INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2023
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IF 7.2
Wei Xia,Xiaoxu Luan,Wei Zhang,Dengfeng Wu
Constructing efficient bifunctional electrocatalysts for both cathode and anode is of great importance for obtaining green hydrogen by water splitting. Herein, sulfuration of hierarchical Mn-doped NiCo LDH heterostructures (Mn–NiCoS 2 /NF) is constructed as a bifunctional electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) via a facile hydrothermal-annealing strategy. Mn–NiCoS 2 /NF shows an overpotential of 310 mV at 50 mA cm −2 for OER and 100 mV at 10 mA cm −2 for HER in 1.0 M KOH. Moreover, only 1.496 V@10 mA cm −2 is required for overall water splitting by using Mn–NiCoS 2 /NF as catalyst dual electrodes in a two-electrode system. The excellent performance of Mn–NiCoS 2 /NF should be attributed to the ameliorative energy barriers of adsorption/desorption for HO − /H 2 O through the modification of electronic structure of NiCo basal plane by Mn-doping and the acceleration of water dissociation steps via rich delocalized electron inside sulfur vacancies . The construction of hierarchical Mn–NiCoS 2 /NF heterostructures provides new prospects and visions into developing efficient-advanced electrocatalysts for overall water splitting.
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LWT-FOOD SCIENCE AND TECHNOLOGY
·
2021
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IF 4.952
Yaru Han,Linpin Luo,Liang Zhang,Yi Kang,Hao Sun,Jie Dan,Jing Sun,Wentao Zhang,Tianli Yue,Jianlong Wang
Nanozymes have become a frontier of research recently and possess broad application prospects in the field of analytical sensing. Herein, a Fe–Mn bimetallic nanozyme (FeMnzyme) was proposed for colorimetric analysis of ascorbic acid (AA). The FeMnzyme, with high specific surface area, consisted of Fe–Mn mixed oxide amorphous core and α-FeOOH nanorod shell characterized by scanning electron microscope (SEM) and Powder X-ray diffraction (XRD). It exhibits typical oxidase-like properties to catalyze oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to generate visible blue oxidized TMB (oxTMB) without exogenous H 2 O 2 . Due to the reducibility of AA to oxTMB, the FeMnzyme/oxTMB system can be employed as a promising colorimetric sensor for quantitative analysis of AA. The method has a good linear concentration range of 8 μmol L −1 to 56 μmol L −1 , and the detection limit is as low as 0.88 μmol L −1 (3σ). Finally, the proposed biosensor has been favorably put into use to determine AA content in kiwi fruit, indicating its reliability for practical application.
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FUEL
·
2023
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IF 7.4
Xin Guo,Zhiyong Ding,Na Kang,Liu Yang,Yuanjiang Wang,Cheng Zhang,Zhaoqiang Li,Tiantian Zhang,Yan Wang,Yu Wang,Hao Qu
The zeolite-based catalyst is a promising option for the selective catalytic reduction (SCR) of nitrogen oxides (NO x ) due to its low toxicity. However, the challenge lies in its low-temperature activity. This study developed a multi-component catalytic system consisting of Ce/Mn/Cu-loaded Beta zeolite to reduce NO x . With fixed contents of Cu and Mn, we investigated the NH 3 -SCR process and the mechanism of action of the rare-earth species (i.e., Ce) in the system. Upon optimization of the content of Ce, the Ce/Mn/Cu-loaded Beta zeolite demonstrated enhanced low-temperature activity compared to samples loaded with Cu or Cu/Mn in the temperature range of 150–250 °C. When Ce was loaded in an appropriate proportion, it regulated the oxidation state of Cu, optimizing active adsorption species for NO and strengthening the strength of Brønsted acid sites in the catalyst. These synergetic effects led to improved NH 3 -SCR catalytic performance. This study can contribute to a better understanding of multiple metal-loaded zeolites in the NH 3 -SCR process and inform future design of Beta-type catalysts.
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JOURNAL OF HAZARDOUS MATERIALS
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2023
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IF 13.6
Mingyi Liu,Hanchun Chen,Pengfei Xiao,Haodong Ji
Copper-manganese composite metal oxides (CuMnO y ) were prepared by hydrolysis-driven oxidation-reduction method and used to activate sulfite to degrade chlortetracycline hydrochloride (CTC) for the first time. The Jahn-Teller ions Mn 3+ and Cu 2+ exist in CuMnO y , which form a solid electric charge transport redox system and ensure the continuous generation of reactive oxygen species (ROS). Through the systematic study of the experimental parameters such as sulfite concentration, catalyst metal molar ratio, catalyst amounts and initial pH, the optimal degradation rate of CTC could reach 91.74% within 10 min and 94.46% after 30 min. The major reactive radicals were determined by radical quenching experiments and electron paramagnetic resonance (EPR) trapping techniques, and it was confirmed that SO 4 •- and •O 2 - played a nonnegligible role in the process of degrading CTC. Density functional theory (DFT) calculations show that higher Fukui indices ( f - and f 0 ) of CTC sites are more vulnerable to free radical attack. CuMnO y has low CTC degradation intermediate toxicity, high catalytic performance, good anti-interference ability, reusability and stability, and possesses decent application potential in the actual water treatment field.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2023
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IF 2.7
Feng Tian,Yu Gao,Anping Wang,Lan Xiang,Qikui Man,Hui Xu,Baogen Shen
Efficient microwave absorbing materials are required to solve electromagnetic interference and electromagnetic pollution problems. It has been known that the electromagnetic wave (EMW) absorption properties of ferrites can be improved by element substitution. In this study, the hexagonal Ba 2 Co 2 Mn x Fe 12- x O 22 ( x = 0.0, 0.4, 0.8, 1.2 and 1.6) ferrites were prepared by the solid-phase sintering method, and the effect of Mn substitution on structural, magnetic and microwave absorption performance were investigated in detail. Due to the impact of lattice distortion caused by doping Mn ions in Ba 2 Co 2 Fe 12 O 22 ferrites, the concentration of oxygen vacancy increases first and then decreases with increasing Mn substitution. The real part of complex dielectric constant ( ε' ) of Ba 2 Co 2 Mn x Fe 12- x O 22 ferrites decreases with increasing ×, which can be attributed to the formation of a stable ion pair (Mn 3+ - Fe 2+ ) due to the doped Mn ions entering the octahedral (B) sites. The real part of complex permeability constant ( μ' ) of ferrites increases with the increase of Mn substitution due to the decreased magneto-crystalline anisotropy. The effective absorption bandwidth (EAB) of ferrites increases from 5.5 GHz to 9.1 GHz with the increase of Mn substitution from x = 0 to 1.6, significantly improving microwave absorption performance. The EAB of Ba 2 Co 2 Mn x Fe 12- x O 22 ferrite at x = 1.2 reaches 8.74 GHz at a thickness of only 1.57 mm, which could be employed as microwave absorbers due to its broad bandwidth, strong absorption, and small thickness. The excellent performance is mainly attributed to the synergy effect of multiple reflections, natural resonance, dipole polarization and good impedance matching.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2021
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IF 5.316
Xin Yu,Siran Xu,Xian Liu,Xiaohong Cheng,Yeshuang Du,Qi Wu
The development of self-supported nanosheet materials with porous multiple active sites has enormous potential for the application of oxygen evolution reaction (OER). Herein, we reported a three-dimensional (3D) porous nanosphere Mn-NiCo 2 S 4 /NF catalyst for OER. As a result, the simple Mn doping strategy results in good electrocatalytic performance and outstanding stability. During the OER, the Mn-NiCo 2 S 4 /NF only needs a small overpotential of 220 mV (40 mV lower than pure NiCo 2 S 4 /NF) to achieve the current density of 10 mA cm −2 , which is mainly due to a large number of exposed active sites and adequate pathways for mass diffusion and oxygen gas release. Moreover, Mn doping optimizes the electronic structure and thus facilitates electron transport , leading to superior electrocatalytic performance. The catalyst exhibits incredible corrosion resistance in 1 M KOH solution for 60 h or more. This work provides a valuable method to synthesize a low cost, high-efficiency, and corrosion resistant transition metal electrocatalyst for oxygen evolution using heteroatom doping strategy.
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Catalysis Science & Technology
·
2021
·Vol. 11
·期 12
·4181-4195
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IF 6.119
Fan Fu,Yufan Zhang,Yan Zhang,Yuyue Chen
In this experiment, Mn@TiO2 nanofibers in the form of membranes were fabricated by ordinary electrospinning and a higher temperature calcination process. Field-emission scanning, X-ray diffraction analysis, X-ray photoelectron spectroscopy, Raman spectra, UV-visible diffuse spectra, UV-visible spectroscopy, and Brunauer–Emmett–Teller (BET) evaluation were used to characterize the resulting samples. The study revealed that, upon the addition of the manganese ion, the continuous and mechanical properties of the nanofibers and nanofilms were substantially enhanced. Notably, after 60 minutes, the Mn@TiO2-0.10 degradation efficiency reached 94.92% under ultraviolet light, which was 5 times greater than that for TiO2 nanofibers. It was due to the controlled mixture phase and palpable raised specific surface area, which ensured a pronounced enhanced photocatalytic activity of the nanofibers. In addition, the application of nanofibers on the capacitor aspect was explored by electrochemical workstations. The highest photoactivity sample performed mass-specific capacity as high as 5.09 F g−1. Such efficient capacity and higher photoactivity of the photocatalyst shed light on the preparation of soft inorganic materials and their application in energy conversion.
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Journal of Energy Chemistry
·
2021
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IF 9.676
Zhiguo Zhang,Hua Huo,Zhenjiang Yu,Lizhi Xiang,Bingxing Xie,Chunyu Du,Jiajun Wang,Geping Yin
Mn doping is deemed as a promising strategy to improve the electrochemical performance of the α-Ni(OH) 2 battery-type supercapacitor electrode. However, the internal structure evolution, the pathways and the dynamics of the proton/intercalated anion migration, as well as the functioning mechanism of Mn dopant to stabilize the layered structure during cycles remain unclear. Here, we unveil that irreversible oxidization of Mn 3+ at the initial CV cycles, which will remain as Mn 4+ in the NiO 2 slabs after the first oxidization to effectively suppress the phase transformation from α-Ni(OH) 2 /γ-NiOOH to β-Ni(OH) 2 /β-NiOOH and further maintain the structural integrity of electrode. With a synergistic combination of theoretical calculations and various structural probes including XRD and 2 H MAS solid state NMR, we decode the structure evolution and dynamics in the initial CV (cyclic voltammetry) cycles, including the absorption/desorption of hydrogen containing species, migration of intercalated anions/water molecules and the change of interlayer space. This present work elucidates a close relationship between doping chemistry and structural reliability, paving a novel way of reengineering supercapacitor electrode materials.
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JOURNAL OF SOLID STATE CHEMISTRY
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2021
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IF 3.498
Zhi Shen,Qiang Zhao,Hai-Quan Xie,Yu-Quan Feng,Shu-Yang Chen,Zhuo Shi
In this study, a multiple binding sites ligand, 5-(4-carboxyphenoxy)nicotinic acid ligand (H 2 cpna), was used to construct metal complexes with Zn 2+ , Cd 2+ , Mn 2+ and Co 2+ by solvothermal reaction, and four new complexes were constructed, namely, [Zn (cpna)•H2O]n (1)，[Cd (cpna) (CH 3 CN)·2H 2 O] n ( 2 ), [Mn (cpna)•2H 2 O] n ( 3 ) and Co(cpna)•2H 2 O] n ( 4 ); All the complexes were characterized by single crystal X-ray diffraction, elemental analysis and infrared analysis in the solid state; Single crystal x-ray diffraction analyses reveal that complexes 1 and 2 have two-dimensional network structures, complexes 3 and 4 have three-dimensional structures. In addition, Luminescence behavior of complex 1 and 2 was investigated and magnetic properties of complex 3 and 4 were studied. The fluorescent test results show that the fluorescence intensity of complex 1 is higher than that of ligand and emission band can be considered as LLCT emission of ligand; The Magnetic results indicate weak ferromagentic interactions in complex 3 and χ m T value rises slowly and then decreases sharply from 300 K to 2 K. However, magnetic results indicate antiferromagentic interactions in complex 4 and χ m T value can be divided into three parts with the change of temperature from 300 K to 2 K.
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JOURNAL OF LUMINESCENCE
·
2021
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IF 3.599
Zhenxing Fang,Kuang Wu,Le Wang,Da Xu,Weiwei Wang,Yuhang Lin,Xiaohui Liu,Chun Sun
Mn doped two-dimensional (2D) layered perovskites , are becoming excellent candidates as red phosphor because of their high quantum yields (QY) and enhanced stability. However, these Mn doped 2D layered perovskites can only be excited by the near UV light , which largely limits the development of perovskites. Herein, blue-excitable Mn-doped PEA 2 (Pb/Mn)(Br/I) 4 PQDs are synthesized from anion exchange surface engineering strategy. After anion exchange, orange Mn 2+ emission from exciton-to-Mn energy transfer is acquired under the excitation of 450 nm. The PEA 2 (Pb/Mn)(Br/I) 4 compounds exhibit strong luminescence with photoluminescence (PL) QY of 52%, which is comparable to most of the reported red emitting phosphors. A prototype white light-emitting diode (WLED) with good optical performance was fabricated using commercial (Sr,Ba) 2 SiO 4 :Eu phosphor and as-prepared PEA 2 (Pb/Mn)(Br/I) 4 as green and orange color converters, showing great potential in the applications of solid state lighting.
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Journal of Physical Chemistry C
·
2020
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IF 4.189
Yubin Zhao,Xiao Zhang,Cong Xie,Wenbin Shi,Ping Yang,San Ping Jiang
Although inorganic cesium halide lead perovskite nanocrystals (NCs) exhibited tunable photoluminescence (PL), it is still a challenge for such NCs with multicolor and white emission for application. In this article, as-synthesized Mn:CsPbCl3 NCs were treated using an oleoamine solution of CdX2 (X = Cl, Br) to get a high PL quantum yield (PLQY) and stability. CdCl2 passivated the surface defects of Mn:CsPbCl3 NCs through anion exchange to get high PL intensity, especially to increase Mn emission. The PLQY of the sample was increased from 15 to 85% after ion exchange. Furthermore, the treatment of CdBr2 resulted in the appearance of a powerful blue emission peak, and the PLQY increased to 95.7%. The PL decay kinetics of samples was studied before and after treatment. Mn2+ emission in Mn:CsPb(Cl/Br)3 NCs was increased because of the reaction of CdBr2 and Mn:CsPbCl3 NCs. Interestingly, the tunable and bright white emission from Mn:CsPb(Cl/Br)3 NCs was obtained by controlling the amount of Br. The controlling of Mn emission plays an important role in changing the Commission Internationale de l’Eclairage color coordinates. Because of bright and tunable PL, the NCs may be used in white-light-emitting diodes.
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Nature Communications
·
2020
·Vol. 11
·期 1
·1-8
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IF 12.121
Feng Jiaqi,Gao Hongshuai,Zheng Lirong,Chen Zhipeng,Zeng Shaojuan,Jiang Chongyang,Dong Haifeng,Liu Licheng,Zhang Suojiang,Zhang Xiangping
Developing effective catalysts based on earth abundant elements is critical for CO 2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO ( j CO ) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N 3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a j CO of 14.0 mA cm −2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher j CO of 29.7 mA cm −2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N 3 site, which facilitates the formation of the key intermediate COOH * through a lowered free energy barrier.
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