Iron oxide-based heterojunctions have garnered widespread interest in the field of photocatalysis due to their outstanding photoelectric properties.However,there remains a lack of an in-depth understanding of the rela...Iron oxide-based heterojunctions have garnered widespread interest in the field of photocatalysis due to their outstanding photoelectric properties.However,there remains a lack of an in-depth understanding of the relationship between the interfacial structure and electronic properties of these heterojunctions at the atomic scale.Access to such knowledge is critical for guiding the design and enhancing the efficiency of novel photocatalyst classes.Herein,a first-principles computational investigation focuses on the interfacial geometry,electronic structure and electron transfer mechanisms of MAPbI3/α-Fe_(2)O_(3),MAPbI3/γ-Fe_(2)O_(3) and MAPbI3/TiO_(2) heterojunctions.Compared to the classical MAPbI3/TiO_(2) system,the influence of iron coordination at the two octahedral iron sites ofα-Fe_(2)O_(3) and at both tetrahedral and octahedral iron sites ofγ-Fe_(2)O_(3) is investigated.This indicates that the stability of the interface on theγ-Fe_(2)O_(3)(111)surface is enhanced by the octahedrally coordinated iron,whereas the subsurface Fe_(o2) plays a pivotal role in stabilizing the interface with PbI on theα-Fe_(2)O_(3)-Fe_(o1) surface.Furthermore,a notable modulation by different iron coordinations of the valence band maximum charge distribution at theα-Fe_(2)O_(3)/PbI andγ-Fe_(2)O_(3)/PbI interfaces is observed,which is pivotal for the separation and transfer of photogenerated electrons and holes.Combined with the comprehensive analysis of the band structure,electrostatic potential and average plane charge density of the heterojunction,the MAPbI3/iron oxide heterojunction is consistent with the S-scheme heterojunction mechanism.Molecular adsorption simulations of CO_(2),O_(2) and H_(2)O show that theα-Fe_(2)O_(3)-Fe_(o1)/PbI interface stands out with the lowest adsorption energy,indicating its superior photocatalytic potential for CO_(2) reduction and dye degradation.These findings provide valuable insights into the design principles of photocatalytic materials,emphasizing the strategic manipulation of iron coordination to optimize iron-based heterojunction performance.展开更多
Although large amounts of engineered nanomaterials have been used for the arsenic removal, today there still remains several serious impediments to its further application, including consumption of expensive and pure ...Although large amounts of engineered nanomaterials have been used for the arsenic removal, today there still remains several serious impediments to its further application, including consumption of expensive and pure salts, and only application for the removal of inorganic arsenic. In this work, we developed an eco-economic and facile electrochemical method to synthesize iron porous coordination polymers （FePCPs） for the simultaneous removal of inorganic and organic arsenic from natural water.展开更多
Few spin-crossover materials with a 1D ladder-type structure have been reported.Previously,[Fe(Mebpt){Au(CN)_(2)}]·H_(2)O(MebptH=3-(5-methyl-2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole)was made and shown to display g...Few spin-crossover materials with a 1D ladder-type structure have been reported.Previously,[Fe(Mebpt){Au(CN)_(2)}]·H_(2)O(MebptH=3-(5-methyl-2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole)was made and shown to display gradual spin-crossover behaviour.In the current work,a new 1D iron(Ⅱ)ladder-type compound,[Fe(bpt){Au(CN)_(2)}](bptH=3-(2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole),was produced and showed enhanced spin-crossover behavior.It showed an abrupt spin transition above room temperature with a 3 K hysteresis(T_(1/2)↓=335 K and T_(1/2)↑=338 K).The origin of its enhanced spin-crossover could be ascribed to a greater influence of supramolecular interactions over the electronic substituent effect.展开更多
Atomically dispersed iron-nitrogen coordinated active sites on carbon(Fe-N-C)are considered to be absorbing materials that can be used as alternatives to Pt-based catalysts for the electrochemical oxygen reduction rea...Atomically dispersed iron-nitrogen coordinated active sites on carbon(Fe-N-C)are considered to be absorbing materials that can be used as alternatives to Pt-based catalysts for the electrochemical oxygen reduction reaction(ORR).However,Fe-N-C catalysts exhibit low metal loadings and unsatisfactory performance due to the imperfect electronic structure.Herein,atomically dispersed binary Fe-Fe dual-atom sites supported on hierarchically ordered porous N-doped carbon(denoted as FeNC-OAc)were synthesized via a universal carboxylate-assisted strategy.The iron ions could be stabilized by carboxylate,which promoted the formation of a Fe-Fe dual-atom catalyst with dense accessible active sites.Thanks to the high activity and accessibility of binary Fe-Fe active sites,the optimized 0.2FeNC-OAc catalyst exhibited superior oxygen reduction performance in alkaline solution,with a half-wave potential(E1/2)of 0.875 V,much higher than commercial 40 wt%Pt/C(0.853 V).Moreover,it displayed superior tolerance to methanol cross effects and electrochemical durability.This work affords a general method for the rapid preparation of electrocatalysts with bimetal active sites,which may promote the application of various atomic catalysts.展开更多
Defects in crystalline structures play a vital role in their properties,so their proper characterization is essential to understanding and improving the behaviour of the materials.In this work,their presence in Ca_(4)...Defects in crystalline structures play a vital role in their properties,so their proper characterization is essential to understanding and improving the behaviour of the materials.In this work,their presence in Ca_(4)Fe_(9)O_(17) has been analysed.Its structure exhibits three different iron coordination topologies and can be described as layers of corner-sharing FeO_(5) bipyramids stacked along the c axis together with layers of edge-sharing FeO_(6) octahedra,both being linked by FeO_(4) tetrahedra.The relative position of the FeO_(4) tetrahedra generates three possible stacking directions,which results in stacking faults when more than one is combined.Structural refinement using the Rietveld method in X-ray and neutron powder diffraction data was not possible due to significant mismatches between the observed and calculated integrated intensities for several peaks resulting from this atomic disorder.Selected area electron diffraction(SAED)and high-resolution scanning transmission electron microscopy(HR-STEM)images confirm the local defective nature of the material.The FAULTS software enabled a successful refinement of the structure considering a high concentration of planar defects,conferred by the existence of three possible stacking directions in the crystal structure,all of them confined in the basal plane.展开更多
基金supported by the Natural Science Foundation of Inner Mongolia of China[grant number 2021BS02018 and 2023QN02008].
文摘Iron oxide-based heterojunctions have garnered widespread interest in the field of photocatalysis due to their outstanding photoelectric properties.However,there remains a lack of an in-depth understanding of the relationship between the interfacial structure and electronic properties of these heterojunctions at the atomic scale.Access to such knowledge is critical for guiding the design and enhancing the efficiency of novel photocatalyst classes.Herein,a first-principles computational investigation focuses on the interfacial geometry,electronic structure and electron transfer mechanisms of MAPbI3/α-Fe_(2)O_(3),MAPbI3/γ-Fe_(2)O_(3) and MAPbI3/TiO_(2) heterojunctions.Compared to the classical MAPbI3/TiO_(2) system,the influence of iron coordination at the two octahedral iron sites ofα-Fe_(2)O_(3) and at both tetrahedral and octahedral iron sites ofγ-Fe_(2)O_(3) is investigated.This indicates that the stability of the interface on theγ-Fe_(2)O_(3)(111)surface is enhanced by the octahedrally coordinated iron,whereas the subsurface Fe_(o2) plays a pivotal role in stabilizing the interface with PbI on theα-Fe_(2)O_(3)-Fe_(o1) surface.Furthermore,a notable modulation by different iron coordinations of the valence band maximum charge distribution at theα-Fe_(2)O_(3)/PbI andγ-Fe_(2)O_(3)/PbI interfaces is observed,which is pivotal for the separation and transfer of photogenerated electrons and holes.Combined with the comprehensive analysis of the band structure,electrostatic potential and average plane charge density of the heterojunction,the MAPbI3/iron oxide heterojunction is consistent with the S-scheme heterojunction mechanism.Molecular adsorption simulations of CO_(2),O_(2) and H_(2)O show that theα-Fe_(2)O_(3)-Fe_(o1)/PbI interface stands out with the lowest adsorption energy,indicating its superior photocatalytic potential for CO_(2) reduction and dye degradation.These findings provide valuable insights into the design principles of photocatalytic materials,emphasizing the strategic manipulation of iron coordination to optimize iron-based heterojunction performance.
基金the National Natural Science Foundation of China (Nos. 21575092 and 21622508) for financial support
文摘Although large amounts of engineered nanomaterials have been used for the arsenic removal, today there still remains several serious impediments to its further application, including consumption of expensive and pure salts, and only application for the removal of inorganic arsenic. In this work, we developed an eco-economic and facile electrochemical method to synthesize iron porous coordination polymers （FePCPs） for the simultaneous removal of inorganic and organic arsenic from natural water.
基金supported by the NSFC(21373279,21501067,21601002 and 91422302)the Zhejiang Provincial Natural Science Foundation of China(Grant LQ15B010002)+1 种基金the Program for Science and Technology of Jiaxing(2015AY11011)the Start-up Grant from Jiaxing University(no.70514017).
文摘Few spin-crossover materials with a 1D ladder-type structure have been reported.Previously,[Fe(Mebpt){Au(CN)_(2)}]·H_(2)O(MebptH=3-(5-methyl-2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole)was made and shown to display gradual spin-crossover behaviour.In the current work,a new 1D iron(Ⅱ)ladder-type compound,[Fe(bpt){Au(CN)_(2)}](bptH=3-(2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole),was produced and showed enhanced spin-crossover behavior.It showed an abrupt spin transition above room temperature with a 3 K hysteresis(T_(1/2)↓=335 K and T_(1/2)↑=338 K).The origin of its enhanced spin-crossover could be ascribed to a greater influence of supramolecular interactions over the electronic substituent effect.
基金supported by the Natural Science Foundation of Guangxi Province(ZY21195038 and 2020GXNSFGA297004)the National Natural Science Foundation of China(22179026,52161035,and U20A20237)+2 种基金the Science and Technology Development Project of Guilin(20210102-4)the Guilin Lijiang Scholar Foundation,the Guangxi Bagui Scholar Foundation,the Key Foundation of Educational Commission of Anhui Province(2022AH050376 and KJ2021A0518)the Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technology(FC202208).
文摘Atomically dispersed iron-nitrogen coordinated active sites on carbon(Fe-N-C)are considered to be absorbing materials that can be used as alternatives to Pt-based catalysts for the electrochemical oxygen reduction reaction(ORR).However,Fe-N-C catalysts exhibit low metal loadings and unsatisfactory performance due to the imperfect electronic structure.Herein,atomically dispersed binary Fe-Fe dual-atom sites supported on hierarchically ordered porous N-doped carbon(denoted as FeNC-OAc)were synthesized via a universal carboxylate-assisted strategy.The iron ions could be stabilized by carboxylate,which promoted the formation of a Fe-Fe dual-atom catalyst with dense accessible active sites.Thanks to the high activity and accessibility of binary Fe-Fe active sites,the optimized 0.2FeNC-OAc catalyst exhibited superior oxygen reduction performance in alkaline solution,with a half-wave potential(E1/2)of 0.875 V,much higher than commercial 40 wt%Pt/C(0.853 V).Moreover,it displayed superior tolerance to methanol cross effects and electrochemical durability.This work affords a general method for the rapid preparation of electrocatalysts with bimetal active sites,which may promote the application of various atomic catalysts.
基金ALBA synchrotron(proposal 2019073634)ILL(EASY access system)+1 种基金Spain’s Agencia Estatal de Investigación Severo Ochoa Program for Centers of Excellence in R&D(CEX2019-000917-S)funding through grant PID2020-113805GB-I00.
文摘Defects in crystalline structures play a vital role in their properties,so their proper characterization is essential to understanding and improving the behaviour of the materials.In this work,their presence in Ca_(4)Fe_(9)O_(17) has been analysed.Its structure exhibits three different iron coordination topologies and can be described as layers of corner-sharing FeO_(5) bipyramids stacked along the c axis together with layers of edge-sharing FeO_(6) octahedra,both being linked by FeO_(4) tetrahedra.The relative position of the FeO_(4) tetrahedra generates three possible stacking directions,which results in stacking faults when more than one is combined.Structural refinement using the Rietveld method in X-ray and neutron powder diffraction data was not possible due to significant mismatches between the observed and calculated integrated intensities for several peaks resulting from this atomic disorder.Selected area electron diffraction(SAED)and high-resolution scanning transmission electron microscopy(HR-STEM)images confirm the local defective nature of the material.The FAULTS software enabled a successful refinement of the structure considering a high concentration of planar defects,conferred by the existence of three possible stacking directions in the crystal structure,all of them confined in the basal plane.
