Piezoelectric silicon carbide(SiC)has been quite attractive due to its superior chemical and physical properties as well as wide potential applications.However,the inherent brittleness and unsatisfactory piezoelectric...Piezoelectric silicon carbide(SiC)has been quite attractive due to its superior chemical and physical properties as well as wide potential applications.However,the inherent brittleness and unsatisfactory piezoelectric response of piezoelectric semiconductors remain the major obstacles to their diversified applications.Here,flexible multifunctional PVDF/6H-SiC composite fiber films are fabricated and utilized to assemble both piezoelectric nanogenerators(PENGs)and stress/temperature/light sensors.The open cir-cuit voltage(V_(oc))and the density of short circuit current(I_(sc))of the PENG based on the PVDF/5 wt%6H-SiC composite fiber films reach 28.94 V and 0.24μA cm^(-2),showing a significant improvement of 240%and 300%compared with that based on the pure PVDF films.The effect of 6H-SiC nanoparticles(NPs)on inducing interfacial polarization and stress concentration in composite fiber films is proved by first-principles calculation and finite element analysis.The stress/temperature/light sensors based on the composite fiber film also show high sensitivity to the corresponding stimuli.This study shows that the PVDF/6H-SiC composite fiber film is a promising candidate for assembling high-performance energy harvesters and diverse sensors.展开更多
Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level ...Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(Nos.51902020,51974021,and 52250091)+2 种基金the Fundamental Research Funds for the Central Universities of NO.FRF-TP-20-02C2This project is supported by the S tate Key Laboratory of Featured Metal Materials and Lifecycle Safety for Composite Structures,Guangxi University(Grant No.2021GXYSOF12)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-21-028).
文摘Piezoelectric silicon carbide(SiC)has been quite attractive due to its superior chemical and physical properties as well as wide potential applications.However,the inherent brittleness and unsatisfactory piezoelectric response of piezoelectric semiconductors remain the major obstacles to their diversified applications.Here,flexible multifunctional PVDF/6H-SiC composite fiber films are fabricated and utilized to assemble both piezoelectric nanogenerators(PENGs)and stress/temperature/light sensors.The open cir-cuit voltage(V_(oc))and the density of short circuit current(I_(sc))of the PENG based on the PVDF/5 wt%6H-SiC composite fiber films reach 28.94 V and 0.24μA cm^(-2),showing a significant improvement of 240%and 300%compared with that based on the pure PVDF films.The effect of 6H-SiC nanoparticles(NPs)on inducing interfacial polarization and stress concentration in composite fiber films is proved by first-principles calculation and finite element analysis.The stress/temperature/light sensors based on the composite fiber film also show high sensitivity to the corresponding stimuli.This study shows that the PVDF/6H-SiC composite fiber film is a promising candidate for assembling high-performance energy harvesters and diverse sensors.
基金supported by the National Natural Science Foundation of China(Grant No.52372283)China Postdoctoral Science Foundation(Grant No.2023M730826)+1 种基金Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23121)Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233425).
文摘Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.