Xiaoshu Zhu

Co3S4 porous nanosheets embedded in graphene sheets as high-performance anode materials for lithium and sodium storage

Co3S4 porous nanosheets embedded in flexible graphene sheets have been synthesized through a simple freeze-drying and subsequent hydrazine treatment process. The robust structural stability of the as-prepared three-dimensional sandwich-like Co3S4–PNS/GS composite affords improved rate performance and cycling stability for both lithium and sodium storage.

Kelp-derived hard carbons as advanced anode materials for sodium-ion batteries

Sodium-ion batteries (SIBs) have received much attention for scalable electrical energy storage because of the abundance and wide availability of sodium resources. However, it is still unclear whether carbon anodes can realize large-scale commercial application in SIBs as in lithium-ion batteries. Recently, great attention has been devoted to hard carbon which has been treated as a promising choice. Herein, we observe that the turbostratic lattice of kelp-derived hard carbon (KHC) is repeatedly expandable and shrinkable upon cycling, where the interlayer distance varies between 3.9 and 4.3 A. Such interlayer spacing dilation is highly reversible, giving rise to high rate capability (a stable capacity of 96 mA h g−1 at 1000 mA g−1) and excellent cycling performance (205 mA h g−1 after 300 cycles at 200 mA g−1). Furthermore, kelp-derived hard carbon exhibits a good specific capacity at potentials higher than 0.05 V, which make it an essentially dendrite-free anode for SIBs.

L-Lysine mediated synthesis of platinum nanocuboids and their electrocatalytic activity towards ammonia oxidation

Well-defined platinum nanocrystals with a cuboid-like shape (Pt nanocuboids) were synthesized in high yields by the simple hydrothermal reduction of Pt(II) precursors with formaldehyde (HCHO) solution in the presence of L-lysine and polyvinyl pyrrolidone (PVP). The influential effects of several important experimental parameters on the shape of Pt nanocrystals were systematically investigated, demonstrating that L-lysine and oxidative etching were critical to the morphological control and evolution of Pt nanocuboids. Due to the unique orientation and size effects, the as-prepared Pt nanocuboids exhibited significantly enhanced catalytic activity and stability towards the ammonia oxidation reaction (AOR) in comparison with commercial Pt black catalysts.

Direct electrochemistry of hemoglobin immobilized on the water-soluble phosphonate functionalized multi-walled carbon nanotubes and its application to nitric oxide biosensing.

The direct electron transfer and electrocatalysis of hemoglobin (Hb) immobilized on the phosphonate functionalized multi-walled carbon nanotubes (MWCNTs) are investigated. Fourier transform infrared (FT-IR) spectra, UV-vis spectra and cyclic voltammetry (CV) analyses reveal that the phosphonate functionalized MWCNTs have good biocompatibility for Hb immobilization, and promote the electron communication between Hb and electrode. The immobilized Hb shows a pair of redox peak with a formal potential of -406 ± 10 mV (vs. SCE) and the electrochemical behavior of Hb was a surface-controlled process in a pH 7.0 phosphate buffer solution. And the immobilized Hb can act in an electrocatalytic manner in the electrochemical reduction of nitric oxide (NO). Accordingly, an unmediated NO electrochemical biosensor is constructed. Under optimized experimental conditions, the NO electrochemical biosensor shows the fast response (less than 3s), the wide linear range (1.5 × 10(-7) to 2.7 × 10(-4)M) and the low detection limit (1.5 × 10(-8)M), which is attributed to the good mass transport, the large Hb loading per unit area and the fast electron transfer rate of Hb.

Proline-derived in situ synthesis of nitrogen-doped porous carbon nanosheets with encaged Fe2O3@Fe3C nanoparticles for lithium-ion battery anodes

The homogeneous incorporation of heteroatoms into two-dimensional C nanostructures, which leads to an increased chemical reactivity and electrical conductivity as well as enhanced synergistic catalysis as a conductive matrix to disperse and encapsulate active nanocatalysts, is highly attractive and quite challenging. In this study, by using the natural and cheap hydrotropic amino acid proline—which has remarkably high solubility in water and a desirable N content of ~12.2 wt.%—as a C precursor pyrolyzed in the presence of a cubic KCl template, we developed a facile protocol for the large-scale production of N-doped C nanosheets with a hierarchically porous structure in a homogeneous dispersion. With concomitantly encapsulated and evenly spread Fe2O3 nanoparticles surrounded by two protective ultrathin layers of inner Fe3C and outer onion-like C, the resulting N-doped graphitic C nanosheet hybrids (Fe2O3@Fe3C-NGCNs) exhibited a very high Li-storage capacity and excellent rate capability with a reliable and prolonged cycle life. A reversible capacity as high as 857 mAh•g–1 at a current density of 100 mA•g–1 was observed even after 100 cycles. The capacity retention at a current density 10 times higher—1,000 mA•g–1—reached 680 mAh•g–1, which is 79% of that at 100 mA•g–1, indicating that the hybrids are promising as anodes for advanced Li-ion batteries. The results highlight the importance of the heteroatomic dopant modification of the NGCNs host with tailored electronic and crystalline structures for competitive Li-storage features.

Encapsulating ionic liquids into POM-based MOFs to improve their conductivity for superior lithium storage

Developing advanced anode materials with multi-electron reaction, adequate charge transport, and suppressed volume changes is highly desirable in lithium storage. Both polyoxometalates (POMs) and metal–organic frameworks (MOFs) are attractive candidates for anode materials because of strong multi-electron redox properties of the former and high surface areas and controllable porosities of the latter. However, the easy dissolution of POMs in an electrolyte and the intrinsically poor conductivity of MOFs result in inferior rate performance and cycling capacity. In this paper, we skillfully encapsulate ionic liquids (ILs) into polyoxometalate-based metal–organic frameworks (POMOFs) to fabricate a series of ILs-functionalized POMOF crystals (denoted as POMs-ILs@MOFs), in which POMs are immobilized in MOF cages to avoid the leaching of POMs. Also, an enhanced conductivity is obtained by the modification of ILs. One of the POMs-ILs@MOFs crystals, PMo10V2-ILs@MIL-100, when used as the anode material, shows superior cycling stability and high rate capability, which is proven to be the best amongst those of all the reported MOF, POM, and POMOF crystal materials. The outstanding performances are attributed to the hybrid behavior of a battery and a supercapacitor, which results from the synergistic effects of ILs, POMs, and MOFs. Most importantly, we not only discover a series of new anode materials but also propose a new strategy to improve the conductivity of MOFs and POMOFs, which will guide the development of other electrode materials based on MOFs and POMOFs for lithium storage.

Novel nitrogen-doped reduced graphene oxide-bonded Sb nanoparticles for improved sodium storage performance

As a promising anode material for sodium-ion batteries, Sb has attracted considerable attention due to its high theoretical capacity (660 mA h g−1). However, it exhibits poor cycling stability because of its great volume change during sodium ion uptake and release processes. In order to solve this problem, using the ionic liquid Emim-dca as a nitrogen source, novel nitrogen-doped reduced graphene oxide-bonded Sb nanoparticles (Sb/N-rGO) are produced by ball-milling and subsequent pyrolysis treatment. As an anode material for sodium-ion batteries, Sb/N-rGO shows high capacity, excellent cycling stability, and high rate performance. A high reversible capacity of 304.8 mA h g−1 is achieved even at a current density of 5 A g−1. Even after 500 cycles, there is still 90.7% capacity retention (473.2 mA h g−1) at a current density of 0.1 A g−1. The superior sodium storage performance can be attributed to strong bonding between Sb and pyrrolic nitrogen in nitrogen-doped reduced graphene oxide. The facile synthesis strategy can potentially be applied to other anode materials for sodium-ion batteries.