Wen Xin,Lin Chensheng,Luo Min,Fan Huixin,Chen Kaichuang,Ye Ning
[PO 4 ] 3− possesses small microscopic second-order susceptibility and polarizability anisotropy, which inherently result in weak second-harmonic generation (SHG) and small birefringence. Herein, a new noncentrosymmetric phosphate, [C(NH 2 ) 3 ] 3 PO 4 ·2H 2 O, was successfully designed and synthesized by a solution evaporation method. [C(NH 2 ) 3 ] 3 PO 4 ·2H 2 O without metal ions is composed of planar conjugated guanidine cations and PO 4 tetrahedrons, which are connected by hydrogen bonds, forming a three-dimensional network. Physical property measurements indicate that the title compound displays an SHG response of 1.5 × KH 2 PO 4 (KDP) and a larger birefringence (0.055@546.1 nm) compared with most reported ultraviolet nonlinear optical phosphates. Furthermore, first-principles calculations reveal that the π-conjugated planar [C(NH 2 ) 3 ] + cations and [PO 4 ] 3− groups are responsible for its excellent linear and NLO properties.
Transition-metal compounds have received extensive attention from researchers due to their high reversible capacity and suitable voltage platform as potassium-ion battery anodes. However, these materials commonly feature a poor conductivity and a large volume expansion, thus leading to underdeveloped rate capability and cyclic stability. Herein, we successfully encapsulated ultrafine CoP and CoSb nanoparticles into rich N-doped carbon nanofibers (NCFs) via electrospinning, carbonization, and phosphorization (antimonization). The N-doped carbon fiber prevents the aggregation of nanoparticles, buffers the volume expansion of CoP and CoSb during charging and discharging, and improves the conductivity of the composite material. As a result, the CoP/NCF anode exhibits excellent potassium-ion storage performance, including an outstanding reversible capacity of 335 mA h g −1 , a decent capacity retention of 79.3% after 1000 cycles at 1 A g −1 and a superior rate capability of 148 mA h g −1 at 5 A g −1 , superior to most of the reported transition-metalbased potassium-ion battery anode materials.
危险品化学品经营许可证（带存储）