Developments of nanostructured transition metal dichalcogenides （TMDs） materials as novel electrocatalyst candidates for oxygen reduction reaction （ORR） is a new strategy to promote the developments of non-preciou...Developments of nanostructured transition metal dichalcogenides （TMDs） materials as novel electrocatalyst candidates for oxygen reduction reaction （ORR） is a new strategy to promote the developments of non-precious metal ORR catalysts. In this work, a three-dimensional （3D） hybrid of rosebud-like MoSe2 nanostructures supported on reduced graphene oxide （rGO） nanosheets was successfully synthesized through a facile hydrothermal strategy. The prepared MoSe2@rGO hybrid nanostructure showed enhanced electrocatalytic activity for the ORR in alkaline medium compared to that of the pure MoSe2, rGO, and their simple physical mixture, which could benefit from the excellent oxygen adsorption ability of the abundantly exposed active edge sites of the ultrathin MoSe2 layers, the conductivity and aggregation-limiting effect of the rGO platform, as well as the unique 3D rosebud-like architecture of the hybrid material. The electrocatalytic activity of the MoSe2@rGO hybrid towards ORR was comparable to that of com- inertial Pt/C catalysts. And the promoted reaction was revealed to involve a nearly four-electron-dominated ORR process by analysis of the obtained Koutecky- Levich plots. The scanning electrochemical microscopy （SECM） technique, with the advantages of investigating of the local catalytic activity of samples with high spatial resolution and simultaneously evaluating activities of different catalysts in a single experiment, was further applied to investigate the local ORR electrocatalytic activity of MoSe2@rGO and compare it with those of other catalyst samples through applying different sample potentials. The excellent stability and methanol tolerance of the 3D nanostructured MoSe2@rGO hybrid against methanol further prove the 3D nanostructured MoSe2@rGO hybrid as a promising ORR electrocatalyst in alkaline solution for potential applications in fuel cells and metal-air batteries.展开更多
We reported a facile and robust one-pot wet chemistry strategy to achieve the growth of uniform three dimensional（3D） MoSe_2 ultrathin nanostructures on graphene nanosheets to form high quality MoSe_2/rGO hybrid nan...We reported a facile and robust one-pot wet chemistry strategy to achieve the growth of uniform three dimensional（3D） MoSe_2 ultrathin nanostructures on graphene nanosheets to form high quality MoSe_2/rGO hybrid nanostructures.Owing to the graphene as a support,it can significantly prevent the aggregation of MoSe_2 and the distribution of MoSe_2 on graphene was highly uniform.Importantly,due to the unique structures,the as-harvested MoSe_2/rGO hybrid exhibited excellent electrochemical performance as anode materials for sodium-ion battery（SIB）.When evaluated in a half cell system,the MoSe_2/rGO hybrid nanostructures could deliver a capacity of 200.2 mA h g^（-1） at8 A g^（-1） and maintain a capacity of 230.1 mA h g^（-1） over 100 cycles at 5 A g^（-1）.When coupled with Na_3V_2（PO_4）_3 cathode in a full cell system,the material could deliver a discharge capacity of 363.1 mA h g^（-1） at the current density of 0.5 A g^（-1）.Moreover,a discharge capacity of 56.4 mA h g^（-1） could be achieved even at a high current density of 10 A g^（-1）,which clearly suggested the high power capability of MoSe_2/rGO hybrid nanostructures for sodium ion energy storage.展开更多
The lithium polysulfide shuttle and sluggish sulfur reaction kinetics still pose significant challenges to lithium-sulfur(Li-S)batteries.The functional plane of Fe-MoSe_(2)@r GO nanohybrid with abundant defects has be...The lithium polysulfide shuttle and sluggish sulfur reaction kinetics still pose significant challenges to lithium-sulfur(Li-S)batteries.The functional plane of Fe-MoSe_(2)@r GO nanohybrid with abundant defects has been designed and applied in Li-S batteries to develop the functional separator and multi-layer sulfur cathode.The cell with a functional separator exhibits a retention capacity of 462 m Ah g^(-1)after the 1000th at 0.5 C and 516 m Ah g^(-1)after the 600th at 0.3 C.Even at low electrolyte conditions(7.0μL_(mgsulfur)^(-1)and 15μL_(mgsulfur)^(-1))under high sulfur loadings(3.46 mg cm^(-2)and 3.73 mg cm^(-2)),the cell still presents high reversible discharge capacities 679 and 762 m Ah g^(-1)after 70 cycles,respectively.Further,at sulfur loadings up to 8.26 and 5.2 mg cm^(-2),the cells assembled with the bi-layers sulfur cathode and the tri-layers sulfur cathode give reversible capacities of 3.3 m Ah cm^(-2)after the 100th cycle and 3.0 m Ah cm^(-2)after the 120th cycle,respectively.This research not only demonstrates that the FeMoSe_(2)@r GO functional plane is successfully designed and applied in Li-S batteries with superior electrochemical performances but also paves the novel way for developing a unique multi-layer cathode technique to enhance and advance the electrochemical behavior of Li-S cells at a high-sulfur-loading cathode under lean electrolyte/sulfur(E/S)ratio.展开更多
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 21105079 and 21405119）, the Fundamental Research Funds for the Central Universities of China （Nos. 0109-1191320016 and cxtd2015003）, the Scientific Research Foundation for the Returned Overseas Chinese Scholars by the State Education Ministry of China, and the Interna- tional Science and Technology Cooperation and Exchange Program of Shaanxi Province of China （No. 2016KW-064）. Yaping Du gratefully acknowledgesthe financial support from the start-up funding from Xi＇an Jiaotong University, the Fundamental Research Funds for the Central Universities of China （No. 2015qngz12）, and the the National Natural Science Foundation of China （Nos. 21522106 and 21371140）.
文摘Developments of nanostructured transition metal dichalcogenides （TMDs） materials as novel electrocatalyst candidates for oxygen reduction reaction （ORR） is a new strategy to promote the developments of non-precious metal ORR catalysts. In this work, a three-dimensional （3D） hybrid of rosebud-like MoSe2 nanostructures supported on reduced graphene oxide （rGO） nanosheets was successfully synthesized through a facile hydrothermal strategy. The prepared MoSe2@rGO hybrid nanostructure showed enhanced electrocatalytic activity for the ORR in alkaline medium compared to that of the pure MoSe2, rGO, and their simple physical mixture, which could benefit from the excellent oxygen adsorption ability of the abundantly exposed active edge sites of the ultrathin MoSe2 layers, the conductivity and aggregation-limiting effect of the rGO platform, as well as the unique 3D rosebud-like architecture of the hybrid material. The electrocatalytic activity of the MoSe2@rGO hybrid towards ORR was comparable to that of com- inertial Pt/C catalysts. And the promoted reaction was revealed to involve a nearly four-electron-dominated ORR process by analysis of the obtained Koutecky- Levich plots. The scanning electrochemical microscopy （SECM） technique, with the advantages of investigating of the local catalytic activity of samples with high spatial resolution and simultaneously evaluating activities of different catalysts in a single experiment, was further applied to investigate the local ORR electrocatalytic activity of MoSe2@rGO and compare it with those of other catalyst samples through applying different sample potentials. The excellent stability and methanol tolerance of the 3D nanostructured MoSe2@rGO hybrid against methanol further prove the 3D nanostructured MoSe2@rGO hybrid as a promising ORR electrocatalyst in alkaline solution for potential applications in fuel cells and metal-air batteries.
基金supported by the start-up funding from Xi'an Jiaotong University,the Fundamental Research Funds for the Central Universities(2015qngzl2)the China National Funds for Excellent Young Scientists(21522106)the National Natural Science Foundation of China(21371140)
文摘We reported a facile and robust one-pot wet chemistry strategy to achieve the growth of uniform three dimensional（3D） MoSe_2 ultrathin nanostructures on graphene nanosheets to form high quality MoSe_2/rGO hybrid nanostructures.Owing to the graphene as a support,it can significantly prevent the aggregation of MoSe_2 and the distribution of MoSe_2 on graphene was highly uniform.Importantly,due to the unique structures,the as-harvested MoSe_2/rGO hybrid exhibited excellent electrochemical performance as anode materials for sodium-ion battery（SIB）.When evaluated in a half cell system,the MoSe_2/rGO hybrid nanostructures could deliver a capacity of 200.2 mA h g^（-1） at8 A g^（-1） and maintain a capacity of 230.1 mA h g^（-1） over 100 cycles at 5 A g^（-1）.When coupled with Na_3V_2（PO_4）_3 cathode in a full cell system,the material could deliver a discharge capacity of 363.1 mA h g^（-1） at the current density of 0.5 A g^（-1）.Moreover,a discharge capacity of 56.4 mA h g^（-1） could be achieved even at a high current density of 10 A g^（-1）,which clearly suggested the high power capability of MoSe_2/rGO hybrid nanostructures for sodium ion energy storage.
基金the support from the National Natural Science Foundation of China(No.21373189)the Science and Technology Department of Henan Province(No.212102210586)the Top-Notch Talents Program of Henan Agricultural University(No.30501035)。
文摘The lithium polysulfide shuttle and sluggish sulfur reaction kinetics still pose significant challenges to lithium-sulfur(Li-S)batteries.The functional plane of Fe-MoSe_(2)@r GO nanohybrid with abundant defects has been designed and applied in Li-S batteries to develop the functional separator and multi-layer sulfur cathode.The cell with a functional separator exhibits a retention capacity of 462 m Ah g^(-1)after the 1000th at 0.5 C and 516 m Ah g^(-1)after the 600th at 0.3 C.Even at low electrolyte conditions(7.0μL_(mgsulfur)^(-1)and 15μL_(mgsulfur)^(-1))under high sulfur loadings(3.46 mg cm^(-2)and 3.73 mg cm^(-2)),the cell still presents high reversible discharge capacities 679 and 762 m Ah g^(-1)after 70 cycles,respectively.Further,at sulfur loadings up to 8.26 and 5.2 mg cm^(-2),the cells assembled with the bi-layers sulfur cathode and the tri-layers sulfur cathode give reversible capacities of 3.3 m Ah cm^(-2)after the 100th cycle and 3.0 m Ah cm^(-2)after the 120th cycle,respectively.This research not only demonstrates that the FeMoSe_(2)@r GO functional plane is successfully designed and applied in Li-S batteries with superior electrochemical performances but also paves the novel way for developing a unique multi-layer cathode technique to enhance and advance the electrochemical behavior of Li-S cells at a high-sulfur-loading cathode under lean electrolyte/sulfur(E/S)ratio.
