- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Can one introduce long range ferromagnetism by doping transition metal in wide band gap semiconducting ZnO?
摘要： In this report, we present a systematic study of magnetic behavior of transition metal (TM = Fe or Cu) doped ZnO and co-doped (Cu, Fe) ZnO nanoparticles. All the samples show antiferromagnetic (AFM) like inverse susceptibility at low temperatures. In all the samples AFM Curie-Weiss temperature TAF M increases with increase in TM ion concentration indicating enhanced antiferromagnetic correlation upon TM doping. We observe a crossover from antiferromagnetic correlation state to ferromagnetic correlation around temperature (T) 100 - 150K. We shall try to explain all the experimental observations by invoking the role of oxygen vacancies, valency of transition metal ions, formation and interaction between bound magnetic polaron (BMP) and their melting in ZnO matrix. Even though we observe ferromagnetic correlation around room temperature in all these samples from the inverse magnetic susceptibility data, but no true long range ferromagnetic transition was observed in magnetization down to lowest measured temperature of 5K. Our study indicates the di?culties in achieving long range ferromagnetism arising due to the formation of BMPs upon lowering the temperature where these BMPs get antiferromagnetically correlated due to superexchange interaction occurring in transition metal doped wide band gap semiconducting ZnO matrix.
关键词： Dilute magnetic semiconductor,Bound magnetic polaron,Antiferromagnetism,Transition metal doping,ZnO,Ferromagnetism
更新于2025-09-23 15:21:21
-
Enhanced Photocatalytic Activity of 2 <i>H</i> -MoSe <sub/>2</sub> by 3 <i>d</i> Transition Metal Doping
摘要： To develop MoSe2-based photocatalysts, increasing the catalytic activity of 2H-MoSe2 is essential. In this work, the electronic and photocatalytic properties of 3d transition metal (TM) doped (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) 2H-MoSe2 were investigated by first-principles calculations. The results indicate that Sc, Ti, V, Cr, Mn, Fe and Co atoms tend to substitute the Mo atoms under Se-rich condition, while Ni, Cu and Zn atoms prefer to occupy the interstitial positions. More importantly, Sc- and Ti-doped 2H-MoSe2 can enhance the photocatalytic activity by increasing the oxidizability of photogenerated holes, suppressing the recombination of photogenerated carriers and increasing the number of catalytic active sites.
关键词： photocatalytic activity,2H-MoSe2,3d transition metal doping,electronic properties,first-principles calculations
更新于2025-09-23 15:21:01
-
Energy Level Engineering in Transition-Metal Doped Spinel-Structured Nanosheets for Efficient Overall Water Splitting
摘要： Unraveling the role of transition-metal doping on affecting the native spinel-structured nanosheets’ water splitting remains a grand challenge. In this work, a series of spinel-structured nanosheets wrapped hollow nitrogen-doped carbon polyhedrons was constructed, and doped transition-metal domains were deliberately introduced on the surface. Theoretical investigations show that their energy level can be finely tuned via direct transition-metal doping engineering. As a prototype, Fe-doped NiCo2O4 nanosheets wrapped hollow nitrogen-doped carbon polyhedron (Fe-NiCo2O4@HNCP) exhibits outstanding bifunctional electrocatalytic performances with low overpotentials (η = 270 mV for OER, η = 84 mV for HER), low Tafel slopes (b = 42 mV dec-1 for OER, b = 47 mV dec-1 for HER), and high durability. The enhanced performance is attributed to the synergistic effects of energy level matching for electron transfer, and partial charge delocalization-induced rich active sites for reactant adsorption via thermodynamic and kinetic acceleration. This work may open a new pathway to design highly active and stable transtion-metal doped electrocatalysts by manipulated energy levels for efficient overall water splitting.
关键词： energy level engineering,water splitting,electrocatalysts,spinel-structured nanosheets,transition-metal doping
更新于2025-09-04 15:30:14