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Coupling interface constructions of hollow Co-Mo mixed multiple oxidation states heterostructure for high-performance aprotic Li-O_(2) battery

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Nano Research 2024年第5期17卷 4100-4107页

作者： Xingzi Zheng Mengwei Yuan Jingshen Xu Zihan Li Caiyun Nan genban sun Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China Center for Advanced Materials Research Beijing Normal UniversityZhuhai 519087China

Constructing interfaces in heterostructures is effective for modulating the electronic properties of electrocatalysts.The hollow CoMoO_(4)-Co_(3)O_(4) heterostructure(HCMCH)was prepared as a bifunctional electrocatalyst for Li-O_(2) battery.The different components in CoMoO_(4)-Co_(3)O_(4) heterostructure presented the efficient coupling and enhanced the electrocatalytic activity for aprotic oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),in which it improved the obviously reduced overpotential of 300 mV(compared with the pure Ketjen black(KB)electrode),enhanced reversibility of 80%capacity retention after 6 full cycles and the superior cyclability of more than 200 cycles with an optimized strategy.The battery performance of the HCMCH was not only associated with the unique hollow structure and rich active sites but also with coupling interface constructions synergetic effects attaching to the improving conductivity and optimized the discharge conversion.These results suggested that this HCMCH electrocatalyst was a promising candidate for the Li-O_(2) battery and it gave a novel insight for high performance electrocatalyst designing.

关键词： Li-oxygen battery heterostructure electrocatalyst coupling interface

Rational design of hollow rice-grainedα-Fe_(2)O_(3)/carbon nanofibers with optimized impedance matching for electromagnetic wave absorption enhanced

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Nano Research 2023年第4期16卷 5676-5684页

作者： Jingshen Xu Na Lu Mengwei Yuan genban sun Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China Center for Advanced Materials Research Beijing Normal UniversityZhuhai 519087China

Electromagnetic wave absorption materials are widely used in electronic equipment and military fields.However,high cost and complex preparation processes become a major obstacle in promoting popularization in the civil field.To solve the problems above,researchers have made great efforts to develop Fe-based carbon composites.However,most of the typical composites require a high filling ratio while achieving excellent properties.Therefore,in this study,carbon nanofibers(CNFs)combined with the hollow rice-grainedα-Fe_(2)O_(3)nanoparticles were prepared by the in-situ transformation method.The rational microstructure design provided a solution for reducing the filling ratio,optimizing impedance matching,and improving electromagnetic wave absorption performance.The strong reflection loss value(−38.1 dB)and broad effective absorption bandwidth(4.6 GHz)for Fe_(2)O_(3)/CNFs composites were achieved with a low filling ratio(20 wt.%),and the analysis of electromagnetic parameters validated that the microstructure of Fe_(2)O_(3)/CNFs plays a crucial role in the performance improvement.With the optimized impedance matching and simple preparation method,Fe_(2)O_(3)/CNFs have broad application prospects in electromagnetic wave absorption.

关键词： electromagnetic wave absorption Fe-based carbon nanofibers impedance matching

Recent progress in cathodic reduction-enabled organic electrosynthesis: Trends, challenges, and opportunities

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eScience 2022年第3期2卷 243-277页

作者： Binbin Huang Zemin sun genban sun College of Arts and Sciences Beijing Normal UniversityZhuhai519087China College of Education for the Future Beijing Normal UniversityZhuhai519087China Center for Advanced Materials Research Beijing Normal UniversityZhuhai519087China Beijing Key Laboratory of Energy Conversion and Storage Materials Institution College of ChemistryBeijing Normal UniversityBeijing100875China

Compared with general redox chemistry,electrochemistry using the electron as a potent,controllable,yet traceless alternative to chemical oxidants/reductants usually offers more sustainable options for achieving selective organic synthesis.With its environmentally benign features gradually being uncovered and studied,organic electrosynthesis is currently undergoing a revival and becoming a rapidly growing area within the synthetic community.Among the electrochemical transformations,the anodically enabled ones have been far more extensively exploited than those driven by cathodic reduction,although both approaches are conceptually attractive.To stimulate the development of cathodically enabled organic reactions,this review summarizes the recently developed reductive electrosynthetic protocols,discussing and highlighting reaction features,substrate scopes,applications,and plausible mechanisms to reveal the recent trends in this area.Herein,cathodic reduction-enabled preparative organic transformations are categorized into four types:reduction of(1)unsaturated hydrocarbons,(2)heteroatom-containing carbon-based unsaturated systems,(3)saturated C-hetero or C–C polar/strained bonds,and(4)hetero-hetero linkages.Apart from net electroreductive reactions,a few examples of reductive photo-electrosynthesis as well as paired electrolysis are also introduced,which offer opportunities to overcome certain limitations and improve synthetic versatility.The electrochemically driven,transition metal-catalyzed reductive cross-couplings that have been comprehensively discussed in several other recent reviews are not included here.

关键词： Reductive organic electrosynthesis Cathodic reduction Reductive hydrogenation Reductive functionalization Reductive bond cleavage

Ultrathin hexagonal boron nitride as a van der Waals,force initiator activated graphene for engineering efficient non-metal electrocatalysts of Li-CO_(2) battery

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Nano Research 2022年第2期15卷 1171-1177页

作者： Zemin sun Di Wang Liu Lin Yuhui Liu Mengwei Yuan Caiyun Nan Huifeng Li genban sun Xiaojing Yang Beijing Key Laboratory of Energy Conversion and Storage Materials Institution College of ChemistryBeijing Normal UniversityBeijing 100875China

Reasonably regulating electronic coupling to promote charge transfer and exciton separation has been regarded a promising approach in catalysis.The material engineering of van der Waals heterojunction(vdWsH)based on two-dimensional(2D)materials would be a potential way to optimize the as-prepared extrinsic physicochemical characteristics.However,it was still an almost uncultivated land waiting for exploration in catalysis.Herein,we introduced the inert h-boron nitride(h-BN)in non-metal reduced graphene oxide(GN)catalysts and constructed BN-GN vdWsH.The theoretical calculation demonstrated that the h-BN can effectively modify the electronic properties of graphene.With the introduction of h-BN,the BN-GN vdWsH can obviously enhance the catalytic activity of Li-CO_(2) battery.The existence of BN-GN vdWsH can reduce the overpotential more than 700 mV compared with reduced graphene oxide during the CO_(2) reduction reaction(CO_(2)RR)and CO_(2) evolution reaction(CO_(2)ER),and it extended cyclic stability more than three times,which was one structure design made it work as a high efficient electrocatalyst,catalytic materials.

关键词： van der Waals heterojunction(vdWsH) Li-CO_(2)battery boron nitride-graphene oxide vdWsH non-metal catalysis

Ultralong cycle life enabled by in situ growth of CoMo_(1-x)P/Mo heterostructure for lithium-sulfur batteries

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Journal of Energy Chemistry 2022年第10期31卷 5-12,I0001页

作者： Donghua Guo Mengwei Yuan Xingzi Zheng Miaomiao Li Caiyun Nan genban sun Xianqiang Huang Huifeng Li Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology School of Chemistry&Chemical EngineeringLiaocheng UniversityLiaocheng 252059ShandongChina Department of Physics and Applied Optics Beijing Area Major Laboratory Beijing Normal UniversityBeijing 100875China

Lithium-sulfur batteries(Li-S batteries) are considered as promising new-generation electrochemical energy storage devices due to their extremely high theoretical energy density(2600 Wh kg-1) and theoretical specific capacity(1675 m Ah g^(-1)). However, numerous problems such as poor conductivity and the shuttle effect during discharge-charge process limit the practical application of lithium-sulfur batteries. In this work, porous tubular Co Mo_(1-x)P/Mo constructed by in situ growth of metal Mo was designed as the sulfur host for lithium-sulfur batteries. The introduction of Mo modulated the electronic structure of Co Mo P to improve the conductivity of cathode and facilitate the redox kinetics, as well as the Co Mo_(1-x)P/Mo heterostructure was beneficial to inhibit the shuttle effect through the interaction with lithium polysulfides, which improved cycling stability. As a result, Co Mo_(1-x)P/Mo/S cathode had a low-capacity decay rate of only 0.029% per cycle after 2000 cycles at 0.5 C. This work provided a new perspective for the further design of high-performance lithium-sulfur battery cathode materials.

关键词： Metal phosphide Heterostructure Long cycle Shuttle effect Li-S batteries

Hollow catalysts through different etching treatments to improve active sites and oxygen vacancies for high-performance Li-O_(2)battery

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Nano Research 2023年第5期16卷 6798-6804页

作者： Jiachen Qiu Yuran Lin Shuting Zhang Jie Ma Yu Zhang Mengwei Yuan genban sun Caiyun Nan Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China Center for Advanced Materials Research Beijing Normal UniversityZhuhai 519087China Department of Chemistry Tsinghua UniversityBeijing 100084China

Li-O_(2)batteries are regarded as one of the most promising next-generation battery systems due to their high theoretical energy density,finding effective cathode catalysts with fine-tuned structure is a key way to improve the performance.Herein,based on the structure of cubic zeolitic imidazolate framework-67(ZIF-67),a series of hollow catalysts were synthesized by different chemical etching treatments.Firstly,from the perspective of metal,nickel nitrate is used for etching,hollow Ni ZIF is obtained through Kirkendall effect.Secondly,hollow TA-ZIF is obtained by adding tannic acid to replace the methylimidazole ligand.Hollow structures have larger surface areas,materials can expose more active sites,which can lead to better performance of Li-O_(2)batteries.On this basis,having more oxygen vacancies can also improve the battery performance.At the same time,further loading noble metal ruthenium on the synthesized cobalt-based catalyst can effectively reduce the overpotential of Li-O_(2)battery and improve the battery performance.For TA-ZIF with more stable hollow structure and more oxygen vacancies,the cycle performance reaches 330 cycles after loading Ru.Compared with the 64 cycles of solid Co_(3)O_(4),it has a great improvement.

关键词： hollow structure active sites oxygen vacancies noble metal cathode catalyst Li-O_(2)battery

In situ decoration of nanosized metal oxide on highly conductive MXene nanosheets as efficient catalyst for Li-O2 battery

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Journal of Energy Chemistry 2020年第8期29卷 272-280,I0010页

作者： Xingyu Li Caiying Wen Huifeng Li genban sun Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China

Combining nanomaterials with complementary properties in a well-designed structure is an effective tactic to exploit multifunctional, high-performance materials for the energy conversion and storage. Nonprecious metal catalysts, such as cobalt oxide, with superior activity and excellent stability to other catalysts are widely desired. Nevertheless, the performance of CoO nanoparticles as an electrode material were significantly limit for its inferior conductivity, dissolution, and high cohesion. Herein, we grow ultrafine cobalt monoxide to decorate the interlayer and surface of the Ti3C2 Txnanosheets via a hydrothermal method companied by calcination. The layered MXenes act as the underlying conductive substrate,which not only increase the electron transfer rate at the interface but also greatly improve the electrochemical properties of the nanosized Co O particles by restricting the aggregation of CoO. The resulting CoO/Ti3C2 Txnanomaterial is applied as oxygen electrode for lithium-oxygen battery and achieves more than 160 cycles and first cycle capacity of 16,220 mAh g-1 at 100 mA g-1. This work paves a promising avenue for constructing a bi-functional catalyst by coupling the active component of a transition metal oxide(TMO) with the MXene materials in lithium-oxygen battery.

关键词： MXene Nanosized CoO Li-O2 batteries Cathode catalyst

Enhanced microwave absorption performance of highly dispersed CoNi nanostructures arrayed on graphene

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Nano Research 2018年第5期11卷 2689-2704页

作者： genban sun Hong Wu Qingliang Liao Yue Zhang State Key Laboratory for Advanced Metals and Materials School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry Beijing Normal University Beijing 100875 China

Magnetic metals （Fe, Co, Ni） and alloys thereof are easily synthesized as nanoparticles, but obtaining highly dispersed graphene-based magnetic nanomaterials remains challenging. Here, three CoNi/graphene nanocomposites （CoNi/GN） are successfully assembled for the first time via a one-pot strategy without templating by manipulating the reaction time and solvents used for the same precursors. Moreover, the reduction of graphene oxide utilizing this method is more effective than that by conventional methods and the alloy particles are firmly embedded on the GN substrate. Compared to n- and p-CoNi/GN nanocomposites, o-CoNi/GN nanocomposites show the best electromagnetic wave absorption properties with the maximum reflection loss of -31.0 dB at 4.9 GHz for a thickness of 4 mm; the effective absorption bandwidth （〈 10.0 dB） is 7.3 GHz （9.5-16.8 GHz） for a thickness of 2 mm. The structures and electromagnetic wave absorption mechanisms of the three composites were also investigated. This research provides a new platform for the development of magnetic alloy nanoparticles in the field of microwave-absorbing devices.

关键词： CoNi/graphene nanocomposites,nanoclusters,alloy,microwave absorption,electromagnetism

In situ decoration of CoP/Ti_(3)C_(2)Tx composite as efficient electrocatalyst for Li-oxygen battery

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Chinese Chemical Letters 2023年第1期34卷 164-168页

作者： Xingzi Zheng Mengwei Yuan Xianqiang Huang Huifeng Li genban sun Beijing Key Laboratory of Energy Conversion and Storage Materials College of ChemistryBeijing Normal UniversityBeijing 100875China Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology School of Chemistry&Chemical EngineeringLiaocheng UniversityLiaocheng 252059China Department of Physics and Applied Optics Beijing Area Major Laboratory Beijing Normal UniversityBeijing 100875China

Application of Li-oxygen(Li-O_(2)) battery is in urgent need of bifunctional ORR/OER electrocatalyst. A surface-functionalization CoP/Ti_(3)C_(2)Txcomposite was fabricated theoretically, with the optimized electronic structure and more active electron, which is beneficial to the electrochemical reaction. The accordion shaped Ti_(3)C_(2)Txis featured with large specific surface area and outstanding electronic conductivity, which is beneficial for the adequate exposure of active sites and the deposition of Li2O2. Transition metal phosphides provide more electrocatalytic active sites and present good electrocatalytic effect. The CoP/Ti_(3)C_(2)Txcomposite served as the electrocatalyst of Li-O_(2)battery reaches a high specific discharge capacity of 17,413 m Ah/g at 100 m A/g and the lower overpotential of 1.25 V, superior to those of the CoP and Ti_(3)C_(2)Txindividually. The composite of transition metal phosphides and MXene are applied in Li-O_(2)battery, not only demonstrating higher cycling stability of the prepared CoP/Ti_(3)C_(2)Txcomposite, but pointing out the direction for their electrochemical performance improvement.

关键词： MXene Transition metal phosphide Oxygen adsorption ability Li-oxygen battery Electrocatalyst