Publications by authors named "Fangyi Cheng"

87 Publications

Electrodeposition of Pt-Decorated Ni(OH)/CeO Hybrid as Superior Bifunctional Electrocatalyst for Water Splitting.

Research (Wash D C) 2020 15;2020:9068270. Epub 2020 Dec 15.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center, College of Chemistry, Nankai University, Tianjin 300071, China.

The facile synthesis of highly active and stable bifunctional electrocatalysts to catalyze water splitting is attractive but challenging. Herein, we report the electrodeposition of Pt-decorated Ni(OH)/CeO (PNC) hybrid as an efficient and robust bifunctional electrocatalyst. The graphite-supported PNC catalyst delivers superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities over the benchmark Pt/C and RuO, respectively. For overall water electrolysis, the PNC hybrid only requires a cell voltage of 1.45 V at 10 mA cm and sustains over 85 h at 1000 mA cm. The remarkable HER/OER performances are attributed to the superhydrophilicity and multiple effects of PNC, in which Ni(OH) and CeO accelerate HER on Pt due to promoted water dissociation and strong electronic interaction, while the electron-pulling Ce cations facilitate the generation of high-valence Ni OER-active species. These results suggest the promising application of PNC for H production from water electrolysis.
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http://dx.doi.org/10.34133/2020/9068270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7877398PMC
December 2020

Electroless Formation of a Fluorinated Li/Na Hybrid Interphase for Robust Lithium Anodes.

J Am Chem Soc 2021 Feb 15;143(7):2829-2837. Epub 2021 Feb 15.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Research Center of High-Efficiency Energy Storage (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, P. R. China.

Engineering a stable solid electrolyte interphase (SEI) is one of the critical maneuvers in improving the performance of a lithium anode for high-energy-density rechargeable lithium batteries. Herein, we build a fluorinated lithium/sodium hybrid interphase via a facile electroless electrolyte-soaking approach to stabilize the repeated plating/stripping of lithium metal. Jointed experimental and computational characterizations reveal that the fluorinated hybrid SEI mainly consisting of NaF, LiF, LiPOF, and organic components features a mosaic polycrystalline structure with enriched grain boundaries and superior interfacial properties toward Li. This LiF/NaF hybrid SEI exhibits improved ionic conductivity and mechanical strength in comparison to the SEI without NaF. Remarkably, the fluorinated hybrid SEI enables an extended dendrite-free cycling of metallic Li over 1300 h at a high areal capacity of 10 mAh cm in symmetrical cells. Furthermore, full cells based on the LiFePO cathode and hybrid SEI-protected Li anode sustain long-term stability and good capacity retention (96.70% after 200 cycles) at 0.5 C. This work could provide a new avenue for designing robust multifunctional SEI to upgrade the metallic lithium anode.
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http://dx.doi.org/10.1021/jacs.0c12051DOI Listing
February 2021

Growing Nanostructured CuO on Copper Foil via Chemical Etching to Upgrade Metallic Lithium Anode.

ACS Appl Mater Interfaces 2021 Feb 26;13(5):6367-6374. Epub 2021 Jan 26.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Engineering Research Center of High-efficiency Energy Storage (Ministry of Education), Renewable Energy Conversion and Storage Center, College of Chemistry, Nankai University, Tianjin 300071, China.

Metallic lithium is one of the most promising anode materials to build next generation electrochemical power sources such as Li-air, Li-sulfur, and solid-state lithium batteries. The implementation of rechargeable Li-based batteries is plagued by issues including dendrites, pulverization, and an unstable solid electrolyte interface (SEI). Herein, we report the use of nanostructured CuO grown on commercial copper foil (CuO@Cu) via chemical etching as a Li-reservoir substrate to stabilize SEI formation and Li stripping/plating. The lithiophilic interconnected CuO layer enhances electrolyte wettability. Besides, a mechanically stable LiO- and LiF-rich SEI is generated on CuO@Cu during initial discharge, which permits dense and uniform lithium deposition upon subsequent cycling. Compared with bare Cu, the CuO@Cu electrode exhibits superior performance in terms of Coulombic efficiency, discharge/charge overpotentials, and cyclability. By pairing with the Li-CuO@Cu anodes, full cells with LiFePO and LiNiMnCoO cathodes sustain 300 cycles with 98.8% capacity retention at 1 C and deliver a specific capacity of 80 mAh g at 10 C, respectively. This work would shed light on the design of advanced current collectors with SEI modulation to upgrade lithium anodes.
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http://dx.doi.org/10.1021/acsami.0c22046DOI Listing
February 2021

Isolated diatomic Zn-Fe in N-doped carbon for electrocatalytic nitrogen reduction to ammonia.

Chem Commun (Camb) 2020 Oct 7;56(80):11957-11960. Epub 2020 Sep 7.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin 300071, China.

Isolated diatomic Zn-Fe anchored on nitrogen-doped carbon is explored as an efficient and robust electrocatalyst for N reduction in a neutral aqueous electrolyte, delivering a high NH yield rate (30.5 μg h mg) and considerable faradaic efficiency (26.5%) at a low overpotential of -300 mV. Density functional theory calculations reveal that the Zn-Fe atomic pairs synergistically favor N activation and reduce the reaction barrier for the rate-limiting step of intermediate *NNH formation.
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http://dx.doi.org/10.1039/d0cc04843gDOI Listing
October 2020

Materials chemistry for rechargeable zinc-ion batteries.

Chem Soc Rev 2020 Jul;49(13):4203-4219

Renewable Energy Conversion and Storage Center, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, China.

Rechargeable zinc-ion batteries (ZIBs) are promising for large scale energy storage and portable electronic applications due to their low cost, material abundance, high safety, acceptable energy density and environmental friendliness. This tutorial review presents an introduction to the fundamentals, challenges, recent advances and prospects related to ZIBs. Firstly, the intrinsic chemical properties, challenges and strategies of metallic zinc anodes are underscored. Then, the multiple types of cathode materials are classified and comparatively discussed in terms of their structural and electrochemical properties, issues and remedies. Specific attention is paid to the mechanistic understanding and structural transformation of cathode materials based on Zn ion-(de)intercalation chemistry. After that, the widely investigated electrolytes are elaborated by discussing their effect on Zn plating/stripping behaviours, reaction kinetics, electrode/electrolyte interface chemistries, and cell performances. Finally, the remaining challenges and future perspectives are outlined for the development of ZIBs.
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http://dx.doi.org/10.1039/c9cs00349eDOI Listing
July 2020

Plasmon-promoted electrocatalytic water splitting on metal-semiconductor nanocomposites: the interfacial charge transfer and the real catalytic sites.

Chem Sci 2019 Nov 29;10(41):9605-9612. Epub 2019 Aug 29.

Key Lab of Advanced Energy Materials Chemistry (Ministry of Education) , Renewable Energy Conversion and Storage Center , College of Chemistry , Nankai University , Weijin Rd. 94 , Tianjin 300071 , China . Email:

Plasmonic metal nanoparticles (NPs) have emerged as promising visible light harvesters to facilitate solar-to-chemical energy conversion the generation of hot electrons by non-radiative decay of plasmons. As one of the most promising renewable energy production methods for the future, electrocatalytic water splitting is an ideal chemical reaction in which plasmonic NPs can be utilized for direct solar-to-fuel conversion. Due to the rapid carrier recombination on plasmonic NPs, hybrid photocatalysts integrating metals and semiconductors are usually employed to separate the hot electrons and holes. However, an understanding of the catalytic mechanism, which is critical for rational design of plasmonic electrocatalysts, including the interfacial charge transfer pathway and real reactive sites, has been lacking. Herein, we report on the combination of plasmonic Au NPs and semiconductors (Ni and/or Co hydroxides) for plasmon-promoted electrocatalytic water splitting. By using surface-enhanced Raman spectroscopy (SERS), we find a strong spontaneous interfacial charge transfer between Au and NiCo layered double hydroxide (LDH), which facilitates both the oxygen and hydrogen evolution reactions. The real catalytic sites on the hybrid material are confirmed by selective blocking of the metal surface with a thiol molecular monolayer. It is found that the plasmon-promoted oxygen evolution occurs on the LDH semiconductor but surprisingly, the hydrogen evolution sites are mainly located on the Au NP surface. This work demonstrates the critical role of interfacial charge transfer in hot electron-driven water splitting and paves the way for rational design of high-performance plasmonic electrocatalysts.
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http://dx.doi.org/10.1039/c9sc03360bDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993609PMC
November 2019

Facile synthesis of amorphous MoS-Fe anchored on Zr-MOFs towards efficient and stable electrocatalytic hydrogen evolution.

Chem Commun (Camb) 2020 Mar 5;56(18):2763-2766. Epub 2020 Feb 5.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center, College of Chemistry, Nankai University, Tianjin 300071, China.

A litchi-like MoS-Fe@UiO-66-(OH) nanocomposite with amorphous MoS-Fe nanoparticles uniformly anchored on the surface of UiO-66-(OH) is synthesized through sequential room-temperature redox and coordination reaction. The composite exhibits high catalytic activity and durability for hydrogen evolution in an acidic electrolyte, delivering 1000 mA cm at -297 mV and outperforming Pt/C under high current densities.
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http://dx.doi.org/10.1039/c9cc08771kDOI Listing
March 2020

Materials Science at Nankai: A Special Issue Dedicated to the 100th Anniversary of Nankai University.

Adv Mater 2020 01;32(3):e1907314

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Renewable Energy Conversion and Storage Center, Nankai University, Weijin Road 94, Tianjin, 300071, P. R. China.

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http://dx.doi.org/10.1002/adma.201907314DOI Listing
January 2020

Nanoporous Palladium Hydride for Electrocatalytic N Reduction under Ambient Conditions.

Angew Chem Int Ed Engl 2020 Feb 24;59(9):3511-3516. Epub 2020 Jan 24.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Engineering Research Center of High-efficiency Energy Storage (Ministry of Education), Renewable Energy Conversion and Storage Center, College of Chemistry, Nankai University, Tianjin, 300071, China.

The electrocatalytic nitrogen reduction reaction (NRR) is an alternative eco-friendly strategy for sustainable N fixation with renewable energy. However, NRR suffers from sluggish kinetics owing to difficult N adsorption and N≡N cleavage. Now, nanoporous palladium hydride is reported as electrocatalyst for electrochemical N reduction under ambient conditions, achieving a high ammonia yield rate of 20.4 μg h  mg with a Faradaic efficiency of 43.6 % at low overpotential of 150 mV. Isotopic hydrogen labeling studies suggest the involvement of lattice hydrogen atoms in the hydride as active hydrogen source. In situ Raman analysis and density functional theory (DFT) calculations further reveal the reduction of energy barrier for the rate-limiting *N H formation step. The unique protonation mode of palladium hydride would provide a new insight on designing efficient and robust electrocatalysts for nitrogen fixation.
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http://dx.doi.org/10.1002/anie.201914335DOI Listing
February 2020

Microsized Antimony as a Stable Anode in Fluoroethylene Carbonate Containing Electrolytes for Rechargeable Lithium-/Sodium-Ion Batteries.

ACS Appl Mater Interfaces 2020 Jan 10;12(3):3554-3562. Epub 2020 Jan 10.

College of Chemistry & Environmental Science, Key Laboratory of Analytical Science and Technology of Hebei Province , Hebei University , Baoding 071002 , China.

Metallic antimony (Sb) is an attractive anode material for lithium-/sodium-ion batteries (LIBs/SIBs) because of its high theoretical capacity (660 mA h g), but it suffers from poor cycling performance caused by the huge volume expansion and the unstable solid electrolyte interphase (SEI). Here, we report a high-performing microsized Sb anode for both LIBs and SIBs by coupling it with fluoroethylene carbonate (FEC) containing electrolytes. The optimum amount of FEC (10 vol %) renders a stable LiF/NaF-rich SEI on Sb electrodes that can suppress the continuous electrolyte decomposition and accommodate the volume variation. The microsized Sb electrode gradually evolves into a porous integrity assembled by nanoparticles in FEC-containing electrolytes during cycling, which is totally different from that in the FEC-free counterpart. As a result, the microsized Sb electrodes exhibit a reversible capacity of 540 mA h g with 85.3% capacity retention after 150 cycles at 1000 mA g for LIBs and 605 mA h g with 95.4% capacity retention after 150 cycles at 200 mA g for SIBs. More impressively, the prototype full Li-based (i.e., Sb/LiNiCoMnO cell) and Na-based (i.e., Sb/NaV(PO)OF cell) batteries also achieve good cycling durability. This facile strategy of electrolyte formulation to boost the cycling performance of microsized Sb anodes will provide a new avenue for developing stable alloying-type materials for both LIBs and SIBs.
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http://dx.doi.org/10.1021/acsami.9b18006DOI Listing
January 2020

Tuning Oxygen Redox Chemistry in Li-Rich Mn-Based Layered Oxide Cathodes by Modulating Cation Arrangement.

Adv Mater 2019 Oct 2;31(42):e1901808. Epub 2019 Sep 2.

Key Laboratory of Advanced Energy Materials Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China.

Li-rich Mn-based oxides (LRMO) are promising cathode materials to build next-generation lithium-ion batteries with high energy density exceeding 400 W h kg . However, due to a lack of in-depth understanding of oxygen redox chemistry in LRMO, voltage decay is not resolved thoroughly. Here, it is demonstrated that the oxygen redox chemistry could be tuned by modulating cation arrangement. It declares that the materials with Li/Ni disorder and Li vacancies can inhibit the formation of OO dimers. Because of the high chemical activity, OO dimers could accelerate lattice oxygen release and NiO/spinel formation. The samples without forming OO dimers show improved performance in suppressing oxygen overoxidation and mitigating cation dissolution. As a result, the optimized cathode exhibits a high capacity over 280 mA h g at 0.1 C and a high plateau voltage of 3.58 V with a very low voltage decay of 1.6% after 150 cycles at 1 C. This study opens an attractive path in designing Li-rich electrodes with stabilized redox chemistry.
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http://dx.doi.org/10.1002/adma.201901808DOI Listing
October 2019

Ultrafast Rechargeable Zinc Battery Based on High-Voltage Graphite Cathode and Stable Nonaqueous Electrolyte.

ACS Appl Mater Interfaces 2019 Sep 28;11(36):32978-32986. Epub 2019 Aug 28.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry , Nankai University , Tianjin 300071 , China.

Zinc-based battery chemistries have lately drawn great attention for grid-scale energy storage due to their material abundance and high safety. However, the low Coulombic efficiency (CE) and dendrite growth of zinc (Zn) anodes and the limited working voltage of current oxide cathodes are the major barriers hindering the development of rechargeable Zn-based batteries (RZBs). Here, we report an ultrafast and high-voltage Zn battery in a new cell configuration employing a graphite cathode, a Zn anode, and nonaqueous 1 M zinc bis(trifluoromethylsulfonyl)imide (Zn(TFSI)) in acetonitrile (AN) electrolyte. This RZB operates through the (de)intercalation of TFSI anions into the graphite and the electrochemical Zn plating/stripping at the anode. The optimized Zn(TFSI)/AN electrolyte features high reductive/oxidative stability, good ionic conductivity (∼28 mS cm), and low viscosity (∼0.4 mPa·s), enabling the unprecedented cycling stability (over 1000 h) of the Zn anode with a dendrite-free morphology, the ultrafast Zn plating/stripping with a high CE (>99%), and the good compatibility with the graphite cathode. Consequently, this RZB exhibits a high average output voltage (2.2 V), a high energy/power density (86.5 Wh kg at 4400 W kg), and a long cycle life (97.3% capacity retention after 1000 cycles). The present work offers new insights and opportunities to the Zn-based electrochemistry.
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http://dx.doi.org/10.1021/acsami.9b10399DOI Listing
September 2019

Synthesis of Ni/NiO@MIL-101(Cr) Composite as Novel Anode for Lithium-Ion Battery Application.

J Nanosci Nanotechnol 2019 Dec;19(12):8063-8070

Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan, 430062, China.

The poor conductivity is one of the prime reasons restricted MOFs to be applied in the lithium-ion battery system. For the sake of ameliorate this issue, the Ni/NiO was well loaded on the surface of Cr-based metal organic frameworks (MIL-101) by solution impregnation and reduction method to form Ni/NiO@MIL-101(Cr) composites. The as-synthesized Ni/NiO@MIL-101(Cr) was characterized by X-ray powder diffractions, X-ray photoelectron spectroscopy, field emission scanning electron microscope and transmission electron microscope techniques. When used as anode for LIBs, the Ni/NiO@MIL-101(Cr) composite exhibited high reversible capacity (891 mAh g after 100 cycles at a current density of 200 mA g) and stable cycle performance, the coulombic efficiency can maintain in the whole cycle above 95.0%. The reasons for that Ni/NiO@MIL-101(Cr) behaved outstanding electrochemical properties were discussed also. The Ni/NiO@MIL-101(Cr) can be used as promising material for lithium-ion battery application.
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http://dx.doi.org/10.1166/jnn.2019.16763DOI Listing
December 2019

Direct Spectroscopy for Probing the Critical Role of Partial Covalency in Oxygen Reduction Reaction for Cobalt-Manganese Spinel Oxides.

Nanomaterials (Basel) 2019 Apr 9;9(4). Epub 2019 Apr 9.

State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.

Nanocrystalline multivalent metal spinels are considered as attractive non-precious oxygen electrocatalysts. Identifying their active sites and understanding their reaction mechanisms are essential to explore novel transition metal (TM) oxides catalysts and further promote their catalytic efficiency. Here we report a systematic investigation, by means of soft X-ray absorption spectroscopy (sXAS), on cubic and tetragonal CoMnO₄ (x = 1, 1.5, 2) spinel oxides as a family of highly active catalysts for the oxygen reduction reaction (ORR). We demonstrate that the ORR activity for oxide catalysts primarily correlates to the partial covalency of between O 2p orbital with Mn 3d t-down/e-up, Mn 3d e-up and Co 3d e-up orbitals in octahedron, which is directly revealed by the O K-edge sXAS. Our findings propose the critical influences of the partial covalency between oxygen 2p band and specific metal 3d band on the competition between intermediates displacement of the ORR, and thus highlight the importance of electronic structure in controlling oxide catalytic activity.
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http://dx.doi.org/10.3390/nano9040577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523907PMC
April 2019

Self-Supported Transition-Metal-Based Electrocatalysts for Hydrogen and Oxygen Evolution.

Adv Mater 2020 Jan 1;32(3):e1806326. Epub 2019 Apr 1.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Renewable Energy Conversion and Storage Center, Nankai University, Tianjin, 300071, China.

Electrochemical water splitting is a promising technology for sustainable conversion, storage, and transport of hydrogen energy. Searching for earth-abundant hydrogen/oxygen evolution reaction (HER/OER) electrocatalysts with high activity and durability to replace noble-metal-based catalysts plays paramount importance in the scalable application of water electrolysis. A freestanding electrode architecture is highly attractive as compared to the conventional coated powdery form because of enhanced kinetics and stability. Herein, recent progress in developing transition-metal-based HER/OER electrocatalytic materials is reviewed with selected examples of chalcogenides, phosphides, carbides, nitrides, alloys, phosphates, oxides, hydroxides, and oxyhydroxides. Focusing on self-supported electrodes, the latest advances in their structural design, controllable synthesis, mechanistic understanding, and strategies for performance enhancement are presented. Remaining challenges and future perspectives for the further development of self-supported electrocatalysts are also discussed.
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http://dx.doi.org/10.1002/adma.201806326DOI Listing
January 2020

Stabilizing nickel-rich layered oxide cathodes by magnesium doping for rechargeable lithium-ion batteries.

Chem Sci 2019 Feb 12;10(5):1374-1379. Epub 2018 Nov 12.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) , College of Chemistry , Nankai University , Tianjin 300071 , China . Email:

Nickel-rich layered transition metal oxides are attractive cathode materials for rechargeable lithium-ion batteries but suffer from inherent structural and thermal instabilities that limit the deliverable capacity and cycling performance on charging to a cutoff voltage above 4.3 V. Here we report LiNiCoMgO as a stable cathode material. The obtained LiNiCoMgO microspheres exhibit high capacity (228.3 mA h g at 0.1C) and remarkable cyclability (84.3% capacity retention after 300 cycles). Combined X-ray diffraction and Cs-corrected microscopy reveal that Mg doping stabilizes the layered structure by suppressing Li/Ni cation mixing and Ni migration to interlayer Li slabs. Because of the pillar effect of Mg in Li sites, LiNiCoMgO shows decent thermal stability and small lattice variation until it is charged to 4.7 V, undergoing a H1-H2 phase transition without discernible formation of an unstable H3 phase. The results indicate that moderate Mg doping is a facile yet effective strategy to develop high-performance Ni-rich cathode materials.
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http://dx.doi.org/10.1039/c8sc03385dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6354825PMC
February 2019

Activation of defective nickel molybdate nanowires for enhanced alkaline electrochemical hydrogen evolution.

Nanoscale 2018 Sep;10(35):16539-16546

State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.

Designing highly-efficient and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) in an alkaline solution is more complex and sluggish than for an acidic one. Herein, we report a controllable N-doping strategy to synthesize a series of N-doped porous metallic NiMoO4 nanowires with concomitant oxygen vacancy defects (N-Vo-NiMoO4 NWs) for promoting the alkaline HER ability and durability. Both experimental and theoretical results demonstrate that the doped-N at NiO6 octahedral sites and the abundant oxygen vacancy defects confined in N-Vo-NiMoO4 NWs with modified electronic arrangement could enhance the metallic conductivity, affect the surface areas, and lower the adsorption energy of hydrogen, resulting in an increased HER property. However, the excess doped-N leads to an opposite effect due to the reduced valence state of Ni centres. Therefore, alkaline HER ability of N-Vo-NiMoO4 NWs exhibits a volcano-like trend vs. the nitrogen content, with N3-Vo-NiMoO4 NWs being the best one. As a result, the N3-Vo-NiMoO4 NWs show nearly zero onset overpotential, an overpotential of 55 mV at 10 mA cm-2, and a Tafel slope of only 38 mV dec-1 in 1.0 M KOH, which are superior to those of state-of-the-art platinum-free electrocatalysts.
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http://dx.doi.org/10.1039/c8nr05723kDOI Listing
September 2018

Enhancing the Lithium Storage Capacities of Coordination Compounds for Advanced Lithium-Ion Battery Anodes via a Coordination Chemistry Approach.

Inorg Chem 2018 Sep 20;57(17):10640-10648. Epub 2018 Aug 20.

Department of Chemistry, College of Chemistry , Nankai University , Tianjin 300071 , China.

The influence of the water molecule on both the structural dimensionality and the lithium storage capacities of four coordination compounds was studied. Increasing the reaction temperature to remove the terminal water ligand of discrete coordination compounds [M(HNA)(HO)] (HNA = 5-hydroxynicotinic acid, M = Co for 1 and Ni for 2) led to forming three-dimensional (3D) coordination polymers [M(NA)] (M = Co for 3 and Ni for 4). When 1-4 were investigated as active anode materials for lithium storage at 100 mA g, the relatively low capacities of 455 and 411 mA h g were obtained after 60 cycles with discrete 1 and 2, while that of 3 and 4 showed high capacities of 618 and 610 mA h g after 100 cycles. Detailed mechanism studies by powder X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy showed that the structural dimensionality change induced by water molecules can greatly contribute the cyclability and rate performance for coordination compounds as anode material for lithium storage.
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http://dx.doi.org/10.1021/acs.inorgchem.8b01295DOI Listing
September 2018

Enlarged CoO Covalency in Octahedral Sites Leading to Highly Efficient Spinel Oxides for Oxygen Evolution Reaction.

Adv Mater 2018 Aug 25;30(32):e1802912. Epub 2018 Jun 25.

School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.

Cobalt-containing spinel oxides are promising electrocatalysts for the oxygen evolution reaction (OER) owing to their remarkable activity and durability. However, the activity still needs further improvement and related fundamentals remain untouched. The fact that spinel oxides tend to form cation deficiencies can differentiate their electrocatalysis from other oxide materials, for example, the most studied oxygen-deficient perovskites. Here, a systematic study of spinel ZnFe Co O oxides (x = 0-2.0) toward the OER is presented and a highly active catalyst superior to benchmark IrO is developed. The distinctive OER activity is found to be dominated by the metal-oxygen covalency and an enlarged CoO covalency by 10-30 at% Fe substitution is responsible for the activity enhancement. While the pH-dependent OER activity of ZnFe Co O (the optimal one) indicates decoupled proton-electron transfers during the OER, the involvement of lattice oxygen is not considered as a favorable route because of the downshifted O p-band center relative to Fermi level governed by the spinel's cation deficient nature.
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http://dx.doi.org/10.1002/adma.201802912DOI Listing
August 2018

Anion insertion enhanced electrodeposition of robust metal hydroxide/oxide electrodes for oxygen evolution.

Nat Commun 2018 06 18;9(1):2373. Epub 2018 Jun 18.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin, 300071, China.

Electrochemical deposition is a facile strategy to prepare functional materials but suffers from limitation in thin films and uncontrollable interface engineering. Here we report a universal electrosynthesis of metal hydroxides/oxides on varied substrates via reduction of oxyacid anions. On graphitic substrates, we find that the insertion of nitrate ion in graphene layers significantly enhances the electrodeposit-support interface, resulting in high mass loading and super hydrophilic/aerophobic properties. For the electrocatalytic oxygen evolution reaction, the nanocrystalline cerium dioxide and amorphous nickel hydroxide co-electrodeposited on graphite exhibits low overpotential (177 mV@10 mA cm) and sustains long-term durability (over 300 h) at a large current density of 1000 mA cm. In situ Raman and operando X-ray diffraction unravel that the integration of cerium promotes the formation of electrocatalytically active gamma-phase nickel oxyhydroxide with exposed (003) facets. Therefore, combining anion intercalation with cathodic electrodeposition allows building robust electrodes with high electrochemical performance.
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http://dx.doi.org/10.1038/s41467-018-04788-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6006371PMC
June 2018

FeS /CoS Interface Nanosheets as Efficient Bifunctional Electrocatalyst for Overall Water Splitting.

Small 2018 Jun 28;14(26):e1801070. Epub 2018 May 28.

State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.

Electrochemical water splitting to produce hydrogen and oxygen, as an important reaction for renewable energy storage, needs highly efficient and stable catalysts. Herein, FeS /CoS interface nanosheets (NSs) as efficient bifunctional electrocatalysts for overall water splitting are reported. The thickness and interface disordered structure with rich defects of FeS /CoS NSs are confirmed by atomic force microscopy and high-resolution transmission electron microscopy. Furthermore, extended X-ray absorption fine structure spectroscopy clarifies that FeS /CoS NSs with sulfur vacancies, which can further increase electrocatalytic performance. Benefiting from the interface nanosheets' structure with abundant defects, the FeS /CoS NSs show remarkable hydrogen evolution reaction (HER) performance with a low overpotential of 78.2 mV at 10 mA cm and a superior stability for 80 h in 1.0 m KOH, and an overpotential of 302 mV at 100 mA cm for the oxygen evolution reaction (OER). More importantly, the FeS /CoS NSs display excellent performance for overall water splitting with a voltage of 1.47 V to achieve current density of 10 mA cm and maintain the activity for at least 21 h. The present work highlights the importance of engineering interface nanosheets with rich defects based on transition metal dichalcogenides for boosting the HER and OER performance.
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http://dx.doi.org/10.1002/smll.201801070DOI Listing
June 2018

Rechargeable aqueous zinc-iodine batteries: pore confining mechanism and flexible device application.

Chem Commun (Camb) 2018 Jun;54(50):6792-6795

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, China.

Here we report a flexible and rechargeable aqueous Zn-iodine battery with an iodine/carbon cloth cathode. Combined experimental and computational studies suggest that the battery undergoes a reversible reaction of Zn + I2 ↔ ZnI2 with suppressed I3- formation by confining iodine species in porous carbon.
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http://dx.doi.org/10.1039/c8cc02616eDOI Listing
June 2018

The structure-electrochemical property relationship of quinone electrodes for lithium-ion batteries.

Phys Chem Chem Phys 2018 May;20(19):13478-13484

State key Laboratory of Elemento-Organic Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Collaborative Innovation Center of Chemical Science and Engineering, College of Chemistry, Nankai University, Tianjin 300071, China.

Quinones are promising electrode materials for lithium-ion batteries (LIBs), but their structure-electrochemical property relationship remains unclear. The aim of this study is to unravel the structural influence on the electrochemical properties of different quinones in LIBs. Through density functional theory calculations, redox potentials of 20 parent quinone isomers were examined, which revealed an increasing order of redox potentials as para-quinones < discrete-quinones < ortho-quinones. Two new methods were introduced to calculate and design organic electrode materials rationally. One is the vertical electron affinity in consideration of solvation effect, which was used to estimate the number of electron accommodation for quinones during lithiation. The other is a new index denoted as ΔA2Li used in para- and ortho-quinones, which was introduced to reveal the relationship between aromaticity and redox potential, establishing the theoretical basis for the design of analogous high-voltage organic electrode materials of LIBs.
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http://dx.doi.org/10.1039/c8cp00597dDOI Listing
May 2018

Metallic CuCoS nanosheets of atomic thickness as efficient bifunctional electrocatalysts for portable, flexible Zn-air batteries.

Nanoscale 2018 Apr;10(14):6581-6588

State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.

Optimized catalysts show great potential for renewable energy storage and conversion. Herein, we report metallic CuCo2S4 nanosheets (NSs) of atomic thickness as efficient bifunctional electrocatalysts for use in portable, flexible Zn-air batteries. The metallic CuCo2S4 NSs of atomic thickness with 4-atom-thick to 6-atom-thick layers are confirmed by temperature-dependent electrical resistance measurements and atomic force microscopy. Furthermore, extended X-ray absorption fine structure spectroscopy confirms that CuCo2S4 NSs with sulfur vacancies can further increase the OER activity. Due to high electrical conductivity and ultrathin nanosheet structure with abundant defects, CuCo2S4 NSs exhibit excellent reversible oxygen catalytic performance with an overpotential of 287 mV (at j = 10 mA cm-2) for the oxygen evolution reaction (OER) and an onset potential of 0.90 V for the oxygen reduction reaction (ORR). Additionally, the portable, flexible Zn-air battery using CuCo2S4 NSs as the air-cathode displays a high open circuit voltage and strong rechargeable capacity for 18 h. The present study highlights the importance of designing metallic catalysts having atomic thickness with surface defects for highly efficient and stable renewable energy storage and conversion.
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http://dx.doi.org/10.1039/c8nr01381kDOI Listing
April 2018

Uniform MnCoO Porous Dumbbells for Lithium-Ion Batteries and Oxygen Evolution Reactions.

ACS Appl Mater Interfaces 2018 Mar 5;10(10):8730-8738. Epub 2018 Mar 5.

School of Materials Science & Engineering , Central South University , Changsha , Hunan 410083 , China.

Three-dimensional (3D) binary oxides with hierarchical porous nanostructures are attracting increasing attentions as electrode materials in energy storage and conversion systems because of their structural superiority which not only create desired electronic and ion transport channels but also possess better structural mechanical stability. Herein, unusual 3D hierarchical MnCoO porous dumbbells have been synthesized by a facile solvothermal method combined with a following heat treatment in air. The as-obtained MnCoO dumbbells are composed of tightly stacked nanorods and show a large specific surface area of 41.30 m g with a pore size distribution of 2-10 nm. As an anode material for lithium-ion batteries (LIBs), the MnCoO dumbbell electrode exhibits high reversible capacity and good rate capability, where a stable reversible capacity of 955 mA h g can be maintained after 180 cycles at 200 mA g. Even at a high current density of 2000 mA g, the electrode can still deliver a specific capacity of 423.3 mA h g, demonstrating superior electrochemical properties for LIBs. In addition, the obtained 3D hierarchical MnCoO porous dumbbells also display good oxygen evolution reaction activity with an overpotential of 426 mV at a current density of 10 mA cm and a Tafel slope of 93 mV dec.
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http://dx.doi.org/10.1021/acsami.7b19719DOI Listing
March 2018

Transition-Metal-Triggered High-Efficiency Lithium Ion Storage via Coordination Interactions with Redox-Active Croconate in One-Dimensional Metal-Organic Anode Materials.

ACS Appl Mater Interfaces 2018 Feb 9;10(7):6398-6406. Epub 2018 Feb 9.

College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (MOE), ‡State Key Laboratory of Elemento-Organic Chemistry, and §Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University , Tianjin 300071, China.

Coordination polymers (CPs) have powerful competence as anode materials for lithium-ion batteries (LIBs) owing to their structural diversity, tunable functionality, and facile and mild synthetic conditions. Here, we show that two isostructural one-dimensional croconate-based CPs, namely, [M(CO)(HO)] (M = Mn for 1 and Co for 2; CO = croconate dianion), can work as high-performance electrode materials for rechargeable LIBs. By means of the coordination between the redox-active transition metal ion and the ligand, the anode materials were stable in the electrolyte and showed high capacities, impressive rate capabilities, and excellent cycling performance during the discharging/charging processes. The chain-based supramolecular structures of the CPs also make them stand out from a crowd of porous three-dimensional molecular materials due to their free channels between the chains for lithium ion diffusion. When tested in a voltage window of 0.01-2.4 V at 100 mA g, CPs 1 and 2 demonstrated high discharge specific capacities of 729 and 741 mA h g, respectively. The synergistical redox reactions on both metal centers and the organic moieties play a crucial role in the high electrochemical performance of CPs 1 and 2. After undergoing elevated discharging/charging rates to 2 A g, the electrodes could finally recover their capabilities as those in the initial stage when the current rate was back to 100 mA g, indicating excellent rate performance and outstanding cycling stabilities of the materials.
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http://dx.doi.org/10.1021/acsami.7b18758DOI Listing
February 2018

Ultrasmall Sn nanoparticles embedded in spherical hollow carbon for enhanced lithium storage properties.

Chem Commun (Camb) 2018 Jan;54(10):1205-1208

College of Chemistry & Environmental Science, Key Laboratory of Analytical Science and Technology of Hebei Province, Hebei University, Baoding 071002, China.

We here report on the preparation and Li-ion battery anode application of ultrasmall Sn nanoparticles (∼5 nm) uniformly embedded in spherical hollow carbon. The novel Sn-C composite shows a high Li-storage capacity (743 mA h g at 0.5 A g) with unprecedentedly high cyclic stability (92.1% capacity retention after 6000 cycles at 4 A g).
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http://dx.doi.org/10.1039/c7cc09095aDOI Listing
January 2018

Oxygen Vacancies Dominated NiS /CoS Interface Porous Nanowires for Portable Zn-Air Batteries Driven Water Splitting Devices.

Adv Mater 2017 Dec 2;29(47). Epub 2017 Nov 2.

Department of Materials Science & Engineering, College of Engineering, Peking University, Beijing, 100871, China.

The development of highly active and stable oxygen evolution reaction (OER) electrocatalysts is crucial for improving the efficiency of water splitting and metal-air battery devices. Herein, an efficient strategy is demonstrated for making the oxygen vacancies dominated cobalt-nickel sulfide interface porous nanowires (NiS /CoS -O NWs) for boosting OER catalysis through in situ electrochemical reaction of NiS /CoS interface NWs. Because of the abundant oxygen vacancies and interface porous nanowires structure, they can catalyze the OER efficiently with a low overpotential of 235 mV at j = 10 mA cm and remarkable long-term stability in 1.0 m KOH. The home-made rechargeable portable Zn-air batteries by using NiS /CoS -O NWs as the air-cathode display a very high open-circuit voltage of 1.49 V, which can maintain for more than 30 h. Most importantly, a highly efficient self-driven water splitting device is designed with NiS /CoS -O NWs as both anode and cathode, powered by two-series-connected NiS /CoS -O NWs-based portable Zn-air batteries. The present work opens a new way for designing oxygen vacancies dominated interface nanowires as highly efficient multifunctional electrocatalysts for electrochemical reactions and renewable energy devices.
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http://dx.doi.org/10.1002/adma.201704681DOI Listing
December 2017

In situ synthesis of Bi nanoflakes on Ni foam for sodium-ion batteries.

Chem Commun (Camb) 2017 Dec;54(1):38-41

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300071, P. R. China.

We report a facile method to in situ synthesize Bi nanoflakes on Ni foam (Bi/Ni) via a replacement reaction, which can directly work as an anode for sodium-ion batteries (SIBs) without further treatment. The integrated nanoflake structure of the Bi/Ni effectively accommodates the dramatic volume changes of Bi during cycling, and favors both electron and Na transport through the electrode. This ensures high cycling performance and good rate capability. The sodiation/desodiation of Bi is revealed to be composed of two successive steps: Bi ↔ NaBi and NaBi ↔ NaBi. This facile strategy will encourage more investigations into the design and synthesis of integrated electrodes for high-performance SIBs.
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http://dx.doi.org/10.1039/c7cc08341fDOI Listing
December 2017

Rechargeable aqueous zinc-manganese dioxide batteries with high energy and power densities.

Nat Commun 2017 09 1;8(1):405. Epub 2017 Sep 1.

Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) and State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China.

Although alkaline zinc-manganese dioxide batteries have dominated the primary battery applications, it is challenging to make them rechargeable. Here we report a high-performance rechargeable zinc-manganese dioxide system with an aqueous mild-acidic zinc triflate electrolyte. We demonstrate that the tunnel structured manganese dioxide polymorphs undergo a phase transition to layered zinc-buserite on first discharging, thus allowing subsequent intercalation of zinc cations in the latter structure. Based on this electrode mechanism, we formulate an aqueous zinc/manganese triflate electrolyte that enables the formation of a protective porous manganese oxide layer. The cathode exhibits a high reversible capacity of 225 mAh g and long-term cyclability with 94% capacity retention over 2000 cycles. Remarkably, the pouch zinc-manganese dioxide battery delivers a total energy density of 75.2 Wh kg. As a result of the superior battery performance, the high safety of aqueous electrolyte, the facile cell assembly and the cost benefit of the source materials, this zinc-manganese dioxide system is believed to be promising for large-scale energy storage applications.The development of rechargeable aqueous zinc batteries are challenging but promising for energy storage applications. With a mild-acidic triflate electrolyte, here the authors show a high-performance Zn-MnO battery in which the MnO cathode undergoes Zn (de)intercalation.
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http://dx.doi.org/10.1038/s41467-017-00467-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5581336PMC
September 2017