Photocatalytic O_(2)activation to generate reactive oxygen species is crucially important for purifying organic pollutants,yet remains a challenge due to poor adsorption of O_(2)and low efficiency of electron transfer...Photocatalytic O_(2)activation to generate reactive oxygen species is crucially important for purifying organic pollutants,yet remains a challenge due to poor adsorption of O_(2)and low efficiency of electron transfer.Herein,we demonstrate that ultrafine MoO_(x)clusters anchored on graphitic carbon nitride(g-C_(3)N_(4))with dual nitrogen/oxygen defects promote the photocatalytic activation of O_(2)to generate·O_(2)−for the degradation of tetracycline hydrochloride(TCH).A range of characterization techniques and density functional theory(DFT)calculations reveal that the introduction of the nitrogen/oxygen dual defects and MoO_(x)clusters enhances the O_(2)adsorption energy from−2.77 to−2.94 eV.We find that MoO_(x)clusters with oxygen vacancies(Ov)and surface Ov-mediated Moδ+(3≥δ≥2)possess unpaired localized electrons,which act as electron capture centers to transfer electrons to the MoO_(x)clusters.These electrons can then transfer to the surface adsorbed O_(2),thus promoting the photocatalytic conversion of O_(2)to·O_(2)−and,simultaneously,realizing the efficient separation of photogenerated electron–hole pairs.Our fully-optimized MoO_(x)/g-C_(3)N_(4)catalyst with dual nitrogen/oxygen defects manifests outstanding photoactivities,achieving 79%degradation efficiency toward TCH within 120 min under visible light irradiation,representing nearly 7 times higher activity than pristine g-C_(3)N_(4).Finally,based on the results of liquid chromatograph mass spectrometry and DFT calculations,the possible photocatalytic degradation pathways of TCH were proposed.展开更多
Metal phosphides have shown great application potential as anode for sodium-ion batteries(NIBs)owing to high theoretical capacity,suitable operation voltage and abundant resource.Unfortunately,the application of NiP_(...Metal phosphides have shown great application potential as anode for sodium-ion batteries(NIBs)owing to high theoretical capacity,suitable operation voltage and abundant resource.Unfortunately,the application of NiP_(2) anode is severely impeded by low practical capacity and fast capacity decay due to the huge volume variation and low reactivity of internal phosphorus(P)component towards Na^(+).Herein,electronic structure modulation of NiP_(2) via heteroatoms doping and introducing vacancies defects to enhance Na+adsorption sites and diffusion kinetics is successfully attempted.The as-synthesized three-dimensional(3D)bicontinuous carbon matrix decorated with well-dispersed fluorine(F)-doped NiP_(2) nanoparticles(F-NiP_(2)@carbon nanosheets)delivers a high reversible capacity(585 mAh·g^(−1) at 0.1 A·g^(−1))and excellent long cycling stability(244 mAh·g^(−1) over 1,000 cycles at 2 A·g^(−1))when tested as anode in NIBs.Density functional theory(DFT)calculations reveal that F doping in NiP_(2) induces the formation of P vacancies with increased Na+adsorption energy and accelerates the alloying of internal P component.The F-NiP_(2)@carbon nanosheets//Na_(3)V_(2)(PO_(4))_(3) full cell is evaluated showing stable long cycling life.The heteroatoms doping-induced dual defects strategy opens up a new way of metal phosphides for sodium storage.展开更多
We study the surface defect gap solitons in an interface between a defect of one-dimensional dual-frequency lattices and the uniform media. Some unique properties are revealed that such lattices can broaden the region...We study the surface defect gap solitons in an interface between a defect of one-dimensional dual-frequency lattices and the uniform media. Some unique properties are revealed that such lattices can broaden the region of semi-finite gap, and the semi-finite gap exists not only in the positive and zero defects but also in the negative defect; unlike in the regular lattices, the semi-finite gap exists in the positive and zero defects but does not exist in the negative defect. In particular, stable solitons exist almost in the whole semi-finite gap for the positive and zero defects. These properties are different from other lattices with defects. In addition, it is found that the existence of surface dual-frequency lattice solitons does not need a threshold power.展开更多
基金supported by the National Natural Science Foundation of China(No.21972010)the National Key Research and Development Program of China(No.2022YFC2105900).
文摘Photocatalytic O_(2)activation to generate reactive oxygen species is crucially important for purifying organic pollutants,yet remains a challenge due to poor adsorption of O_(2)and low efficiency of electron transfer.Herein,we demonstrate that ultrafine MoO_(x)clusters anchored on graphitic carbon nitride(g-C_(3)N_(4))with dual nitrogen/oxygen defects promote the photocatalytic activation of O_(2)to generate·O_(2)−for the degradation of tetracycline hydrochloride(TCH).A range of characterization techniques and density functional theory(DFT)calculations reveal that the introduction of the nitrogen/oxygen dual defects and MoO_(x)clusters enhances the O_(2)adsorption energy from−2.77 to−2.94 eV.We find that MoO_(x)clusters with oxygen vacancies(Ov)and surface Ov-mediated Moδ+(3≥δ≥2)possess unpaired localized electrons,which act as electron capture centers to transfer electrons to the MoO_(x)clusters.These electrons can then transfer to the surface adsorbed O_(2),thus promoting the photocatalytic conversion of O_(2)to·O_(2)−and,simultaneously,realizing the efficient separation of photogenerated electron–hole pairs.Our fully-optimized MoO_(x)/g-C_(3)N_(4)catalyst with dual nitrogen/oxygen defects manifests outstanding photoactivities,achieving 79%degradation efficiency toward TCH within 120 min under visible light irradiation,representing nearly 7 times higher activity than pristine g-C_(3)N_(4).Finally,based on the results of liquid chromatograph mass spectrometry and DFT calculations,the possible photocatalytic degradation pathways of TCH were proposed.
基金the National Natural Science Foundation of China(Nos.22005201 and 22005292)the Natural Science Foundation of Guangdong(No.2020A1515010840)Shenzhen Government’s Plan of Science and Technology(Nos.JCYJ20200109105803806 and RCYX20200714114535052).
文摘Metal phosphides have shown great application potential as anode for sodium-ion batteries(NIBs)owing to high theoretical capacity,suitable operation voltage and abundant resource.Unfortunately,the application of NiP_(2) anode is severely impeded by low practical capacity and fast capacity decay due to the huge volume variation and low reactivity of internal phosphorus(P)component towards Na^(+).Herein,electronic structure modulation of NiP_(2) via heteroatoms doping and introducing vacancies defects to enhance Na+adsorption sites and diffusion kinetics is successfully attempted.The as-synthesized three-dimensional(3D)bicontinuous carbon matrix decorated with well-dispersed fluorine(F)-doped NiP_(2) nanoparticles(F-NiP_(2)@carbon nanosheets)delivers a high reversible capacity(585 mAh·g^(−1) at 0.1 A·g^(−1))and excellent long cycling stability(244 mAh·g^(−1) over 1,000 cycles at 2 A·g^(−1))when tested as anode in NIBs.Density functional theory(DFT)calculations reveal that F doping in NiP_(2) induces the formation of P vacancies with increased Na+adsorption energy and accelerates the alloying of internal P component.The F-NiP_(2)@carbon nanosheets//Na_(3)V_(2)(PO_(4))_(3) full cell is evaluated showing stable long cycling life.The heteroatoms doping-induced dual defects strategy opens up a new way of metal phosphides for sodium storage.
基金Project supported by the National Natural Science Foundation of China (Grant No 10774031)Natural Science Foundation of Guangdong Province of China (Grant No 07001790)
文摘We study the surface defect gap solitons in an interface between a defect of one-dimensional dual-frequency lattices and the uniform media. Some unique properties are revealed that such lattices can broaden the region of semi-finite gap, and the semi-finite gap exists not only in the positive and zero defects but also in the negative defect; unlike in the regular lattices, the semi-finite gap exists in the positive and zero defects but does not exist in the negative defect. In particular, stable solitons exist almost in the whole semi-finite gap for the positive and zero defects. These properties are different from other lattices with defects. In addition, it is found that the existence of surface dual-frequency lattice solitons does not need a threshold power.
