Chencheng Sun

Hybrid NiCo2S4@MnO2 heterostructures for high-performance supercapacitor electrodes

Using a simple hydrothermal route coupled with a carbonization treatment, one-dimensional NiCo2S4@MnO2 heterostructures have been fabricated successfully. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) measurements showed that MnO2 nanoflakes uniformly wrapped around the surface of NiCo2S4 nanotubes and formed core–shell heterostructured nanotubes, which combine the advantages of both NiCo2S4 such as excellent cycle stability and MnO2 such as high capacity. Serving as a supercapacitor electrode, the NiCo2S4@MnO2 heterostructures possess a remarkable specific capacitance (1337.8 F g−1 at the current density of 2.0 A g−1) and excellent cycling stability (retaining 82% after 2000 cycles) due to the synergistic effects of NiCo2S4 and MnO2. These unique nanoarchitectures demonstrate potential applications in energy storage electrodes and may inspire researchers to continue to focus on heterostructured materials.

MOF-directed templating synthesis of a porous multicomponent dodecahedron with hollow interiors for enhanced lithium-ion battery anodes

The high performance of lithium-ion battery (LIB) electrodes relies largely on the meticulous design of hierarchical nanostructures with optimal balance between superior electrochemical properties and conductivity. Herein, we present a facile and cost-effective solvothermal method to fabricate a porous NiCo2O4/NiO hollow dodecahedron using zeolitic imidazolate framework-67 (ZIF-67) as both a precursor and a self-sacrificing template. Accurate control between the template etching and the precipitation of the shells is crucial to the preparation of the perfect nanocages. Serving as LIB anode materials, such metal–organic framework derived multiple transition metal oxides demonstrate a high reversible capacity of 1535 mA h g−1 at 0.2 A g−1 and a good cycling stability (97.2% retention after 100 cycles). The presented strategy represents a general route to synthesize various hierarchically interconnected and porous nanostructures of mixed transition metal oxides which are promising for a range of applications.

Metal-organic framework derived CoSe2 nanoparticles anchored on carbon fibers as bifunctional electrocatalysts for efficient overall water splitting

The development of efficient, low-cost, stable, non-noble-metal electrocatalysts for water splitting, particularly those that can catalyze both the hydrogen evolution reaction (HER) at the cathode and oxygen evolution reaction (OER) at the anode, is a challenge. We have developed a facile method for synthesizing CoSe2 nanoparticles uniformly anchored on carbon fiber paper (CoSe2/CF) via pyrolysis and selenization of in situ grown zeolitic imidazolate framework-67 (ZIF-67). CoSe2/CF shows high and stable catalytic activity in both the HER and OER in alkaline solution. At a low cell potential, i.e., 1.63 V, a water electrolyzer equipped with two CoSe2/CF electrodes gave a water-splitting current of 10 mA·cm−2. At a current of 20 mA·cm−2, it can operate without degradation for 30 h. This study not only offers a cost-effective solution for water splitting but also provides a new strategy for developing various catalytic nanostructures by changing the metal–organic framework precursors.

Template Synthesis of Shape-Tailorable NiS2 Hollow Prisms as High-Performance Supercapacitor Materials

Uniform NiS2 hollow nanoprisms have been controllably synthesized by a facial sacrificial template method including two-step refluxed reactions. The morphology of the hollow NiS2 prisms can be easily tailored by the low cost nickel complex template. With unique hollow structure, efficient electron, and ion transport pathway as well as single crystal structure, the NiS2 hollow prisms electrode exhibits excellent pseudocapacitive performance in LiOH electrolyte. It can deliver a specific capacitance of 1725 F g(-1) at a current density of 5 A g(-1) and 1193 F g(-1) even at a current density of 40 A g(-1). Furthermore, the materials also present an amazing cycling stability, that is, the specific capacitance can increase from 1367 F g(-1) to 1680 F g(-1) after 10,000 cycles of charge-discharge at the current density of 20 A g(-1).

Phase-controlled synthesis of α-NiS nanoparticles confined in carbon nanorods for high performance supercapacitors

A facile and phase-controlled synthesis of α-NiS nanoparticles (NPs) embedded in carbon nanorods (CRs) is reported by in-situ sulfurating the preformed Ni/CRs. The nanopore confinement by the carbon matrix is essential for the formation of α-NiS and preventing its transition to β-phase, which is in strong contrast to large aggregated β-NiS particles grown freely without the confinement of CRs. When used as electrochemical electrode, the hybrid electrochemical charge storage of the ultrasmall α-NiS nanoparticels dispersed in CRs is benefit for the high capacitor (1092, 946, 835, 740 F g−1 at current densities of 1, 2, 5, 10 A g−1, respectively.). While the high electrochemical stability (approximately 100% retention of specific capacitance after 2000 charge/discharge cycles) is attributed to the supercapacitor-battery electrode, which makes synergistic effect of capacitor (CRs) and battery (NiS NPs) components rather than a merely additive composite. This work not only suggests a general approach for phase-controlled synthesis of nickel sulfide but also opens the door to the rational design and fabrication of novel nickel-based/carbon hybrid supercapacitor-battery electrode materials.

CuO/Cu2O porous composites: shape and composition controllable fabrication inherited from metal organic frameworks and further application in CO oxidation

CuO/Cu2O porous composites with adjustable composition and various morphologies, including cube, octahedron, rod and wire, have been successfully achieved. These structures are inherited from metal organic frameworks formed by Cu and trimesic acid and can be regulated under mild conditions. While tested in CO oxidation, these porous composites exhibited a high performance.

Controlled synthesis of zinc cobalt sulfide nanostructures in oil phase and their potential applications in electrochemical energy storage

A unique controlled synthesis of zinc cobalt sulfide nanostructures is obtained by a facile oil phase approach. Nanoartichokes composed of self-assembled nanosheets and nanoparticles have been fabricated by using different sulfur sources. The application of such nanomaterials is demonstrated as electrodes for supercapacitors and lithium-ion batteries. Serving as lithium-ion battery electrodes, the ZnxCo1−xS nanoartichokes deliver a higher specific capacity of 750 mA h g−1 during the 100th cycle as compared to only 220 mA h g−1 for nanoparticles. In supercapacitor tests, the ZnxCo1−xS nanoartichokes possess an improved specific capacitance (486.2 F g−1 at a current density of 2.0 A g−1) and excellent cycling stability (retaining 86.4% after 2000 cycles), both of which are much higher than those of nanoparticles (e.g. 406.7 F g−1 and 73.3%). This effective nanostructure design of ternary transition metal sulfides could provide a promising method to construct high-performance materials for energy and environment applications.

Graphene and cobalt phosphide nanowire composite as an anode material for high performance lithium-ion batteries

The synthesis of a composite of cobalt phosphide nanowires and reduced graphene oxide (denoted CoP/RGO) via a facile hydrothermal method combined with a subsequent annealing step is reported. The resulting composite presents large specific surface area and enhanced conductivity, which can effectively facilitate charge transport and accommodates variations in volume during the lithiation/de-lithiation processes. As a result, the CoP/RGO nanocomposite manifests a high reversible specific capacity of 960 mA·h·g–1 over 200 cycles at a current density of 0.2 A·g–1 (297 mA·h·g–1 over 10,000 cycles at a current density of 20 A·g–1) and excellent rate capability (424 mA·h·g–1 at a current density of 10 A·g–1).

Hierarchical carbon@Ni3S2@MoS2 double core–shell nanorods for high-performance supercapacitors

Hierarchical carbon@Ni3S2@MoS2 (C@Ni3S2@MoS2) double core–shell nanorods have been synthesized by a facile hydrothermal method using highly conductive carbon/Ni (C/Ni) nanorods as both the precursor and template. As supercapacitor electrodes, the C@Ni3S2@MoS2 nanorods deliver a specific capacitance as high as 1544 F g−1 at a current density of 2 A g−1 with excellent cycling stability (retaining 92.8% of the capacitance after 2000 cycles at a current density of 20 A g−1). The C/Ni nanorods as the backbone played crucial roles in enhancing the rate performance of the device, in the meanwhile, interconnected MoS2 nanosheets on the shell provided numerous accessible surfaces and contacts with the electrolyte. Our work demonstrated an effective design of robust hierarchical double core/shell nanostructures, which could provide a general and promising approach to fabricate high-performance materials for energy storage applications.

Nanowires assembled from MnCo2O4@C nanoparticles for water splitting and all-solid-state supercapacitor

The rational design of earth-abundant catalysts with excellent water splitting activities is important to obtain clean fuels for sustainable energy devices. In this study, mixed transition metal oxide nanoparticles encapsulated in nitrogendoped carbon (denoted as AB2O4@NC) were developed using a one-pot protocol, wherein a metal–organic complex was adopted as the precursor. As a proof of concept, MnCo2O4@NC was used as an electrocatalyst for water oxidation, and demonstrated an outstanding electrocatalytic activity with low overpotential to achieve a current density of 10 mA·cm−1 (η10 = 287 mV), small Tafel slope (55 mV·dec−1), and high stability (96% retention after 20 h). The excellent electrochemical performance benefited from the synergistic effects of the MnCo2O4 nanoparticles and nitrogen-doped carbon, as well as the assembled mesoporous nanowire structure. Finally, a highly stable all-solid-state supercapacitor based on MnCo2O4@NC was demonstrated (1.5% decay after 10,000 cycles).