The ion-exchanger LiMg0.5Mn1.5O4 of spinel type was prepared by the common precipitation/heated crystallization method, and was acid modified. Its properties of ion-exchange for alkali ions such as saturation capacity...The ion-exchanger LiMg0.5Mn1.5O4 of spinel type was prepared by the common precipitation/heated crystallization method, and was acid modified. Its properties of ion-exchange for alkali ions such as saturation capacity of exchange, distribution coefficient and the pH titration curve have been determined. LiMg0.5Mn1.5O4 was characterized by X-ray diffraction. These results show that this inorganic ion-exchanger has better remembering and selectivity of ion exchange, and higher capacity of exchange for Li+, the capacity of exchange reaches 32.39 mg·g-1 for Li+.展开更多
Ferrites are the most widely used microwave absorbing materials to deal with the threat of electromagnetic(EM)pollution.However,the lack of sufficient dielectric loss capacity is the main challenge that limits their a...Ferrites are the most widely used microwave absorbing materials to deal with the threat of electromagnetic(EM)pollution.However,the lack of sufficient dielectric loss capacity is the main challenge that limits their applications.To cope with this challenge,three high-entropy(HE)spineltype ferrite ceramics including(Mg_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2))Fe_(2)O_(4),(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2))Fe_(2)O_(4),and(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Zn_(0.2))Fe_(2)O_(4)were designed and successfully prepared through solid state synthesis.The results show that all three HE MFe_(2)O_(4) samples exhibit synergetic dielectric loss and magnetic loss.The good magnetic loss ability is due to the presence of magnetic components;while the enhanced dielectric properties are attributed to nano-domain,hopping mechanism of resonance effect and HE effect.Among three HE spinels,(Mg_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2))Fe_(2)O_(4)shows the best EM wave absorption performance,e.g.,its minimum reflection loss(RL_(min))reaches-35.10 dB at 6.78 GHz with a thickness of 3.5 mm,and the optimized effective absorption bandwidth(EAB)is 7.48 GHz from 8.48 to 15.96 GHz at the thickness of 2.4 mm.Due to the easy preparation and strong EM dissipation ability,HE MFe_(2)O_(4) are promising as a new type of EM absorption materials.展开更多
Spinel-type cathodes are considered an optimal substitute for conventional layered oxide cathodes owing to their use of inexpensive and earth-abundant manganese as the redox-active element.Moreover,the introduction of...Spinel-type cathodes are considered an optimal substitute for conventional layered oxide cathodes owing to their use of inexpensive and earth-abundant manganese as the redox-active element.Moreover,the introduction of cation disorder can effectively suppress the detrimental two-phase reaction to realize high capacities in a wide voltage range.However,the continuous capacity decay during cycles has hindered the widespread application of these cathode materials.Inorganic fluorides exhibit excellent electrochemical stability at high voltage;therefore,in this study,the direct F2 gas reaction with a partially disordered spinel cathode(Li_(1.6)Mn_(1.6)O_(3.7)F_(0.3,)LMOF1.6)was initially applied to investigate the impacts of fluorination on the surface structure and electrochemical performances.The inorganic fluorinated layer,mainly containing LiF,was distributed uniformly on the surface of LMOF1.6nanoparticles after fluorination for an appropriate time without the turbulence caused by the valency of manganese cation,which improved the capacity retention and rate capability by the suppression of structural damage,parasitic reaction,and cation dissolution.The LMOF1.6cathode fluorinated for 0.5 h exhibited a capacity of283.6 mAh·g^(-1)at 50 mA·g^(-1)and an enhanced capacity retention of 29.6%after 50 cycles in the voltage range of1.5-4.8 V,as compared to the pristine LMOF1.6 with only27.9%capacity retention.展开更多
Designing high-efficiency photocatalysts responsive to visible light is important for the degradation of antibiotics in water.Heterojunction engineering is undoubtedly an effective strategy to improve the photocatalyt...Designing high-efficiency photocatalysts responsive to visible light is important for the degradation of antibiotics in water.Heterojunction engineering is undoubtedly an effective strategy to improve the photocatalytic performance.In this work,spinel-type metal oxides(NiAl_(2)O_(4),NAO)are synthesized by a simple sol-gel and calcination process.After compounding graphitic carbon nitride(g-C_(3)N_(4)),NAO/g-C_(3)N_(4) heterojunction is obtained,which then is used as the photocatalyst for tetracycline hydrochloride(TC).The effects of photocatalyst dosage,the initial concentration of TC,and solution pH on photodegradation performance are systematically studied.The removal rate of TC on NAO/g-C_(3)N_(4) reach up to∼90%after visible light irradiation for 2 hr and the degradation rate constant is∼7 times,and∼32 times higher than that of pure NAO and g-C_(3)N_(4).The significantly improved photocatalytic activity can be attributed to the synergistic effect between well matched energy levels in NAO/g-C_(3)N_(4) heterojunctions,improvement of interfacial charge transfer,and enhancement of visible light absorption.This study provides a way for the synthesis of efficient photocatalysts and an economic strategy for removing antibiotics contamination in water.展开更多
文摘The ion-exchanger LiMg0.5Mn1.5O4 of spinel type was prepared by the common precipitation/heated crystallization method, and was acid modified. Its properties of ion-exchange for alkali ions such as saturation capacity of exchange, distribution coefficient and the pH titration curve have been determined. LiMg0.5Mn1.5O4 was characterized by X-ray diffraction. These results show that this inorganic ion-exchanger has better remembering and selectivity of ion exchange, and higher capacity of exchange for Li+, the capacity of exchange reaches 32.39 mg·g-1 for Li+.
基金supported by the National Natural Science Foundation of China(Grant Nos.51802289 and 51972089)Financial supports of the Science Foundation for the Excellent Youth Scholars of Henan Province(Grant No.212300410089)the Support Program for Scientific and Technological Innovation Talents of Higher Education in Henan Province(Grant No.21HASTIT004)。
文摘Ferrites are the most widely used microwave absorbing materials to deal with the threat of electromagnetic(EM)pollution.However,the lack of sufficient dielectric loss capacity is the main challenge that limits their applications.To cope with this challenge,three high-entropy(HE)spineltype ferrite ceramics including(Mg_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2))Fe_(2)O_(4),(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2))Fe_(2)O_(4),and(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Zn_(0.2))Fe_(2)O_(4)were designed and successfully prepared through solid state synthesis.The results show that all three HE MFe_(2)O_(4) samples exhibit synergetic dielectric loss and magnetic loss.The good magnetic loss ability is due to the presence of magnetic components;while the enhanced dielectric properties are attributed to nano-domain,hopping mechanism of resonance effect and HE effect.Among three HE spinels,(Mg_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2))Fe_(2)O_(4)shows the best EM wave absorption performance,e.g.,its minimum reflection loss(RL_(min))reaches-35.10 dB at 6.78 GHz with a thickness of 3.5 mm,and the optimized effective absorption bandwidth(EAB)is 7.48 GHz from 8.48 to 15.96 GHz at the thickness of 2.4 mm.Due to the easy preparation and strong EM dissipation ability,HE MFe_(2)O_(4) are promising as a new type of EM absorption materials.
基金financially supported by the National Key R and D Program of China(No.2022YFB3805702)State Key Program of the National Natural Science Foundation of China(No.52130303)+1 种基金National Natural Science Foundation of China(Nos.51973152,51973119,5210309352173078)。
文摘Spinel-type cathodes are considered an optimal substitute for conventional layered oxide cathodes owing to their use of inexpensive and earth-abundant manganese as the redox-active element.Moreover,the introduction of cation disorder can effectively suppress the detrimental two-phase reaction to realize high capacities in a wide voltage range.However,the continuous capacity decay during cycles has hindered the widespread application of these cathode materials.Inorganic fluorides exhibit excellent electrochemical stability at high voltage;therefore,in this study,the direct F2 gas reaction with a partially disordered spinel cathode(Li_(1.6)Mn_(1.6)O_(3.7)F_(0.3,)LMOF1.6)was initially applied to investigate the impacts of fluorination on the surface structure and electrochemical performances.The inorganic fluorinated layer,mainly containing LiF,was distributed uniformly on the surface of LMOF1.6nanoparticles after fluorination for an appropriate time without the turbulence caused by the valency of manganese cation,which improved the capacity retention and rate capability by the suppression of structural damage,parasitic reaction,and cation dissolution.The LMOF1.6cathode fluorinated for 0.5 h exhibited a capacity of283.6 mAh·g^(-1)at 50 mA·g^(-1)and an enhanced capacity retention of 29.6%after 50 cycles in the voltage range of1.5-4.8 V,as compared to the pristine LMOF1.6 with only27.9%capacity retention.
基金supported by the National Natural Science Foundation of China(No.21908242).
文摘Designing high-efficiency photocatalysts responsive to visible light is important for the degradation of antibiotics in water.Heterojunction engineering is undoubtedly an effective strategy to improve the photocatalytic performance.In this work,spinel-type metal oxides(NiAl_(2)O_(4),NAO)are synthesized by a simple sol-gel and calcination process.After compounding graphitic carbon nitride(g-C_(3)N_(4)),NAO/g-C_(3)N_(4) heterojunction is obtained,which then is used as the photocatalyst for tetracycline hydrochloride(TC).The effects of photocatalyst dosage,the initial concentration of TC,and solution pH on photodegradation performance are systematically studied.The removal rate of TC on NAO/g-C_(3)N_(4) reach up to∼90%after visible light irradiation for 2 hr and the degradation rate constant is∼7 times,and∼32 times higher than that of pure NAO and g-C_(3)N_(4).The significantly improved photocatalytic activity can be attributed to the synergistic effect between well matched energy levels in NAO/g-C_(3)N_(4) heterojunctions,improvement of interfacial charge transfer,and enhancement of visible light absorption.This study provides a way for the synthesis of efficient photocatalysts and an economic strategy for removing antibiotics contamination in water.
