Heterostructured BiOI@La（OH）3 nanorod photocatalysts were prepared by a facile chemical impregnation method.The enhanced visible light absorption and charge carrier separation can be simultaneously realized after th...Heterostructured BiOI@La（OH）3 nanorod photocatalysts were prepared by a facile chemical impregnation method.The enhanced visible light absorption and charge carrier separation can be simultaneously realized after the introduction of BiOI particles into La（OH）3 nanorods.The BiOI@La（OH）3 composites were applied for visible light photocatalytic oxidization of NO in air and exhibited an enhanced activity compared with BiOI and pure La（OH）3 nanorods.The results show that the energy levels between the La（OH）3 and BiOI phases matched well with each other,thus forming a heterojunctioned BiOI@La（OH）3 structure.This band structure matching could promote the separation and transfer of photoinduced electron-hole pairs at the interface,resulting in enhanced photocatalytic performance under visible light irradiation.The photocatalytic performance of BiOI@La（OH）3 is shown to be dependent on the mass ratio of BiOI to La（OH）3.The highest photocatalytic performance can be achieved when the mass ratio of BiOI to La（OH）3 is controlled at 1.5.A further increase of the mass ratio of BiOI weakened the redox abilities of the photogenerated charge carriers.A new photocatalytic mechanism for BiOI@La（OH）3 heterostructures is proposed,which is directly related to the efficient separation of photogenerated charge carriers by the heterojunction.Importantly,the as-prepared BiOI@La（OH）3 heterostructures exhibited a high photochemical stability after multiple reaction runs.Our findings demonstrate that BiOI is an effective component for the formation of a heterostructure with the properties of a wide bandgap semiconductor,which is of great importance for extending the light absorption and photocatalytic activity of wide bandgap semiconductors into visible light region.展开更多
We report a one‐pot surfactant‐free wet‐chemical reduction approach to the synthesis of palladium/titanium nitride(Pd/TiN)and Pd/carbon(Pd/C)composites,in which^5 nm Pd NPs were uniformly dispersed on TiN or C.In t...We report a one‐pot surfactant‐free wet‐chemical reduction approach to the synthesis of palladium/titanium nitride(Pd/TiN)and Pd/carbon(Pd/C)composites,in which^5 nm Pd NPs were uniformly dispersed on TiN or C.In terms of catalytic performance,Pd/TiN showed enhanced efficiency and stability compared with those of Pd/C and bare TiN in the electrocatalytic hydrodechlorination(EHDC)reaction of 2,4‐dichlorophenol(2,4‐DCP)in aqueous solution.The superior performance of Pd/TiN arises from the promotion effect of TiN.Strong metal‐support interactions modified the electronic structure of Pd,which optimized generation of H*ads and 2,4‐DCP adsorption/activation.The cathode potential plays a vital role in controlling the EHDC efficiency and the product distribution.A working potential of?0.80 V was shown to be optimal for achieving the highest EHDC efficiency and maximizing conversion of 2,4‐DCP to phenol(P).Our studies of the reaction pathway show that EHDC of 2,4‐DCP on Pd/TiN proceeded by 2,4‐DCP→p‐chlorophenol(p‐CP),o‐chlorophenol(o‐CP)→P;however,Pd/TiN presented little selectivity for cleavage of p‐C‐Cl vs o‐C‐Cl.This work presents a new approach to enhancing Pd performance towards EHDC through the effects of a support.The strategy demonstrated here could also be extended to design highly efficient catalysts for other hydrogenation reactions.展开更多
Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2w...Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.展开更多
Dynamic defects on halide perovskite materials,caused by ion dissociation and migration under light illumination,typically result in undesirable energy dissipation and limited energy conversion efficiency.However,in t...Dynamic defects on halide perovskite materials,caused by ion dissociation and migration under light illumination,typically result in undesirable energy dissipation and limited energy conversion efficiency.However,in this work,we demonstrated that dynamic halogen defects generated by the same process in bismuth oxyhalide(Bi_(5)O_(7)Cl)materials can act as active sites to promote charge separation and photocatalytic efficiency.Mechanistic studies and density functional theory calculations revealed that dynamic Cl defects affected the electronic structure of Bi_(5)O_(7)Cl and photocatalytic CO_(2)reduction process.As active sites,these defects promoted charge transfer,leading to the activation of adsorbed CO_(2)molecules and reduction of the energy barrier of the rate-determining step.Thus,CO_(2)was spontaneously converted into COOH−intermediate and finally reduced to CO with a high efficiency of 108.60μmol g^(−1) and selectivity of 100%after 4-h of CO_(2)photoreduction.This work is highly instructive and valuable to the exploration of dynamic defects on halide-containing materials applied in solar energy conversion.展开更多
The accumulation of intermediates or final products on TiO2 during photocatalytic volatile organic compounds(VOCs)degradation is typically neglected,despite the fact that it could result in the block of active sites a...The accumulation of intermediates or final products on TiO2 during photocatalytic volatile organic compounds(VOCs)degradation is typically neglected,despite the fact that it could result in the block of active sites and the deactivation of photocatalysts.Inspired from the natural formation of stalactite(CaCO3+H2O+CO2←→Ca(HCO3)2),we fabricated CaCO3 loading TiO2 composites(CCT21)to realize the spontaneously transfer of accumulated final products(CO2 and H2O).Efficient and durable performance for gaseous toluene removal has been demonstrated and the cost of photocatalyst is greatly reduced by the comparison of specific activity.The introduction of CaCO3 induces the interaction between TiO2 and CaCO3 to stimulate abundant activated electrons for the improvement on the adsorption and activation of reactants and the transformation of photogenerated carriers,and most importantly,facilitates the transfer of final products to release active sites and thus suppress the deactivation of TiO2.Furthermore,we develop a facile method to immobilize CCT21 powder on flexible support,which greatly reduces the loss of photocatalysts and correspondingly enables the practical application of TiO2-based products.Therefore,this work presents a novel nature-inspired strategy to address the challenge of deactivation,and advances the development of photocatalytic technology for environmental remediation.展开更多
基金supported by the National Key Research and Development Project (2016YFC0204702)the National Natural Science Foundation of China (51478070, 21501016, 51108487)+2 种基金the Innovative Research Team of Chongqing (CXTDG201602014)the Natural Science Foundation of Chongqing (cstc2016jcyjA0481)Youth Innovation Promotion Association of Chinese Academy of Sciences (2015316)~~
文摘Heterostructured BiOI@La（OH）3 nanorod photocatalysts were prepared by a facile chemical impregnation method.The enhanced visible light absorption and charge carrier separation can be simultaneously realized after the introduction of BiOI particles into La（OH）3 nanorods.The BiOI@La（OH）3 composites were applied for visible light photocatalytic oxidization of NO in air and exhibited an enhanced activity compared with BiOI and pure La（OH）3 nanorods.The results show that the energy levels between the La（OH）3 and BiOI phases matched well with each other,thus forming a heterojunctioned BiOI@La（OH）3 structure.This band structure matching could promote the separation and transfer of photoinduced electron-hole pairs at the interface,resulting in enhanced photocatalytic performance under visible light irradiation.The photocatalytic performance of BiOI@La（OH）3 is shown to be dependent on the mass ratio of BiOI to La（OH）3.The highest photocatalytic performance can be achieved when the mass ratio of BiOI to La（OH）3 is controlled at 1.5.A further increase of the mass ratio of BiOI weakened the redox abilities of the photogenerated charge carriers.A new photocatalytic mechanism for BiOI@La（OH）3 heterostructures is proposed,which is directly related to the efficient separation of photogenerated charge carriers by the heterojunction.Importantly,the as-prepared BiOI@La（OH）3 heterostructures exhibited a high photochemical stability after multiple reaction runs.Our findings demonstrate that BiOI is an effective component for the formation of a heterostructure with the properties of a wide bandgap semiconductor,which is of great importance for extending the light absorption and photocatalytic activity of wide bandgap semiconductors into visible light region.
基金supported by the National Natural Science Foundation of China(51508055,51502277)Chongqing Postdoctoral Science Foundation(Xm2016020)+2 种基金China Postdoctoral Science Foundation(2016M602660)Natural Science Foundation of Chongqing Science and Technology Commission(cstc2016jcyjA0154)Innovative Research Team of Chongqing(CXTDG201602014)~~
文摘We report a one‐pot surfactant‐free wet‐chemical reduction approach to the synthesis of palladium/titanium nitride(Pd/TiN)and Pd/carbon(Pd/C)composites,in which^5 nm Pd NPs were uniformly dispersed on TiN or C.In terms of catalytic performance,Pd/TiN showed enhanced efficiency and stability compared with those of Pd/C and bare TiN in the electrocatalytic hydrodechlorination(EHDC)reaction of 2,4‐dichlorophenol(2,4‐DCP)in aqueous solution.The superior performance of Pd/TiN arises from the promotion effect of TiN.Strong metal‐support interactions modified the electronic structure of Pd,which optimized generation of H*ads and 2,4‐DCP adsorption/activation.The cathode potential plays a vital role in controlling the EHDC efficiency and the product distribution.A working potential of?0.80 V was shown to be optimal for achieving the highest EHDC efficiency and maximizing conversion of 2,4‐DCP to phenol(P).Our studies of the reaction pathway show that EHDC of 2,4‐DCP on Pd/TiN proceeded by 2,4‐DCP→p‐chlorophenol(p‐CP),o‐chlorophenol(o‐CP)→P;however,Pd/TiN presented little selectivity for cleavage of p‐C‐Cl vs o‐C‐Cl.This work presents a new approach to enhancing Pd performance towards EHDC through the effects of a support.The strategy demonstrated here could also be extended to design highly efficient catalysts for other hydrogenation reactions.
基金supported by the National Natural Science Foundation of China(51708078,21576034)Chongqing Postdoctoral Science Foundation funded project(Xm2016027)the Innovative Research Team of Chongqing(CXTDG201602014,CXTDX201601016)~~
文摘Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.
基金supported by the National Natural Science Foundation of China(21822601,22176029)Excellent Youth Foundation of Sichuan Scientific Committee(2021JDJQ0006)+1 种基金Fundamental Research Funds for the Central Universities(ZYGX2019Z021)111 Project(B20030)。
文摘Dynamic defects on halide perovskite materials,caused by ion dissociation and migration under light illumination,typically result in undesirable energy dissipation and limited energy conversion efficiency.However,in this work,we demonstrated that dynamic halogen defects generated by the same process in bismuth oxyhalide(Bi_(5)O_(7)Cl)materials can act as active sites to promote charge separation and photocatalytic efficiency.Mechanistic studies and density functional theory calculations revealed that dynamic Cl defects affected the electronic structure of Bi_(5)O_(7)Cl and photocatalytic CO_(2)reduction process.As active sites,these defects promoted charge transfer,leading to the activation of adsorbed CO_(2)molecules and reduction of the energy barrier of the rate-determining step.Thus,CO_(2)was spontaneously converted into COOH−intermediate and finally reduced to CO with a high efficiency of 108.60μmol g^(−1) and selectivity of 100%after 4-h of CO_(2)photoreduction.This work is highly instructive and valuable to the exploration of dynamic defects on halide-containing materials applied in solar energy conversion.
基金supported by the National Natural Science Foundation of China(21822601 and 21777011)the Fundamental Research Funds for the Central Universities(ZYGX2019Z021)+2 种基金the 111 Project(B20030)the Plan for“National Youth Talents”of the Organization Department of the Central CommitteeSouthwest Petroleum University Graduate Research Innovation Fund Project(2019cxzd008)。
文摘The accumulation of intermediates or final products on TiO2 during photocatalytic volatile organic compounds(VOCs)degradation is typically neglected,despite the fact that it could result in the block of active sites and the deactivation of photocatalysts.Inspired from the natural formation of stalactite(CaCO3+H2O+CO2←→Ca(HCO3)2),we fabricated CaCO3 loading TiO2 composites(CCT21)to realize the spontaneously transfer of accumulated final products(CO2 and H2O).Efficient and durable performance for gaseous toluene removal has been demonstrated and the cost of photocatalyst is greatly reduced by the comparison of specific activity.The introduction of CaCO3 induces the interaction between TiO2 and CaCO3 to stimulate abundant activated electrons for the improvement on the adsorption and activation of reactants and the transformation of photogenerated carriers,and most importantly,facilitates the transfer of final products to release active sites and thus suppress the deactivation of TiO2.Furthermore,we develop a facile method to immobilize CCT21 powder on flexible support,which greatly reduces the loss of photocatalysts and correspondingly enables the practical application of TiO2-based products.Therefore,this work presents a novel nature-inspired strategy to address the challenge of deactivation,and advances the development of photocatalytic technology for environmental remediation.
