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.