To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve...To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging.In this work,a well-designed nanosheet-based rodlike step-scheme(S-scheme)heterojunction Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with rich oxygen vacancies(OVs)(Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2)-OV)was easily synthesized by calcining BiOAc0.6Br0.2I0.2(Ac-=CH3 COO-)precursor.The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline(TC)and dye rhodamine B(Rh B)degradation and removal rate reached 90.2% and 97.0%within 120 min,respectively,which was higher than those of Bi4O5I2-OV(56.8% and 71.8%),Bi4O5Br2-OV(47.4%and 68.4%),solid solution BiOAc0.6Br0.2I0.2(67.0% and 84.0%)and Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with poor oxygen vacancies(Bi4O5I2/Bi4O5Br2-P)(30.6%and 40.4%).Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac-,it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides,which thus decreased particle size and increased surface areas,but also introduce surface OVs,which could trap photoelectrons and inhibit the recombination of carriers.In addition,the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials,which facilitates charge carriers transfer at the interfaces.The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and Rh B in actual wastewater or in the presence of some electrolytes.This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.展开更多
运用热重-差热-红外-质谱联用(TG-DSC-IR-MS)技术研究了酚醛泡沫(PF)在空气气氛下的热解特性。结果表明:PF在空气气氛中的热解主要分为两个阶段。第一阶段失重率较小,主要为H_2O、HCHO等小分子气体的物理性逸出;在第二阶段,PF首先与空...运用热重-差热-红外-质谱联用(TG-DSC-IR-MS)技术研究了酚醛泡沫(PF)在空气气氛下的热解特性。结果表明:PF在空气气氛中的热解主要分为两个阶段。第一阶段失重率较小,主要为H_2O、HCHO等小分子气体的物理性逸出;在第二阶段,PF首先与空气中的氧反应,逐渐生成炭化层,并出现小幅增重,同时生成H_2O、CO_2、CO、C_2H_4、C、HCHO以及C_2H_5OH等物质,之后PF发生较为剧烈的热分解,大量生成CO_2、CO、C_2H_4等物质(PF的失重主要集中在这一阶段,并且失重速率在506.3℃达到最快)。另外,运用Ozawa-Flynn-Wall法得到分解活化能与转化率的关系曲线,并由之计算出PF在空气气氛中的平均分解活化能为8.56 k J/mol。展开更多
文摘To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging.In this work,a well-designed nanosheet-based rodlike step-scheme(S-scheme)heterojunction Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with rich oxygen vacancies(OVs)(Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2)-OV)was easily synthesized by calcining BiOAc0.6Br0.2I0.2(Ac-=CH3 COO-)precursor.The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline(TC)and dye rhodamine B(Rh B)degradation and removal rate reached 90.2% and 97.0%within 120 min,respectively,which was higher than those of Bi4O5I2-OV(56.8% and 71.8%),Bi4O5Br2-OV(47.4%and 68.4%),solid solution BiOAc0.6Br0.2I0.2(67.0% and 84.0%)and Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with poor oxygen vacancies(Bi4O5I2/Bi4O5Br2-P)(30.6%and 40.4%).Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac-,it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides,which thus decreased particle size and increased surface areas,but also introduce surface OVs,which could trap photoelectrons and inhibit the recombination of carriers.In addition,the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials,which facilitates charge carriers transfer at the interfaces.The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and Rh B in actual wastewater or in the presence of some electrolytes.This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.
文摘运用热重-差热-红外-质谱联用(TG-DSC-IR-MS)技术研究了酚醛泡沫(PF)在空气气氛下的热解特性。结果表明:PF在空气气氛中的热解主要分为两个阶段。第一阶段失重率较小,主要为H_2O、HCHO等小分子气体的物理性逸出;在第二阶段,PF首先与空气中的氧反应,逐渐生成炭化层,并出现小幅增重,同时生成H_2O、CO_2、CO、C_2H_4、C、HCHO以及C_2H_5OH等物质,之后PF发生较为剧烈的热分解,大量生成CO_2、CO、C_2H_4等物质(PF的失重主要集中在这一阶段,并且失重速率在506.3℃达到最快)。另外,运用Ozawa-Flynn-Wall法得到分解活化能与转化率的关系曲线,并由之计算出PF在空气气氛中的平均分解活化能为8.56 k J/mol。
