### Ni离子替位掺杂TiO2增强光热化学循环还原CO2研究

1. a 浙江大学 能源清洁利用国家重点实验室 杭州 310027;
b 浙江北仑发电有限公司 宁波 315000
• 投稿日期:2017-03-02 发布日期:2017-06-08
• 通讯作者: 张彦威 E-mail:zhangyw@zju.edu.cn
• 基金资助:

国家自然科学基金创新研究群体项目（No.51621005），国家自然科学基金（No.51276170）与中央高校基本科研业务费专项资金（No.2017FZA4014）资助项目.

### Photo-thermochemical Cycle for CO2 Reduction based on Effective Ni ion Substitute-doped TiO2

Xu Chenyua, Lin Jiayia, Pan Fuqianga, Deng Bowena, Wang Zhihuaa, Zhou Junhua, Chen Yunb, Ma Jingchengb, Gu Zhienb, Zhang Yanweia

1. a State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027;
b Zhejiang Beilun Power Generation Co., Ningbo 315000
• Received:2017-03-02 Published:2017-06-08
• Contact: 10.6023/A17030083 E-mail:zhangyw@zju.edu.cn
• Supported by:

Project supported by the Innovative Research Groups of the National Natural Science Foundation of China (No.51621005),National Natural Science Foundation of China (No.51276170) and the Fundamental Research Funds for the Central Universities (No.2017FZA4014).

To study the mechanism of the photo-thermochemical cycle (PTC),titanium dioxide (ST) and Ni-doped TiO2(NT) films were produced using a sol-gel method and applied in the PTC for CO2 reduction.And commercial P25(PT) has been used as a compared sample.A comparison of CO production shows that Ni-doped TiO2 performed better than undoped TiO2 and P25.Average CO production of NT PTCs was 5.30 μmol/g-cat and it was nearly 3.13 times of ST PTCs'CO production and 2.28 times of PT PTCs'.Scanning electron microscopy (SEM),transmission electron microscopy (TEM),energy-dispersive X-ray spectroscopy (EDXS) and X-ray diffraction (XRD) were used to assess the crystal structure and morphology of the films.Ni element could be found in NT by EDXS and inductively coupled plasma-atomic emission spectrometry (ICP-AES),and the mass fraction of Ni was 0.54% and 0.436% which were agreed with experiments.This result of XRD indicated that Ni2+ may have high dispersion without significant change in TiO2 and Ni2+ ions were doped into the TiO2 lattice so that Ni-O-Ti bonds were formed.Photoluminescence (PL),time-resolved PL,UV-visible diffuse reflectance spectra (UV-visible DRS) and X-ray photoelectron spectroscopy (XPS) analyses were also conducted to investigate the charge transfer and reaction mechanisms on the sample surface.The incorporation of Ni into TiO2 resulted in a weaker PL intensity than that of bare TiO2,which suggests that the introduction of Ni into TiO2 effectively suppressed the undesirable recombination of electrons and holes.According to UV-visible DRS results,the Eg of PT is approximately 3.07 eV,which is smaller than that of ST (Eg=3.23 eV) and PT (Eg=3.20 eV).The narrower band gap of NT indicates that NT absorbed light with a wider wavelength range than that absorbed by ST and PT.By XPS patterns,the increase of Ni+/0 and Ti3+ indicated that the VO may have been produced on the bond of Ni-O-Ti after UV illumination,and oxygen vacancies (VO) have been consumed after thermal step in PTC.Density functional theory (DFT) calculations related to the anatase (101) surface of TiO2 and Ni doped TiO2 was performed to verify and provide guidance for enhancing the PTC mechanism.Single and second VO formation energy have been calculated.The Ni-doped surface exhibits better performance than the undoped surface in the first step in PTC,because of its lower VO formation energy which produce more VO sites.Density of states (DOS) and partial density of states (PDOS) results indicated that narrow energy gap and impurity energy level of Ni-doped TiO2 may lead to a wider wavelength range of NT.As a result,several key factors of the mechanism have been clarified.