Xi,Ya Liu,Tao Kong,Chunmao Chen,Yongbing Xie,Xiaoguang Duan,Shaobin Wang
High-performance and robust catalysts act as core drivers for advanced oxidation technologies for decontamination of water resources. In this study, we used a facile strategy to prepare magnetic and N-doped carbon nanotubes with cobalt encapsulation (Co–N@CNTs) to catalyze ozone for decomposition of aqueous organic pollutants. By regulating the thermal conditions during the synthesis, the derived Co–N@CNTs manifested maneuvered adsorption capabilities. The embedded Co nanoparticles (NPs) not only afforded carbon nanotubes with a magnetic property but also significantly boosted catalytic ozonation due to the synergistic coupling of the Co interface and N-doped graphitic layer. Formation of such a coordinating structure accelerated electron transfer at the interface and increased the conductivity of surface carbon to coordinate a redox reaction. Density functional theory (DFT) calculations and experimental evidence confirmed that cobalt coupled with graphene with pyridinic N dopants was the most favorable structure, which remarkably enhanced ozone adsorption and its dissociation to generate reactive oxygen species (ROS). Intriguingly, the catalytic ozonation underwent different nonradical regimes dependent on the molecular structures of target organics. In terms of ROS, surface-adsorbed atomic oxygen (*Oad) was responsible for degradation of oxalic acid, while phenolics were primarily degraded by O3 molecules and singlet oxygen (1O2). This study provides a cost-efficient and recyclable carbocatalyst for wastewater decontamination and new insights into the structure–functional relationships in carbon-based advanced oxidation processes.
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Processes
·
2021
·Vol. 9
·期 2
·230
·
IF 2.847
Peng Peng,Jun Li,Shengpeng Mo,Qi Zhang,Taiming Shen,Qinglin Xie
Carbon monoxide (CO) and hydrocarbons (HCs) generally have competitive adsorption on the active site of noble-metal nano-catalysts, thus developing an effective way to reduce the passivation of competitive reaction with each other is an urgent problem. In this study, we successfully synthesized transition metal-noble metal (Pt-M) alloys via introducing inexpensive metal elements (M = Ni, Co and Cu) into Pt particles and then deposited on alumina support to form Pt-based catalysts. Subsequently, we choose CO and toluene as polluting gases to evaluate the catalytic activities of Pt-M/Al2O3catalysts. Introducing inexpensive metal elements (M = Ni, Co, and Cu) significantly changed the physicochemical properties and catalytic activities of these Pt-based catalysts. It can be found that the Pt-Co/Al2O3catalyst exhibited outstanding catalytic activity for CO and toluene oxidation under mixed gas atmosphere, compared with other Pt-based catalysts, which is due to the higher dispersity, more surface adsorption oxygen, and well redox ability. Surprisingly, H2O could promote the catalytic activities for CO/toluene co-oxidation over the Pt-Co/Al2O3catalyst. Thus, the present synthetic strategy not only opens an avenue towards the synthesis of noble metal-based catalysts, but also provides an excellent tolerance to H2O in the catalytic process.Keywords:bimetallic alloy;Pt-based catalysts;catalytic oxidation;toluene;moisture
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Nanomaterials
·
2020
·Vol. 10
·期 6
·1035
·
IF 4.324
Xiang Nie,Guo Li,Zhao Jiang,Wei Li,Ting Ouyang,Jianfeng Wang
Exfoliation of two-dimensional boron nitride nanosheets (BNNSs) from parent bulk material has been receiving intensive attention because of its fascinating physical properties. Liquid exfoliation is a simple, scalable approach to produce single-layer or few-layer BNNS. In this paper, water/propanol co-solvent exfoliation of bulk boron nitride under the assistance of sonication was investigated in detail. Special attention was paid on the effect of raw bulk boron nitride size and co-solvent composition. The results show that sonication of small-size hexagonal boron nitride tends to generate large nanosheets, due to a predominant solvent wedge effect. In addition, it is found that the composition of water/propanol co-solvent has an important effect on exfoliation efficiency. Interestingly, although two isomers of 1-propanol (NPA) and 2-propanol (IPA) have the same molecular weight and similar surface tension, their aqueous solutions allow the formation of boron nitride nanosheets dispersion with markedly different concentrations. It is proposed that due to their spatial configuration difference, NPA with its longer molecular chain and fewer hydrophobic methyl group tends to form dynamic water-NPA clusters with larger size than water-IPA clusters. The hydrodynamic radius of the co-solvent “clusters” was calculated to be 0.72 nm for water/NPA system and 0.44 nm for water/IPA system at their maximum, respectively. Their size changes, represented by two curves, indicate a strong “cluster size” effect on exfoliation efficiency. Our work provides an insight into co-solvent exfoliation of hexagonal boron nitride and emphasizes the importance of co-solvent cluster size in exfoliation efficiency.Keywords:liquid phase exfoliation;boron nitride nanosheets;co-solvent cluster;size effect
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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Weiyi Chen,Bin Han,Yili Xie,Shujie Liang,Hong Deng,Zhang Lin
Converting carbon dioxide (CO 2 ) to multiple energy-rich chemicals by photocatalysis could validly mitigate the severe issues of climate changes and energy shortages. Exploring efficient catalysts for enhancing the performance of CO 2 photoreduction is still challenging. Herein, a novel three-dimensional hierarchical Co-Co layered double hydroxide/Ti 3 C 2 T X nanosheets (Co-Co LDH/TNS) nanoarray was successfully prepared via an in-situ MOF-derived strategy. This wise design rationally integrates the functional and structural merits of active Co species with conductive MXene to a hierarchical nanoarray architecture composed of ultrathin nanosheets, which can remarkably promote separation of photogenerated charge carriers and accelerate electrons transmission. Benefitting from these features, the hierarchical Co-Co LDH/TNS composites manifest significant enhancement on the CO 2 -to-CO evolving rate (1.25 × 10 4 µmol h −1 g −1 ) under illumination (>400 nm) with a high apparent quantum efficiency (0.92%) and excellent stability. Our work demonstrates that 3D hybrid structure composed of MXene species can serve as promising candidates for CO 2 photoreduction, providing fundamental guidance to improve photocatalytic performance by rational engineering of complex hierarchical architecture materials.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2023
·
IF 7.2
Guoliang Gao,Dongwei Wei,Li Li,MingQi Wei,Xueli Chen,Yangyang Yu,Guang Yang,Guang Zhu,Lu Han,Jin Jia
Transition metal phosphates have proved to be promising electrocatalysts for hydrogen evolution reactions (HER) of water splitting, however, further increasing their active sites and catalytic activity remains a major challenge. Herein, accordion-like Co-MOF with layered structure was synthesized. After subsequent carbonization and phosphidization, lamellar heterostructured Co/CoP nanocrystals encapsulated in a P, N co-doped C matrix (Co/CoP@PNC) was obtained. Heterojunction provides abundant active sites and improves electron transfer rate. Additionally, the effect of phosphating degree on the electrocatalytic activity was studied. In the alkaline electrolyte , the current density of the optimized Co/CoP@PNC-10 for HER reached 10 mA cm −2 at overpotential of 137 mV in 1.0 M KOH, which was superior to most of transition metal-based electrocatalysts. This work provides new guidance for the design and development of transition metal-based electrocatalysts.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Xinyang Wang,Rui Li,Xinyu Luo,Jincheng Mu,Jianbiao Peng,Guangxuan Yan,Pengkun Wei,Zhenbang Tian,Zuohua Huang,Zhiguo Cao
Enhancing low-temperature activity is a focus for carbon monoxide (CO) elimination by catalytic oxidation. In this work, the hierarchical flower-like silver (Ag) modified cobalt oxides (Co 3 O 4 ) nanosheets were prepared by solvothermal method and applied into catalytic CO oxidation. The doped Ag species in the form of AgCoO 2 induced the prolongated surface Co–O bond and weaker bond intensity. Consequently, the oxygen activation/migration ability and redox capacity of Ag 0.02 Co were enhanced with more oxygen vacancies. The chemisorbed CO was preferentially converted to CO 2 but not carbonates. The inhibited carbonates accumulation could avoid the coverage of active sites. According to Density functional theory (DFT) calculations, the electron transfer from AgCoO 2 to Co 3 O 4 promote electron donation ability of Co 3 O 4 layer, benefiting for oxygen activation. Moreover, the longer Co–C and C–O bond length suggest the weakened chemisorption strength and higher active of CO molecule. The Ag modified Co 3 O 4 exhibited more satisfactory activity at lower temperature. Typically, it realized 100% CO conversion at 90 °C, and displayed 6.3-fold higher reaction rate than pristine Co 3 O 4 at 40 °C. Moreover, the Ag 0.02 Co exhibited outstanding long-term stability and water resistance. In summary, the optimized oxygen activation, CO chemisorption and interfacial electron transfer synergistically boosted the CO oxidation activity on Ag modified Co 3 O 4 .
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Lin Tan,Jing Han,Chuanwen Wang,Genwang Zhang,Huixia Feng,Nali Chen,Dan Zhao
Due to their physicochemical properties, the three-dimensional Metal-organic frameworks (MOFs) derived composites show great potential as electromagnetic wave (EMW) absorbers. However, poor impedance matching limits their actual EMW absorption performance. Composite materials that combine magnetic and dielectric losses offer a potential solution to enhance impedance match and significantly improve microwave absorption. In this work, a novel N,S-GS/Co/C composite was fabricated via a solvothermal method and a subsequent pyrolysis process to introducing nitrogen and sulfur co-doped graphene (N,S-GS) into Co-MOF. By co-doping nitrogen and sulfur, abundant defects and disordered sites were introduced on graphene, which stimulate interfacial polarization and dipole polarization. The minimum reflection loss (RL) of the sample obtained by pyrolysis at 600 °C is −68.8 dB at 9.7 GHz. Simultaneously, the thickness is 2.51 mm, and the effective absorption bandwidth (EAB) can reach 3.04 GHz. Its excellent EMW absorption performance is mainly attributed to interfacial polarization, multiple reflections, dipole polarization, magnetic resonance and eddy current loss. Accordingly, the N,S-GS/Co/C composite is convinced to be a competent candidate among EMW absorbers with high absorption intensity.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2023
·
IF 8.4
Cong Qin,Zhanxiang Wei,Bing Wang,Yingde Wang
In the realm of gas sensors, p-type metal oxide semiconductor (MOS) usually exhibits inherently low sensitivity toward target gases caused by the hole accumulation layer configuration , which seriously hinders its practical application. Diatomics co-doping is an efficient tactic for adjusting the characteristics of MOS related to gas-sensing due to their synergistic effect . In this work, we controllably synthesized bare Co 3 O 4 , Sn-doped Co 3 O 4 , Mn-doped Co 3 O 4 and Sn/Mn co-doped Co 3 O 4 nanosheets . The experimental results reveal that Sn/Mn co-doped Co 3 O 4 sample presents porous nanosheets structure. 1 mol% Sn/Mn co-doped Co 3 O 4 sensor presents enhanced response [(R g -R a )/R a = 330 %∼40 ppm at 150 °C] toward CO compared with the bare Co 3 O 4 , 1 mol% Sn-doped Co 3 O 4 , and 1 mol% Mn-doped Co 3 O 4 nanosheets. Besides, 1 mol% Sn/Mn co-doped Co 3 O 4 nanosheets show a low limit of detection (500 ppb/experimental value), good stability and selectivity. We infer that the good CO-sensing properties may be ascribed to the oxygen vacancies defects generated by Sn 4+ and Mn 2+ /Mn 3+ co-doping, high Co 3+ ratio, and high specific surface area. This study affords an effective co-doping strategy for enhancing the gas-sensing performances of p-type MOS.
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DALTON TRANSACTIONS
·
2023
·Vol. 52
·期 23
·7869-7875
·
IF 4
Deling Wang,Lu Chen,Yuzhou Xia,Ruowen Liang,Xiyao Liu,Shaoming Ying,Guiyang Yan
Developing novel photocatalysts with an intimate interface and sufficient contact is significant for the separation and migration of photogenerated carriers. In this work, a novel Co@NC/ZnIn2S4 heterojunction with a strong Co–S chemical bond was formed at the interface between Co@NC and ZnIn2S4, which accelerated charge separation. Meanwhile, the recombination of the electron–hole pairs was further restricted by the Co@NC/ZnIn2S4 Schottky junction. The Co@NC (5 wt%)/ZnIn2S4 composite exhibited an H2 evolution rate of 33.3 μmol h−1, which is 6.1 times higher than that of the pristine ZnIn2S4, and Co@NC/ZnIn2S4 showed excellent stability in the photocatalytic water splitting reaction. Its apparent quantum yield reached 38% at 420 nm. Furthermore, the Kelvin probe test results showed that the interfacial electric field formed as the driving force for interface charge transfer was oriented from Co@NC to ZnIn2S4. In addition, the Co–S bond as a high-speed channel facilitated the interfacial electron transfer. This work reveals that in situ formed chemical bonds will pave the way for designing high-efficiency heterojunction photocatalysts.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 15
·1-12
·
IF 2.8
Pan Yusong,Zhu Yuan,Wang Yuanqing,Huang Run,Pan Chengling
Based on the strong capability of transition metal ions for peroxymonosulfate (PMS) activation and highly affinity of MoS 2 towards PMS, thus decorating MoS 2 with transition metal ions would efficiently activate PMS for degradation of organic pollutants. In this work, Co/Fe co-doped MoS 2 catalyst were synthesized by simple chemical method. The prepared Co/Fe co-doped MoS 2 catalyst displayed excellent catalytic activity for organic pollutant degradation. The removal efficiency of RhB and MB is 99% in 6 min and 98% in 15 min under PMS system, respectively. Both the capture experiment and EPR results verified that 1 O 2 played an important role in the organic pollutant degradation process in PMS system. The catalytic mechanism revealed that the synergistic effect between Mo ion and Co/Fe ions is beneficial for boosting the catalytic properties of Co/Fe co-doped MoS 2 catalyst. The cycle experiments confirmed that Co/Fe co-doped MoS 2 possesses excellent chemical stability and re-usability.
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