Transition metal oxides (TMOs) based compounds are recognized as high-energy anodes in next-generation lithium-ion batteries (LIBs) due to their extremely high theoretical capacity. However, the lower intrinsic conductivity , fast fading cyclic stability and dramatic volume expansion during discharge/charge processes greatly hinder the practical application of TMOs as anodes in LIBs. In this study, we have designed and constructed MoO 3 /ZnCo 2 O 4 QDs@C@rGO/MoO 3 (denoted as GMZCO) sandwich-structured hybrid nanocomposites via an effective route, and have proposed the formation mechanism of this unique nanostructured composite on the basis of the systematic results of the microstructures. Due to the unique sandwich structure and the synergistic enhancement effect of the ZnCo 2 O 4 QDs , α-MoO 3 and rGO, the as-constructed GMZCO exhibits the superior electrochemical performances when used as anode for LIBs. The obtained GMZCO can maintain high capacity of 1281 mAh g −1 at 0.2 A g −1 after 300 cycles, and can deliver as high as specific capacity of 913 mAh g −1 at 1 A g −1 after 500 cycles, revealing the higher capacity and excellent cyclic stability. What deserves to be mentioned most is that GMZCO can keep a capacity of 541 mAh g −1 after 1400 cycles even at higher current density of 3 A g −1 , having outstanding rate capability. This work paves a novel approach for design TMOs with unique microstructures as a promising anode for the high-performances LIBs.
Chemically integrated hybrid quantum dots ZnCo 2 O 4 /reduced graphene oxide (QDs ZCO/rGO) sheets nanocomposites are synthesized through polyol processes. rGO sheets grow and interweave to form basic skeletons. Ultrafine ZCO particles with a size of around 3.66 nm grow and embed on both sides of the rGO sheets, and the rGO sheets restrain the reunion of ZCO nanoparticles . The existence of rGO sheets and ZCO nanoparticles can engender the mutual synergistic effects so that hybrid QDs ZCO/rGO electrodes exhibit the excellent electrochemical properties . Owing to this special nanoparticles-on-sheets structure, the hybrid QDs ZCO/rGO electrodes exhibit an excellent initial discharge capacity for rechargeable lithium-ion batteries (1325.9 mAh g −1 at the current density of 200 mA g −1 ), high rate stability (532.3/566.1 mAh g −1 at 4000 mA g −1 ) and outstanding electrochemical cyclic stability (657.6/668.2 mAh g −1 at 2000 mA g −1 after 2000 cycles with a capacity retention of 68.6%). For full-cells, high initial reversible discharging capacity (646 mAh g −1 at 200 mA g −1 ) and good cyclic stability (514 mAh g −1 at 200 mA g −1 after 100 cycles) are obtained. The superior performance of the as-prepared electrodes is ascribed to the advantage of nano-sized particles. With the successful synthesis of hybrid QDs ZCO/rGO nanocomposites, the facile synthetic route and unique growth of nanostructuring method can be extended to high electrochemical performance electrodes for commercial lithium-ion batteries.
Xuan Li,Li Liu,Xue Dong,Guanhui Zhao,Yueyuan Li,Juncong Miao,Jinglong Fang,Min Cui,Qin Wei,Wei Cao
A sensitive dual mode competitive electrochemical immunosensor for the detection of B-type natriuretic peptide (BNP) was successfully fabricated, which based on differential pulse voltammetry (DPV) and amperometric i-t curve response modes. Polyaniline (PAN) and tin dioxide (SnO 2 ) were loaded on graphene sheets (GS), which could effectively promote the electron transfer process, thereby amplifying the current signal and increasing the sensitivity of the immunosensor. To promote biocompatibility, gold nanoparticles (Au) were incorporated on GS/SnO 2 /PAN (GS/SnO 2 /PAN-Au). GS/SnO 2 /PAN-Au complex was gotten to act as the platform which could provide a clearly DPV signals. N-doped carbon nanotubes (N-CNTs) embellished by ZnCo 2 O 4 quantum dots (ZnCo 2 O 4 /N-CNTs) with excellent catalytic properties for the reduction of H 2 O 2 was gotten to act as the label of the antibody-BNP (Ab), providing an obviously current signal through amperometric i-t curve method. A large quantity of BNP could be stable loaded in the modified electrode via GS/SnO 2 /PAN-Au with excellent electrical conductivity and good biocompatibility , which could compete with target-BNP to combine Ab that labelled by ZnCo 2 O 4 /N-CNTs. Under the optimum conditions, the immunosensor exhibited remarkable analytical performance of a linear range from 0.01 pg/mL to 1 ng/mL with a detection limit of 3.4 fg/mL for quantitative detection of BNP (S/N = 3). This method was able to become a universal strategy for other biological detection.
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