Enhanced photocatalytic CO₂ reduction activity of Z-scheme CdS/BiVO₄ nanocomposites with thinner BiVO4 nanosheets

【作者】 魏之鹤； 要红昌； 李中军；

【Author】 Zhi-He Wei;Hong-Chang Yao;Zhong-Jun Li;College of Chemistry and Molecular Engineering,Zhengzhou University;

【机构】 College of Chemistry and Molecular Engineering,Zhengzhou University；

【摘要】 Solar photocatalytic conversion of CO₂ with H₂O into valuable chemicals over semiconductor catalysts is an ideal solution to address the increasing energy crisis and the worsening global climate.^[1]Photocatalysts play a crucial role in the conversion process and hence,reasonable construction of Z-scheme photocatalysts has been drawn much attention in the field of CO₂ reduction recently.^[2]Monoclinic bismuth vanadate（m-BiVO₄）is an important visible-light-driven photocatalyst but its low conduction band potential and short electron diffusion lengths（10 nm）limit its application in CO₂ reduction.^[3-4]Herein,we fabricated two kinds of BiVO₄ nanosheets with 15～30 nm and 55～75 nm thickness by controlling the preparation condition of pH value for 2.5 and 6.5.On this basis,a series of efficient CdS/BiVO₄ photocatalysts had been successfully synthesized（Fig.1）and evaluated their photocatalytic activities for CO₂ reduction under visible light irradiation（λ>400 nm）.In Fig.2,the results show that composites exhibit more efficient photocatalytic activity than pure CdS and BiVO₄.Meanwhile,the composites with the substrate 15～30 nm thickness（I-BC-5）have more efficient photocatalytic activity compared to those with 55～75 nm thickness BiVO₄（II-BC-5）.Apart from the increase of the yields,the CdS/BiVO₄ nanocomposites with thinner BiVO₄ substrate are more conducive to the formation of CH₄.The enhanced photoactivity of the composites is attributed to the efficient separation of the photoexcited electron-hole pairs via Z-scheme transfer mode.On the other hand,the results confirm that thinner BiVO₄ nanosheets are more favorable for improved photocatalytic CO₂ reduction due to short electron diffusion lengths.更多还原

【Abstract】 Solar photocatalytic conversion of CO₂ with H₂O into valuable chemicals over semiconductor catalysts is an ideal solution to address the increasing energy crisis and the worsening global climate.^[1]Photocatalysts play a crucial role in the conversion process and hence,reasonable construction of Z-scheme photocatalysts has been drawn much attention in the field of CO₂ reduction recently.^[2]Monoclinic bismuth vanadate（m-BiVO₄）is an important visible-light-driven photocatalyst but its low conduction band potential and short electron diffusion lengths（10 nm）limit its application in CO₂ reduction.^[3-4]Herein,we fabricated two kinds of BiVO₄ nanosheets with 15～30 nm and 55～75 nm thickness by controlling the preparation condition of pH value for 2.5 and 6.5.On this basis,a series of efficient CdS/BiVO₄ photocatalysts had been successfully synthesized（Fig.1）and evaluated their photocatalytic activities for CO₂ reduction under visible light irradiation（λ>400 nm）.In Fig.2,the results show that composites exhibit more efficient photocatalytic activity than pure CdS and BiVO₄.Meanwhile,the composites with the substrate 15～30 nm thickness（I-BC-5）have more efficient photocatalytic activity compared to those with 55～75 nm thickness BiVO₄（II-BC-5）.Apart from the increase of the yields,the CdS/BiVO₄ nanocomposites with thinner BiVO₄ substrate are more conducive to the formation of CH₄.The enhanced photoactivity of the composites is attributed to the efficient separation of the photoexcited electron-hole pairs via Z-scheme transfer mode.On the other hand,the results confirm that thinner BiVO₄ nanosheets are more favorable for improved photocatalytic CO₂ reduction due to short electron diffusion lengths.更多还原