Xue-Zhi Song

Concave ZnFe2O4 Hollow Octahedral Nanocages Derived from Fe-Doped MOF-5 for High-Performance Acetone Sensing at Low-Energy Consumption

Herein, through a morphology-inherited annealing treatment of a hollow Fe-doped MOF-5 octahedron as the self-sacrificing template, we report the synthesis of concave ZnFe2O4 hollow octahedral nanocages as sensing materials, which exhibited high performance, including unprecedented excellent sensitivity, good selectivity, and cyclic stability at ultralow working temperature (120 °C).

Carbon coated nickel–cobalt bimetallic sulfides hollow dodecahedrons for a supercapacitor with enhanced electrochemical performance

Due to the high power density and long cycle life, supercapacitors have been regarded as one of the most promising energy storage devices. In the present work, by the sulfuration of Ni–Co coexisting well-defined ZIF-67 dodecahedrons, hollow bimetal sulfides composed of Ni3xCo3−3xS4 nanobuilding blocks were successfully achieved. Subsequently, after hydrothermal treatment by glucose, the bimetallic sulfides were coated by carbon, leading to the formation of Ni3xCo3−3xS4@carbon (NCSC-x, x = 0.2) hollow dodecahedrons. When evaluated as a supercapacitor electrode, the specific capacitance of NCSC-0.2 can reach 696 F g−1 and 480 F g−1 in KOH (6 M) at the current densities of 1 A g−1 and 20 A g−1, respectively, which are much higher than those (305 F g−1 and 116.7 F g−1) of bare Ni3xCo3−3xS4 (NCS-0.2, x = 0.2) under the same measurement conditions. Furthermore, the NCSC-0.2 electrode presents a better cyclic stability, with 73% capacitance retention after 2000 charge and discharge cycles at a current density of 10 A g−1. The synergistic effect of the bimetallic components, hollow structures and carbon coating accounts for the enhanced electrochemical performance, paving the way towards other advanced supercapacitors for future high-performance energy storage by using structurally designed and suitably functionalized MOFs based nano-precursors.

Hollow NiFe2O4 microspindles derived from Ni/Fe bimetallic MOFs for highly sensitive acetone sensing at low operating temperatures

Hollow semiconductor oxide micro-/nanomaterials can provide significant advantages for gas sensing by facilitating the diffusion of target gases and the surface reaction. In this study, we report the synthesis of hollow NiFe2O4 microspindles through an as-developed metal–organic framework (MOF) route, which involves two steps: the preparation of Ni/Fe bimetallic MOF solid microspindle precursors and their subsequent transformation to the final materials via an annealing treatment in the air. The hollow NiFe2O4 microspindles were demonstrated to be composed of primary nano-building particles and abundant deep pores in the hollowed-out shells. Furthermore, in synergy with the large specific surface area, hollow interior, and abundant surface oxygen species, as expected, the gas sensor based on the hollow NiFe2O4 microspindles delivered a high sensitivity of 52.8 towards 200 ppm acetone vapor as well as good selectivity and cyclic stability at a low working temperature (120 °C). Finally, the sensing mechanism for the gas sensing behavior was also proposed. The high-performance sensing behavior towards acetone suggests that the as-fabricated sensor can be a promising candidate for environmental monitoring; thus, this study paves the way towards the efficient fabrication of advanced gas sensors on the basis of metal oxides derived from appropriate MOF precursors in the future.

Hollow NiFe2O4 hexagonal biyramids for high-performance n-propanol sensing at low temperature

Through annealing treatment of Ni/Fe-fumaric acid bimetallic MOF precursors, hollow NiFe2O4 hexagonal biyramids were synthesized. When evaluated as sensing materials, the n-type semiconductive sensor exhibited high performances including a high response value of 32.19 after exposure to 200 ppm n-propanol and good selectivity and cyclic stability when operating at a low temperature (120 °C).