The Nonreciprocal Errors in Fiber Optic Current Sensors

Nonreciprocal errors in fiber-optic current sensors, which are induced by environment fluctuations such as temperature and linear and angular vibrations, are specified. These errors in three current sensor configurations are evaluated and compared theoretically. The comparison indicates that the in-line sensor with strip waveguide modulator has the best resistance to the mentioned three environment fluctuations. Methods that may be used to suppress the nonreciprocal errors in different sensor configurations are suggested.     

Nanoparticles of Iron Nitride Encapsulated in Nitrogen-Doped Carbon Bulk Derived from Polyaniline/Fe2O3 Blends and Its Electrochemical Performance

Iron nitride nanoparticles encapsulated in nitrogen-doped carbon bulk is fabricated by a simple costep nitridation of Fe₂O₃ and carbonization of polyaniline. The microstructure and elemental composition of the materials are analyzed by transmission electron microscope, scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The pore size distribution and specific surface area of the materials are identified using nitrogen adsorption and desorption method. The results illustrate that iron nitride nanoparticles with 5–20 nm in size are uniformly dispersed in the carbon bulk. The presence of carbon bulk effectively prevents the agglomeration of iron nitride nanoparticles, making the electrochemical performance of iron nitride nanoparticles/carbon nitride composite nanomaterials superior to that of pure iron nitride nanomaterials. At a current density of 0.5 A g⁻¹, the specific capacitance (257.5 F g⁻¹) of the iron nitride nanoparticles/nitrogen-doped carbon bulk is much higher than that (119.5 F g⁻¹) of pure iron nitride.     

Polyoxometalate-Incorporated Host-Guest Framework Derived Layered Double Hydroxide Composites for High-Performance Hybrid Supercapacitor†

Metal organic frameworks have been employed as high-performance layered double hydroxide (LDH) composite supercapacitor electrode materials but have shown unsatisfactory redox ability and stability. Herein, a host-guest CuMo-based polyoxometalate-based metal organic framework (POMOF) with copious electrochemically active sites and strong electrochemical redox activities has been effectively coupled with POM-incorporated CoNi-LDH to develop a nanocomposite (NENU-5@CoNi-LDH) by a simple solvothermal method. The designed electrode shows a high specific capacity of 333.61 mAh·g^–1 at 1 A·g^–1. In addition, the novel hybrid symmetric supercapacitor NENU-5@CoNi-LDH/active carbon (AC) demonstrated a high energy density of 80.8 Wh·kg^–1 at a power density of 750.7 W·kg^–1. Interestingly, the nanocomposite of NENU-5@CoNi-LDH exhibits an outstanding capacitance retention of 79% after 5000 charge-discharge cycles at 10 A·g^–1. This work provides a new strategy and will be the backbone for future energy storage research.