TY - JOUR
T1 - Copper and iodine co-modified TiO 2 nanoparticles for improved activity of CO 2 photoreduction with water vapor
AU - Zhang, Qianyi
AU - Gao, Tingting
AU - Andino, Jean
AU - Li, Ying
N1 - Funding Information:
This work was supported by the University of Wisconsin-Milwaukee Research Foundation Bradley Catalyst Grant ( 133-PRJ38QV ) and the National Science Foundation (Award# 1067233 and Award # 1067340 ). The authors also gratefully acknowledge access to the shared facilities at the LeRoy Eyring Center for Solid State Science at Arizona State University for some of the characterization work that is reported.
PY - 2012/7/23
Y1 - 2012/7/23
N2 - Copper and iodine co-modified TiO 2 nanoparticles (Cu-I-TiO 2) were synthesized through a combined hydrothermal and wet-impregnation process. The structures and properties of the catalysts were characterized by XRD, BET, SEM/EDX, XPS, and UV-vis diffuse reflectance spectroscopy. Iodine ions were doped in the TiO 2 lattice by replacing Ti 4+ and, consequently, Ti 3+ was generated to balance the charge. Iodine doping reduced the TiO 2 crystal size and was responsible for visible light absorption. Cu species were found to deposit on the surface of TiO 2 and resulted in a slightly increased particle size. The activity of the Cu-I-TiO 2 catalyst was investigated by the photocatalytic reduction of CO 2 with water vapor, and CO was found to be the major reduction product with trace amounts of CH 4 generated. Under UV-vis irradiation, the activity of the co-modified catalyst (Cu-I-TiO 2) was higher than that of the single ion-modified catalysts (Cu-TiO 2 or I-TiO 2). Under visible light irradiation, the addition of Cu to I-TiO 2 did not lead to significant improvements in CO 2 reduction. Methyl chloride (CH 3Cl) was detected as a reaction product when CuCl 2 was used as the precursor in the synthesis, thus suggesting that methyl radicals are reaction intermediates. When CuCl 2 was used as the Cu precursor, a three-fold increase in CO 2 photoreduction activity was observed, as compared to when Cu(NO 3) 2 was used as the Cu precursor. These differences in activities were probably due to enhanced Cu dispersion and the hole-scavenging effects of the Cl ions. However, the formation of by-products (e.g., CH 3Cl) may be undesirable.
AB - Copper and iodine co-modified TiO 2 nanoparticles (Cu-I-TiO 2) were synthesized through a combined hydrothermal and wet-impregnation process. The structures and properties of the catalysts were characterized by XRD, BET, SEM/EDX, XPS, and UV-vis diffuse reflectance spectroscopy. Iodine ions were doped in the TiO 2 lattice by replacing Ti 4+ and, consequently, Ti 3+ was generated to balance the charge. Iodine doping reduced the TiO 2 crystal size and was responsible for visible light absorption. Cu species were found to deposit on the surface of TiO 2 and resulted in a slightly increased particle size. The activity of the Cu-I-TiO 2 catalyst was investigated by the photocatalytic reduction of CO 2 with water vapor, and CO was found to be the major reduction product with trace amounts of CH 4 generated. Under UV-vis irradiation, the activity of the co-modified catalyst (Cu-I-TiO 2) was higher than that of the single ion-modified catalysts (Cu-TiO 2 or I-TiO 2). Under visible light irradiation, the addition of Cu to I-TiO 2 did not lead to significant improvements in CO 2 reduction. Methyl chloride (CH 3Cl) was detected as a reaction product when CuCl 2 was used as the precursor in the synthesis, thus suggesting that methyl radicals are reaction intermediates. When CuCl 2 was used as the Cu precursor, a three-fold increase in CO 2 photoreduction activity was observed, as compared to when Cu(NO 3) 2 was used as the Cu precursor. These differences in activities were probably due to enhanced Cu dispersion and the hole-scavenging effects of the Cl ions. However, the formation of by-products (e.g., CH 3Cl) may be undesirable.
KW - CO reduction
KW - Copper
KW - Iodine
KW - Photocatalysis
KW - Solar energy
KW - TiO
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U2 - 10.1016/j.apcatb.2012.04.035
DO - 10.1016/j.apcatb.2012.04.035
M3 - Article
AN - SCOPUS:84861332043
SN - 0926-3373
VL - 123-124
SP - 257
EP - 264
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
ER -