Metal–organic frameworks (MOFs) with high surface areas and uniform microporous structures have shown potential application in many fields. Here we report a facial strategy to synthesize Fe2O3@NiCo2O4 porous nanocages by annealing core–shell Co3[Fe(CN)6]2@Ni3[Co(CN)6]2 nanocubes in air. The obtained samples have been systematically characterized by XRD, SEM, TEM and N2 adsorption–desorption analysis. The results show that the Fe2O3@NiCo2O4 porous nanocages have an average diameter of 213 nm and a shell thickness of about 30 nm. As anode materials for Li-ion batteries, the Fe2O3@NiCo2O4 porous nanocages exhibit a high initial discharge capacity of 1311.4 mA h g−1 at a current density of 100 mA g−1 (about 0.1 C). The capacity is retained at 1079.6 mA h g−1 after 100 cycles. The synergistic effect of the different components and the porous hollow structure contributes to the outstanding performance of the composite electrode.

Metal–organic framework derived Fe2O3@NiCo2O4 porous nanocages as anode materials for Li-ion batteries

A Fe2O3@NiO core/shell nanorod array on carbon cloth was prepared with the aid of hydrothermal synthesis combined with subsequent chemical bath deposition. The resultant array structure is composed of Fe2O3 nanorods as the core and interconnected ultrathin NiO nanoflakes as the shell. As an anode material for lithium-ion batteries, the heterostructured array electrode delivers a high discharge capacity of 1047.2 mA h g−1 after 50 cycles at 200 mA g−1, and 783.3 mA h g−1 at a high current density of 2000 mA g−1. The excellent electrochemical performance is attributed to the unique 3D core/shell nanorod array architecture and a rational combination of two electrochemical active materials. Our growth approach offers a simple and effective technique for the design and synthesis of a transition metal oxide hierarchical array that is promising for high-performance electrochemical energy storage.

A three-dimensional hierarchical Fe2O3@NiO core/shell nanorod array on carbon cloth: a new class of anode for high-performance lithium-ion batteries

Core-shell materials for advanced batteries

The development of portable and wearable electronics has promoted the increasing demand for high-performance power sources with high energy/power density, low cost, lightweight, as well as ultrathin and flexible features. Herein, a low-cost high-performance flexible asymmetric supercapacitor (ASC) with Co2AlO4@MnO2 nanosheets and Fe3O4 nanoflakes grown on nickel foam is designed and fabricated. The as-designed ASC device with an extended operating voltage window of 1.6 V achieves a specific capacitance of 99.1 F g−1 at a current density of 2 A g−1 with a maximum energy density of 35.3 W h kg−1 and very long-term cycling stability (92.4% capacitance after 5000 cycles).

Low-cost high-performance asymmetric supercapacitors based on Co2AlO4@MnO2 nanosheets and Fe3O4 nanoflakes

Modification and improvement of microalgae strains for strengthening CO2 fixation from coal-fired flue gas in power plants.

Phosphotungstic acid-modified zeolite imidazolate framework (ZIF-67) as an acid-base bifunctional heterogeneous catalyst for biodiesel production from microalgal lipids

Transcriptome sequencing and metabolic pathways of astaxanthin accumulated in Haematococcus pluvialis mutant under 15% CO2.

In this study, we synthesized C–Fe3O4–C core–shell nanotubes through a facile chemical vapor deposition (CVD) method using Fe2O3 nanotubes as the self-templates. The hydrothermal product α-Fe2O3 hematite exhibits a tubular structure with an inner diameter of 70–100 nm, a wall thickness of 10–20 nm, and a length of 300–800 nm. After the CVD reaction in C2H2, α-Fe2O3 could be transformed into C–Fe3O4–C with the tubular structure reserved. The tubular C–Fe3O4–C is constructed by an Fe3O4 nanotube core and 5 nm thick carbon shells on both inner and outer surfaces of the Fe3O4 nanotube. The C–Fe3O4–C nanotube anode exhibits a stable cycling with a capacity over 700 mA h g−1 retained after 120 cycles at 100 mA g−1. The improved electrochemical properties of C–Fe3O4–C nanotubes compared with bare α-Fe2O3 could be attributed to the introduction of the carbon shells, which not only supplya high conductive channel and buffer matrix, but also keep the structural stability of the Fe3O4 nanotube upon cycling.

Yanxia Zhu

Papers

Modification and improvement of microalgae strains for strengthening CO2 fixation from coal-fired flue gas in power plants.

Phosphotungstic acid-modified zeolite imidazolate framework (ZIF-67) as an acid-base bifunctional heterogeneous catalyst for biodiesel production from microalgal lipids

Transcriptome sequencing and metabolic pathways of astaxanthin accumulated in Haematococcus pluvialis mutant under 15% CO2.

Facile synthesis of C–Fe3O4–C core–shell nanotubes by a self-templating route and the application as a high-performance anode for Li-ion batteries

Simultaneous promotion of photosynthesis and astaxanthin accumulation during two stages of Haematococcus pluvialis with ammonium ferric citrate.