Element doping is a simple and effective method to improve photocatalytic activity of g-C3N4. However, the doping model and mechanism of metal elements are still uncharacterized. In this study, we found that Fe(Ⅲ) ca...Element doping is a simple and effective method to improve photocatalytic activity of g-C3N4. However, the doping model and mechanism of metal elements are still uncharacterized. In this study, we found that Fe(Ⅲ) can be doped into g-C3N4 through the coordination between amidogen and Fe(Ⅲ). After activity tests, it was found that this coordination doping of Fe(Ⅲ) could enhance the Rh B oxidation and Cr(Ⅵ) reduction activities of g-C3N4 in interesting ways, but it is not helpful for the NO-removal performance of g-C3N4. Characterization and calculation results show that the coordination of Fe(Ⅲ) can not only improve the transfer of photogenerated electrons, but it also can passivate the carbon site of triazine rings, which is the active site of NO-removal. This study revealed some doping mechanisms and effect mechanisms of elemental metal in photocatalysis.展开更多
Using conversion electron spectroscopy(CEMS) and slow positron beam, the chemical state of 57Fe(100keV,3×1016 cm-2) implanted into ZrO2 containing 0.03 mole fraction Y2O3(ZY3) and its thermodynamic behavior duri...Using conversion electron spectroscopy(CEMS) and slow positron beam, the chemical state of 57Fe(100keV,3×1016 cm-2) implanted into ZrO2 containing 0.03 mole fraction Y2O3(ZY3) and its thermodynamic behavior during annealing process at 200 ￣ 500℃ are studied.For as-implanted sample, Fe chemical states of Fe0,Fe2+ and Fe3+ are observed,and assigned to the superparamagnetic metallic iron cluster,iron dimer(and trimer) and complex of the Fe3+ associated with canon vacancy (V) and oxygens respectively.After annealing at 400℃ the complexes of Fe3+-V are mostly dissolved,and the prior phase to α-Fe and α-Fe nano-crystalline cluster are present in the sample.Meanwhile the mixed conducting of oxygen-ions and electrons in the ZY3 sample containing Fe appears,it may correlate with the different iron charge states and their relative amounts,in particular with the α-Fe nano-granule.展开更多
Pillaring technologies have been considered as an effective way to improve lithium storage performance of Ti_(3)C_(2)T_(x)MXene.Nevertheless,the pillared hybrids suffer from sluggish Li^(+)diffusion kinetics and elect...Pillaring technologies have been considered as an effective way to improve lithium storage performance of Ti_(3)C_(2)T_(x)MXene.Nevertheless,the pillared hybrids suffer from sluggish Li^(+)diffusion kinetics and electronic transportation due to the compact multi-layered MXene structure,thus exhibiting inferior rate performance.Herein,the few-layered Ti_(3)O_(2)MXene(f-Ti_(3)C_(2)MXene)which is free from restacking can be prepared quickly based on the NH4^(+)ions method.Besides,Fe nanocomplex pillared few-layered Ti_(3)C_(2)T_(x)(FPTC)heterostructures are fabricated via the intercalation of Fe ions into the interlayer of f-Ti_(3)C_(2)MXene.The f-Ti_(3)C_(2)MXene which is immune to restacking can provide a highly conductive substrate for the rapid transport of Li+ions and electrons and possess adequate electrolyte accessible area.Moreover,f-Ti_(3)C_(2)MXene can efficiently relieve the aggregation,prevent the pulverization and buffer the large volume change of Fe nanocomplex during lithiation/delithiation process,leading to enhanced charge transfer kinetics and excellent structural stability of FPTC composites.Consequently,the FPTC hybrids exhibit a high capacity of 535 mAh·g^(-1)after 150 cycles at 0.5 A·g^(-1)and an enhanced rate performance with 310 mAh·g^(-1)after 850 cycles at 5 A·g^(-1).This strategy is facile,universal and can be extended tofabricate various few-layered MXene-derived hybrids with superior rate capability.展开更多
文摘Element doping is a simple and effective method to improve photocatalytic activity of g-C3N4. However, the doping model and mechanism of metal elements are still uncharacterized. In this study, we found that Fe(Ⅲ) can be doped into g-C3N4 through the coordination between amidogen and Fe(Ⅲ). After activity tests, it was found that this coordination doping of Fe(Ⅲ) could enhance the Rh B oxidation and Cr(Ⅵ) reduction activities of g-C3N4 in interesting ways, but it is not helpful for the NO-removal performance of g-C3N4. Characterization and calculation results show that the coordination of Fe(Ⅲ) can not only improve the transfer of photogenerated electrons, but it also can passivate the carbon site of triazine rings, which is the active site of NO-removal. This study revealed some doping mechanisms and effect mechanisms of elemental metal in photocatalysis.
文摘Using conversion electron spectroscopy(CEMS) and slow positron beam, the chemical state of 57Fe(100keV,3×1016 cm-2) implanted into ZrO2 containing 0.03 mole fraction Y2O3(ZY3) and its thermodynamic behavior during annealing process at 200 ￣ 500℃ are studied.For as-implanted sample, Fe chemical states of Fe0,Fe2+ and Fe3+ are observed,and assigned to the superparamagnetic metallic iron cluster,iron dimer(and trimer) and complex of the Fe3+ associated with canon vacancy (V) and oxygens respectively.After annealing at 400℃ the complexes of Fe3+-V are mostly dissolved,and the prior phase to α-Fe and α-Fe nano-crystalline cluster are present in the sample.Meanwhile the mixed conducting of oxygen-ions and electrons in the ZY3 sample containing Fe appears,it may correlate with the different iron charge states and their relative amounts,in particular with the α-Fe nano-granule.
基金the Tai hu Electric Corporation 0001 and the National Natural Science Foundation o f China(No.51901206).
文摘Pillaring technologies have been considered as an effective way to improve lithium storage performance of Ti_(3)C_(2)T_(x)MXene.Nevertheless,the pillared hybrids suffer from sluggish Li^(+)diffusion kinetics and electronic transportation due to the compact multi-layered MXene structure,thus exhibiting inferior rate performance.Herein,the few-layered Ti_(3)O_(2)MXene(f-Ti_(3)C_(2)MXene)which is free from restacking can be prepared quickly based on the NH4^(+)ions method.Besides,Fe nanocomplex pillared few-layered Ti_(3)C_(2)T_(x)(FPTC)heterostructures are fabricated via the intercalation of Fe ions into the interlayer of f-Ti_(3)C_(2)MXene.The f-Ti_(3)C_(2)MXene which is immune to restacking can provide a highly conductive substrate for the rapid transport of Li+ions and electrons and possess adequate electrolyte accessible area.Moreover,f-Ti_(3)C_(2)MXene can efficiently relieve the aggregation,prevent the pulverization and buffer the large volume change of Fe nanocomplex during lithiation/delithiation process,leading to enhanced charge transfer kinetics and excellent structural stability of FPTC composites.Consequently,the FPTC hybrids exhibit a high capacity of 535 mAh·g^(-1)after 150 cycles at 0.5 A·g^(-1)and an enhanced rate performance with 310 mAh·g^(-1)after 850 cycles at 5 A·g^(-1).This strategy is facile,universal and can be extended tofabricate various few-layered MXene-derived hybrids with superior rate capability.
