Enhanced CH4 yield by photocatalytic CO2 reduction using TiO2 nanotube arrays grafted with Au, Ru, and ZnPd nanoparticles

作     者：Piyush Kar Samira Farsinezhad Najia Mahdi Yun Zhang Uchenna Obuekwe Himani Sharma Jing Shen Natalia Semagina Karthik Shankar 

作者机构：Department of Electrical and Computer Engineering University of Alberta 9107-116 Street Edmonton Alberta T6G 2V4 Canada Department of Chemical & Materials Engineering University of Alberta 9107-116 Street Edmonton Alberta T66 2V4 Canada NRC National Institute for Nanotechnology 11421 Saskatchewan Dr. NW Edmonton Alberta T6G 2M9 Canada 

出 版 物：《Nano Research》 (纳米研究（英文版）)

年 卷 期：2016年第9卷第11期

页      面：3478-3493页

核心收录：

学科分类：07[理学] 

基　　金：NSERC Canada School of Energy and the Environment NRC-NINT CMC Microsystems Alberta Innovates Technology Futures 

主　　题：metal nanoparticles (NPs) TiO2 nanotube arrays(TNAs) colloidal synthesis band bending built-in potential photocatalytic CO2reduction semiconductorheterojunctions 

摘      要：Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In this regard, we report here enhanced CH4 formation rates of 25 and 60 μmol·g^-1·h^-1 by photocatalytic CO2 reduction using hitherto unused ZnPd NPs as well as Au and Ru NPs. The NPs are formed by colloidal synthesis and grafted onto short n-type anatase TiO2 nanotube arrays （TNAs）, grown anodically on transparent glass substrates. The interfacial electric fields in the NP-grafted TiO2 nanotubes were probed by ultraviolet photoelectron spectroscopy （UPS）. Au NP-grafted TiO2 nanotubes （Au-TNAs） showed no band bending, but a depletion region was detected in Ru NP-grafted TNAs （Ru-TNAs） and an accumulation layer was observed in ZnPd NP-grafted TNAs （ZnPd-TNAs）. Temperature programmed desorption （TPD） experiments showed significantly greater CO2 adsorption on NP-grafted TNAs. TNAs with grafted NPs exhibit broader and more intense UV-visible absorption bands than bare TNAs. We found that CO2 photoreduction by nanoparticle-grafted TNAs was driven not only by ultraviolet photons with energies greater than the TiO2 band gap, but also by blue photons close to and below the anatase band edge. The enhanced rate of CO2 reduction is attributed to superior use of blue photons in the solar spectrum, excellent reactant adsorption, efficient charge transfer to adsorbates, and low recombination losses.