Nature Communications
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2021
·Vol. 12
·期 1
·1-10
·
IF 14.919
Sayed Mahmoud,Xu Feiyan,Kuang Panyong,Low Jingxiang,Wang Shengyao,Zhang Liuyang,Yu Jiaguo
Solar conversion of CO 2 into energy-rich products is one of the sustainable solutions to lessen the global energy shortage and environmental crisis. Pitifully, it is still challenging to attain reliable and affordable CO 2 conversion. Herein, we demonstrate a facile one-pot approach to design core-triple shell Mn, C-codoped ZnO hollow spheres as efficient photocatalysts for CO 2 reduction. The Mn ions, with switchable valence states, function as “ionized cocatalyst” to promote the CO 2 adsorption and light harvesting of the system. Besides, they can capture photogenerated electrons from the conduction band of ZnO and provide the electrons for CO 2 reduction. This process is continuous due to the switchable valence states of Mn ions. Benefiting from such unique features, the prepared photocatalysts demonstrated fairly good CO 2 conversion performance. This work is endeavoured to shed light on the role of ionized cocatalyst towards sustainable energy production.
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CHEMOSPHERE
·
2021
·
IF 7.086
Jian Cheng,Yirui Xie,Ying Wei,Dongrun Xie,Wenbo Sun,Ying Zhang,Menghong Li,Jiutao An
Dielectric barrier discharge (DBD) plasma coupled with Fe–Mn doped AC (Fe–Mn/AC) was used to enhance the degradation of tetracycline hydrochloride (TCH) wastewater. Fe–Mn/AC catalysts with different Fe/Mn molar ratios were prepared by hydrothermal method, and the physical and chemical properties of the samples were explored by different characterization techniques, including XRD, SEM , TEM and XPS. The results showed that the combination of DBD with Fe 2 –Mn 1 /AC system had the highest effect, and the degradation efficiency of TCH could reach 98.8 % after 15 min treatment, which was 25.5 % higher than that of DBD-only. With the increase of discharge voltage and catalyst dosage, the degradation efficiency of TCH promoted. And initial pH had little effect on the degradation of TCH. In the combined system, the Fe 2 –Mn 1 /AC catalyst could retain an excellent stability and reusability. The addition of dimethyl sulfoxide (DMSO) showed that ·OH participated in the TCH degradation. The generated O 3 might be catalyzed by Fe–Mn/AC catalyst to produce more ·OH. And more H 2 O 2 was produced in DBD-only system than that in DBD-catalytic system. Nine main degradation intermediate products in the combined system were detected by HPLC-MS, and three possible degradation pathways were proposed.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2021
·
IF 8.128
Yueyue He,Shuo Wang,Haiyan Zhang,Xin Chen,Jin Li,Huiyuan Xu,Yanhui Zhang,KangHui Hu,Genpin Lv,Yan Meng,Wei Xiang
Li-rich disordered rock-salt cathode (DRX) materials with advantage of low cost, long cycle life, nature abundant resource and high power and energy density attracted a great deal of scholarly attention. However, the poor cycle stability and the unclear realization of cation and anion redox activity in low-cost element system have severely hindered the construction of high-performance DRX. Herein, a promising class of Ti-Mn based cathode materials Li 1.25 Mn 0.25 Nb 0.25 Ti 0.25 O 2 and Li 1.25 Mn 0.25 Ti 0.5 O 1.75 F 0.25 were designed and successfully synthesized to construct high energy density DRX and investigate the effect of fluorination on cation and anion redox activity. The results show that both fluoridized and unfluoridized DRX possess a similar structure ( Fm -3 m), but distinctly different charge/discharge profiles. The fluoridized cathode shows high initial charge/discharge capacity of 317.3/283.9 mAh g −1 , specific energy density of 1370.4/735.5 Wh kg −1 and stable capacity retention with a discharge capacity of 202.6 mAh g −1 after 20 cycles at 20 mA g −1 . Combining relevant spectroscopic results and HRTEM images, we revealed that the excellent cyclability of Li 1.25 Mn 0.25 Ti 0.5 O 1.75 F 0.25 is rooted in the weakened adverse effects of moderated oxygen redox and the reduced Jahn–Teller distortion effect resulting from Mn 3+ , endowing the fluoridized DRX with better structural stability and larger Mn 2+ /Mn 4+ reservoir. The strategy of constructing low cost oxyfluoride and the understanding of the mechanism of fluorination induced cation and anion redox activity would provide reference for the development of high-performance DRX materials.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2021
·
IF 3.171
Fu Yang,Ruyi Wang,Shijian Zhou,Xuyu Wang,Yan Kong,Shuying Gao
The oxidative desulphurization (ODS) has become mainly popular by rapid catalytic oxidation of dibenzothiophene (DBT) relied on efficient heterogeneous catalyst. V-based catalytic active species were regarded as the potential option in the activity-preferred ODS systems. Herein, we reported the re-dispersion of vanadium oxide (VO x ) on the mesoporous silica modified with manganese oxide (Mn 3 O 4 ) through one progressive insertion approach of metal oxides in the silica. Impressively, mesopore-encaged vanadium-manganese oxides in the silica (VMn-MS) as the admirable output of excellent ODS catalyst was demonstrated compared to other monometal-modified counterparts and one-pot implanted one. The characterization results revealed the post-implanted VO x species not only deposited around the pre-covered Mn 3 O 4 on the mesoporous surface but also inserted the surface layer of Mn 3 O 4 inducing the amorphous evolution of aggregated Mn 3 O 4 and the reconstruction of final active sites. This integrated approach made the reconstructed active species afford more exposed catalytic sites and the tailored surface redox cycles owing to the electronic communication of V-Mn. The catalytic results demonstrated the excellent catalytic desulphurization efficiency (~100%) during 60 min at 80 °C, which made the sulphur content reduce to 6 mg·L −1 , remarkably superior to other comparative samples. The outstanding catalytic performance of VMn-MS catalyst can be ascribed to the synergistic effect of V-Mn dual metals rendering two different reaction pathways, which includes free-radical reaction and ring-forming reaction, where Mn site acted as active center triggering reactive free radicals which could be further optimized by surrounded V sites around Mn sites to promote the ODS process.
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CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Xuqian Wang,Yi Xie,Kun Chen,Likexin Yi,Yabo Wang,Yongkui Zhang
Ferruginous rhodochrosite with high impurity is difficult to be utilized by traditional beneficiation process due to the complex characteristics. Herein, a bioleaching process driven by Acidithiobacillus ferrooxidans was proposed to recover Mn and Fe in ferruginous rhodochrosite with economic and environmental benefits. The biogenic Fe 3+ , H + and extracellular polymeric substances produced in bioleaching process significantly promoted the metal recovery and reduced the H 2 S emission. Optimal metal leaching efficiencies (95.94% of Mn and 97.54% of Fe) were achieved in bioleaching group. Furthermore, the Mn and Fe mixed leaching solutions could be directly adopted to fabricate Mn-Fe oxide based materials (MFO). When applied as catalysts for peroxymonosulfate (PMS) activation, the as-synthesized MFO performed well for sulfathiazole (STZ) degradation with a 98.66% removal efficiency in 40 min. Both radical process and non-radical process occurred in the advanced oxidation process, which induced the generation of abundant active species of ̇OH, SO 4 ̇ − and 1 O 2 . Meanwhile, charge transfer also contributed to STZ degradation. Favorably, MFO-3 exhibited good reusability in recycle study and showed adaptability towards various natural water matrixes. This research not only provided novel insights into the utilization of recalcitrant ferruginous rhodochrosite resources, but also enriched the strategy of PMS activator design for environmental remediation.
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Catalysis Science & Technology
·
2021
·Vol. 11
·期 7
·2577-2588
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IF 6.119
Xian Wu,Weixin Qian,Haitao Zhang,Zhonghao Han,Hewei Zhang,Hongfang Ma,Dianhua Liu,Qiwen Sun,Weiyong Ying
CeO2 nanorods with a mean width of 11.9 nm were synthesized via a facile hydrothermal method. Subsequently, Fe/CeO2 and Fe/CeO2@xMnO2 catalysts were prepared from the CeO2 nanorods and applied in the high-temperature Fischer–Tropsch synthesis of light olefins. Results show that the CeO2 support donates electrons to Fe species, which promotes the dissociation of CO while suppressing the hydrogenation reaction, and then improves the selectivity to light olefins. The synergistic effect between Mn and Ce can improve the oxygen mobility on the catalyst surface and promote the electron-donating ability of Ce, thereby promoting the formation of χ-Fe5C2 and further improving the selectivity to light olefins. However, excess Mn hinders the contact between CeO2 and Fe species and the migration of O atoms, and electron transfer from Ce to Fe can be blocked. Additionally, the reduction of iron oxides was suppressed and subsequently the CO conversion was reduced. The best hydrocarbon distribution for light olefins was 40.4% at a CO conversion of 39.9% over the Fe/CeO2@0.2MnO2 catalyst.
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Catalysis Science & Technology
·
2020
·Vol. 10
·期 6
·1941-1951
·
IF 5.721
Shaohua Chen,Hui Li,Yu Hao,Rui Chen,Tiehong Chen
A series of porous Mn-based oxides (mullite SmMn2O5, perovskite SmMnO3, spinel Mn3O4 and bixbyite Mn2O3) were systematically prepared and applied in ethanol and toluene catalytic oxidation. Among them, SmMn2O5 exhibited the highest catalytic activity, the best hydrothermal stability and the highest durability. Due to the different compositions and structures of the catalysts, the surface composition, Mn-valence state, reduction properties, and adsorption and desorption behavior of oxygen and ethanol were different as characterized by XPS, H2-TPR, O2-TPD and ethanol-TPD measurements. Based on the characterization results, the relationship between the catalyst structure (crystal and electronic structure) and catalytic activity was discussed in terms of their crystal field configurations and structures of the energy bands. The superior activity of SmMn2O5 could be attributed to dz2 orbital occupancy near the Fermi level determined by the Mn3+-centered pyramidal field, as well as the existence of a Mn3+–Mn3+ dimeric structure, which is critical for C–C bond cleavage.
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CHEMICAL ENGINEERING JOURNAL
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2020
·
IF 10.652
Kun Wu,Meng Wang,Angzhen Li,Zixuan Zhao,Ting Liu,Xiaodan Hao,Shengjiong Yang,Pengkang Jin
Mn-oxide-containing adsorbents have shown outstanding performances for the removal of As(III) through an “oxidation-adsorption” process. In this study, a new adsorbent of Fe-Mn-Cu ternary oxide (FMCTO) was fabricated to improve the redox reaction rate and to enhance the recovery of oxidative ability. FMCTO exhibited a stronger ability for As(III) removal than most of other adsorbents, because it has better oxidative capability for As(III) oxidation. The state of dynamic equilibrium for As(III) removal by FMCTO could be basically achieved within 3 h, and the As removal efficiency reached 98.9% at time = 24 h. The Langmuir As adsorption capacity of FMCTO was determined to be 204.8 mg/g. The As(III) removal efficiency of FMCTO was further boosted by 7% through oxygen gas aeration and decreased by 19% with nitrogen gas in the ambient during the first 3 h, indicating the positive effect of oxygen on As(III) oxidation. EPR and UV spectra methods were used to confirm the generation of superoxide radical (O 2 − ) and the enhanced production of Mn(III) soluble species on FMCTO surfaces, thus achieving a better As(III) oxidation performance. The XPS analysis results showed that the electron transfer from Cu(I) to Mn(IV) could improve the stability of Mn(III) within FMCTO. Meanwhile, Mn(II) ions could be oxidized to Mn(III) by O 2 − . Hence, the formation of a redox cycle between Mn(II) and Mn(III) along with the production of O 2 − plays a vital role in the upgraded As(III) removal mechanisms. This study provides new insights into the promotion of the capability of Mn-containing adsorbents for achieving the improved removal of As from As(III)-contaminated water.
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Journal of Energy Chemistry
·
2020
·
IF 7.216
Jia Sun,Lei Du,Baoyu Sun,Guokang Han,Yulin Ma,Jiajun Wang,Hua Huo,Pengjian Zuo,Chunyu Du,Geping Yin
ABO 3 -type perovskite oxides (e.g., LaCoO 3 ) with flexible and adjustable A- and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity (e.g., oxygen reduction/evolution reactions, ORR/OER). It has been well understood in our recent work that the secondary metal dopant at B-site (e.g., Mn in LaMn x Co 1 −x O 3 ) can regulate the electronic structure and improve the ORR/OER activity. In this work, the Mn-Ni pairs are employed as the dual dopant in LaMn x Ni y Co z O 3 ( x + y + z = 1) catalysts toward bifunctional ORR and OER. The structure–property relationships between the triple metal B-site (Mn, Ni and Co) and the electrochemical performance are particularly investigated. Compared to the individual Mn doping (e.g., LaMnCoO 3 (Mn:Co = 1:3) catalyst), the dual Mn-Ni doping significantly improves the ORR mass activity@0.8 V by 1.54 times; meanwhile, the OER overpotential@10 mA cm −2 is reduced from 420 to 370 mV, and the OER current density at 1.55 V is increased by 2.43 times. Reasonably, the potential gap between E ORR @-1 mA cm −2 and E OER @10 mA cm −2 is achieved as only 0.76 V by using the optimal LaMn x Ni y Co z O 3 ( x : y : z = 1:2:3) catalyst. It is revealed that the dual Mn-Ni dopant efficiently optimizes electron structures of the LaMnNiCoO 3 (1:2:3) catalyst, which not only decreases the e g orbital electron number, but also modulates the O 2p-band closer to the Femi level, accounting for the enhanced bifunctional activity.
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DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 20
·6718-6729
·
IF 4.174
To Van Nguyen,Le The Son,Vu Van Thuy,Vu Dinh Thao,Masahito Hatsukano,Koichi Higashimine,Shinya Maenosono,Sang-Eun Chun,Tran Viet Thu
We report the synthesis of manganese-doped nickel cobalt oxide (Mn-doped NiCo2O4) nanoparticles (NPs) by an efficient hydrothermal and subsequent calcination route. The material exhibits a homogeneous distribution of the Mn dopant and a battery-type behavior when tested as a supercapacitor electrode material. Mn-doped NiCo2O4 NPs show an excellent specific capacity of 417 C g−1 at a scan rate of 10 mV s−1 and 204.3 C g−1 at a current density of 1 A g−1 in a standard three-electrode configuration, ca. 152–466% higher than that of pristine NiCo2O4 or MnCo2O4. In addition, Mn-doped NiCo2O4 NPs showed an excellent capacitance retention of 99% after 1000 charge–discharge cycles at a current density of 2 A g−1. The symmetric solid-state supercapacitor device assembled using this material delivered an energy density of 0.87 μW h cm−2 at a power density of 25 μW h cm−2 and 0.39 μW h cm−2 at a high power density of 500 μW h cm−2. The cost-effective synthesis and high electrochemical performance suggest that Mn-doped NiCo2O4 is a promising material for supercapacitors.
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Advances in Materials Science and Engineering
·
2019
·
IF 1.399
Zhuo Yao,Dianli Qu,Yuxiang Guo,Yujing Yang,Hong Huang
Novel catalysts with high activity for the selective catalytic reduction of NO with NH3 (NH3-SCR) at low temperatures are highly demanded. In this study, mixed-node metal-organic frameworks (MOFs), e.g. Mn@CuBTC with controlled Mn composition in Cu3(BTC)2, were fabricated using postsynthetic exchange method and their structural characteristics and catalytic performances for NH3-SCR reaction were assessed. A series of analyses in terms of structure, surface morphology, texture, and chemical state determined that Mn ions were successfully incorporated into the Cu3(BTC)2 crystal lattice as well as adsorbed on the walls of nanopores in the framework. The pore sizes can be finely tuned in the presence of Mn ions in the cages, which significantly suppressed water adsorption. The NH3-SCR activity of Mn@CuBTC exhibited nearly 100% NOx conversion rate in the temperature range (230–260°C). The superior NH3-SCR performance is attributed to the proper pore sizes, reduced water content, and the synergistic effect between manganese and copper ions in the MOF structure, which enhanced NH3 bound to the active Lewis sites.
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RSC Advances
·
2019
·Vol. 9
·期 67
·39315-39322
·
IF 3.049
Chang Liu,Jing Lin,Wei Zhai,Zhikai Wen,Xin He,Mengmeng Yu,Yang Huang,Zhonglu Guo,Chao Yu,Chengchun Tang
Doping metal ions in inorganic halide perovskite (CsPbX3, X = Cl, Br, I) nanocrystals (NCs) endows the NCs with unique optical characteristics, and has thus attracted immense attention. However, controllable synthesis of high-quality doped perovskite NCs with tunable morphology still remains challenging. Here, we report a facile, effective and unified strategy for the controllable synthesis of Mn-doped CsPbCl3 quantum dots (QDs) and nanoplatelets (NPLs) via a single-step solvothermal method. The incorporation of Mn2+ into CsPbCl3 NCs introduces new broad photoluminescence (PL) emission from Mn2+ while maintaining the structure of host CsPbCl3 NCs nearly intact. The PL intensity, emission peak position and size of the NCs can be accurately adjusted by altering the experimental parameters such as Mn-to-Pb feed ratio and reaction time. Especially, by changing the amount of ligands, Mn-doped CsPbCl3 QDs, NPLs or their mixtures can be obtained. Both of the Mn-doped QDs and NPLs exhibit a size-dependent quantum confinement effect, which is confirmed by the relationship between the size of NCs and the exciton emission peaks. The solvothermal reaction condition plays an important role for the precise control of the structure, morphology and PL properties of the Mn-doped NCs. The as-prepared Mn-doped CsPbCl3 NPLs with thickness down to ∼2 nm exhibit a PL quantum yield (PLQY) of more than 22%. This work introduces a new strategy for the controllable synthesis of Mn-doped perovskite NCs, which provides ideas for the in-depth study of the dope-and-grow process and can be extended to approaches of doping other metal ions.
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