Electrochromic(EC)smart windows utilizing a reversible metal electrodeposition device(RMED)offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy.An EC device(ECD)is cons...Electrochromic(EC)smart windows utilizing a reversible metal electrodeposition device(RMED)offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy.An EC device(ECD)is constructed by reversible metal electrodeposition(RME)of Bi/Cu on WO_(3)·xH_(2)O film electrodeposited onto fluorine-doped tin oxide(FTO)transparent conductive glass.The electrolyte consists of CuCl_(2),BiCl_(3),KCl and HCl aqueous solution,supplying necessary components for both electrochemical and electrodeposition processes.The ECD shows ability to rapidly transition between colorless and black states,which achieves a large optical modulation of 77.0%at 570 nm.In the black state,the ECD exhibits a near-zero transmittance in the wavelength range of 400-1100 nm while maintaining 96.6%of its initial optical modulation after coloration/bleaching cycling of 60000 s,exhibiting good cyclic stability.This RMED has relatively high stability under open-circuit voltage and also possesses excellent heat insulation performance.The results offer a solution to overcome the poor cyclic stability of RMEDs and improve the optical modulation of ECDs.展开更多
Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Co...Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts.展开更多
以硝酸铝和尿素为原料,通过水热法成功合成富含五配位Al^(3+)的γ-Al_(2)O_(3)载体,采用XRD、SEM、STEM-HAADF、27Al MAS NMR、N_(2)吸附-脱附等手段表征了载体的物理化学性质,并对采用该载体制备的Pd/Al_(2)O_(3)催化剂进行了蒽醌加氢...以硝酸铝和尿素为原料,通过水热法成功合成富含五配位Al^(3+)的γ-Al_(2)O_(3)载体,采用XRD、SEM、STEM-HAADF、27Al MAS NMR、N_(2)吸附-脱附等手段表征了载体的物理化学性质,并对采用该载体制备的Pd/Al_(2)O_(3)催化剂进行了蒽醌加氢制H_(2)O_(2)的初步性能评价。表征结果显示,合成的载体中的五配位Al^(3+)相对含量可达40.88%(w),微观粒子呈棒状,棒的长度1~4μm,直径0.1~0.3μm,BET比表面积可达494 m^(2)/g;所制备的Pd/Al_(2)O_(3)催化剂中Pd纳米粒子分散良好,平均粒径为3.51 nm,且分布较窄。评价结果表明,该催化剂相对于参比剂具有较高的加氢活性。展开更多
A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material.The effects of Bi_(2)O_(3)in the PT...A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material.The effects of Bi_(2)O_(3)in the PTFE/Al/Bi_(2)O_(3)on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry,adiabatic oxygen bomb test and split Hopkinson pressure bar test.The microstructure observed through scanning electron microscope and Xray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi_(2)O_(3).The results indicate that the PTFE/Al/Bi_(2)O_(3)are capable of triggering the exothermic reaction of molten PTFE/Bi_(2)O_(3)and Al/Bi_(2)O_(3)over the PTFE/Al reactive materials,thereby promoting reactions.The excessive aluminum in the ternary system is beneficial for increasing energy release.The ignition of shock-induced chemical reactions in PTFE/Al/Bi_(2)O_(3)is closely related to the material fracture.The dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.展开更多
文摘Electrochromic(EC)smart windows utilizing a reversible metal electrodeposition device(RMED)offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy.An EC device(ECD)is constructed by reversible metal electrodeposition(RME)of Bi/Cu on WO_(3)·xH_(2)O film electrodeposited onto fluorine-doped tin oxide(FTO)transparent conductive glass.The electrolyte consists of CuCl_(2),BiCl_(3),KCl and HCl aqueous solution,supplying necessary components for both electrochemical and electrodeposition processes.The ECD shows ability to rapidly transition between colorless and black states,which achieves a large optical modulation of 77.0%at 570 nm.In the black state,the ECD exhibits a near-zero transmittance in the wavelength range of 400-1100 nm while maintaining 96.6%of its initial optical modulation after coloration/bleaching cycling of 60000 s,exhibiting good cyclic stability.This RMED has relatively high stability under open-circuit voltage and also possesses excellent heat insulation performance.The results offer a solution to overcome the poor cyclic stability of RMEDs and improve the optical modulation of ECDs.
基金supported by the National Natural Science Foundation of China(22302115,22072079)the Fundamental Research Program of Shanxi Province(202303021221056).
文摘Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts.
文摘以硝酸铝和尿素为原料,通过水热法成功合成富含五配位Al^(3+)的γ-Al_(2)O_(3)载体,采用XRD、SEM、STEM-HAADF、27Al MAS NMR、N_(2)吸附-脱附等手段表征了载体的物理化学性质,并对采用该载体制备的Pd/Al_(2)O_(3)催化剂进行了蒽醌加氢制H_(2)O_(2)的初步性能评价。表征结果显示,合成的载体中的五配位Al^(3+)相对含量可达40.88%(w),微观粒子呈棒状,棒的长度1~4μm,直径0.1~0.3μm,BET比表面积可达494 m^(2)/g;所制备的Pd/Al_(2)O_(3)催化剂中Pd纳米粒子分散良好,平均粒径为3.51 nm,且分布较窄。评价结果表明,该催化剂相对于参比剂具有较高的加氢活性。
基金the National Natural Science Foundation of China (Grant No.12002045)State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology (Grant No.QNKT22-09)。
文摘A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material.The effects of Bi_(2)O_(3)in the PTFE/Al/Bi_(2)O_(3)on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry,adiabatic oxygen bomb test and split Hopkinson pressure bar test.The microstructure observed through scanning electron microscope and Xray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi_(2)O_(3).The results indicate that the PTFE/Al/Bi_(2)O_(3)are capable of triggering the exothermic reaction of molten PTFE/Bi_(2)O_(3)and Al/Bi_(2)O_(3)over the PTFE/Al reactive materials,thereby promoting reactions.The excessive aluminum in the ternary system is beneficial for increasing energy release.The ignition of shock-induced chemical reactions in PTFE/Al/Bi_(2)O_(3)is closely related to the material fracture.The dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.
