Li-rich layered oxide(LLO),e.g.,Li_(1.12)[Mn_(0.56)Ni_(0.16)Co_(0.08)]O_(2)(LRMO),is considered as a promising cathode material due to its superior Li-storage capability.However,the poor cycling stability and large vo...Li-rich layered oxide(LLO),e.g.,Li_(1.12)[Mn_(0.56)Ni_(0.16)Co_(0.08)]O_(2)(LRMO),is considered as a promising cathode material due to its superior Li-storage capability.However,the poor cycling stability and large voltage decay,which are related to the phase transition,limit its industrialization process.Herein,a Mo-doped LRMO(Li_(1.12)[Mn_(0.56)Ni_(0.16)Co_(0.08)]_(0.98)Mo_(0.02)O_(2),LRMO-Mo2.0%)was successfully synthesized via a simple combination of co-precipitation with high-temperature calcination for solving the mentioned above-disadvantages.Compared with the pristine counterpart,the as-prepared LRMO-Mo2.0%shows more excellent electrochemical performance in terms of rate capability(reversible capacity of 118 mA·h·g^(−1) at 5 C),cyclic ability(94.3%capacity retention after 100 cycles at 0.2 C)and discharge midpoint voltage decay(0.11 V after 100 cycles).Systematic investigation of structural evolution and electrochemical kinetics elucidate that the synergic effect of robust oxygen framework and layered/spinel heterostructure is the key to its performance improvement.Such synergy helps to stabilize the layered structure by curbing the structural transformation and oxygen escaping during the electrochemical cycling.This work paved the way for the simple and efficient preparation of highly stable LLO cathode materials.展开更多
With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to...With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.展开更多
Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate(H*)is impressive for hydrogen evolution reaction(HER)catalysis.Herein,we show that vertically mounting two-dimensional(2D)laye...Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate(H*)is impressive for hydrogen evolution reaction(HER)catalysis.Herein,we show that vertically mounting two-dimensional(2D)layered molybdenum disulfide(MoS_(2))nanosheets on 2D nonlayered dimolybdenum carbide(Mo_(2)C)nanomeshes to form a hierarchical heterostructure largely accelerates the HER kinetics in acidic electrolyte due to the weakening adsorption strength of H*on 2D Mo_(2)C nanomeshes.Our hierarchical MoS2/Mo2C heterostructure therefore gives a decrease of overpotential for up to 500 mV at-10 mA·cm^(-2)and an almost 200-fold higher kinetics current density compared with the pristine Mo2C nanomeshes and maintains robust stability with a small drop of overpotential for only 16 mV upon 5,000 cycles.We further rationalize this finding by theoretical calculations and find an optimized adsorption free energy of H*,identifying that the MoS_(2)featuring strong H*desorption plays a key role in weakening the strong binding of Mo_(2)C with H*and therefore improves the intrinsic HER activity on active C sites of Mo_(2)C.This present finding shines the light on the rational design of heterostructured catalysts with synergistic geometry.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.51964017,Grant No.51874151)the Jiangxi Provincial Natural Science Foundation(Grant No.20212BAB214004)+1 种基金the Jiangxi Provincial Education Office Natural Science Fund Project(Grant No.GJJ201413)the Jiangxi University of Science and Technology College Student Innovation and Entrepreneurship Training Program Support Project(Grant No.DC2019-042).
文摘Li-rich layered oxide(LLO),e.g.,Li_(1.12)[Mn_(0.56)Ni_(0.16)Co_(0.08)]O_(2)(LRMO),is considered as a promising cathode material due to its superior Li-storage capability.However,the poor cycling stability and large voltage decay,which are related to the phase transition,limit its industrialization process.Herein,a Mo-doped LRMO(Li_(1.12)[Mn_(0.56)Ni_(0.16)Co_(0.08)]_(0.98)Mo_(0.02)O_(2),LRMO-Mo2.0%)was successfully synthesized via a simple combination of co-precipitation with high-temperature calcination for solving the mentioned above-disadvantages.Compared with the pristine counterpart,the as-prepared LRMO-Mo2.0%shows more excellent electrochemical performance in terms of rate capability(reversible capacity of 118 mA·h·g^(−1) at 5 C),cyclic ability(94.3%capacity retention after 100 cycles at 0.2 C)and discharge midpoint voltage decay(0.11 V after 100 cycles).Systematic investigation of structural evolution and electrochemical kinetics elucidate that the synergic effect of robust oxygen framework and layered/spinel heterostructure is the key to its performance improvement.Such synergy helps to stabilize the layered structure by curbing the structural transformation and oxygen escaping during the electrochemical cycling.This work paved the way for the simple and efficient preparation of highly stable LLO cathode materials.
基金We acknowledged the financial support from the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)the National Natural Science Foundation of China(Nos.61725107,11622437,61674171,11974422,61761166009,and 61888102)+3 种基金the National Key Research&Development Projects of China(Nos.2016YFA0202301,2019YFA0308000,and 2018YFE0202700)the Fundamental Research Funds for the Central Universities,China and the Research Funds of Renmin University of China(Nos.16XNLQ01 and 19XNQ025)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB30000000 and XDB28000000)Calculations were performed at the Physics Lab of High-Performance Computing of Renmin University of China and Shanghai Supercomputer Center.
文摘With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.
基金The authors thank the supports from the Fundamental Research Funds for the Central Universities(No.40120631)the Zhejiang Provincial Natural Science Foundation(Nos.LQ22B060003 and LY20E020004)+1 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.2020YQ005)the Research Foundation of Talented Scholars of Zhejiang A&F University(No.2020FR069).
文摘Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate(H*)is impressive for hydrogen evolution reaction(HER)catalysis.Herein,we show that vertically mounting two-dimensional(2D)layered molybdenum disulfide(MoS_(2))nanosheets on 2D nonlayered dimolybdenum carbide(Mo_(2)C)nanomeshes to form a hierarchical heterostructure largely accelerates the HER kinetics in acidic electrolyte due to the weakening adsorption strength of H*on 2D Mo_(2)C nanomeshes.Our hierarchical MoS2/Mo2C heterostructure therefore gives a decrease of overpotential for up to 500 mV at-10 mA·cm^(-2)and an almost 200-fold higher kinetics current density compared with the pristine Mo2C nanomeshes and maintains robust stability with a small drop of overpotential for only 16 mV upon 5,000 cycles.We further rationalize this finding by theoretical calculations and find an optimized adsorption free energy of H*,identifying that the MoS_(2)featuring strong H*desorption plays a key role in weakening the strong binding of Mo_(2)C with H*and therefore improves the intrinsic HER activity on active C sites of Mo_(2)C.This present finding shines the light on the rational design of heterostructured catalysts with synergistic geometry.
