Reaction Kinetics of Photoelectrochemical CO2 Reduction on a CuBi2O4-Based Photocathode

Jiaqi Jin; Jundie Hu; Jiafu Qu; Guangming Cao; Yan Lei; Zhi Zheng; Xiaogang Yang; Chang Ming Li

doi:10.1021/acsami.2c02205

Reaction Kinetics of Photoelectrochemical CO₂ Reduction on a CuBi₂O₄-Based Photocathode

ACS Appl Mater Interfaces. 2022 Apr 20;14(15):17509-17519. doi: 10.1021/acsami.2c02205. Epub 2022 Apr 6.

Authors

Jiaqi Jin^{1

2}, Jundie Hu², Jiafu Qu², Guangming Cao^{2

3}, Yan Lei⁴, Zhi Zheng⁴, Xiaogang Yang², Chang Ming Li^{1

2}

Affiliations

¹ Institute of Advanced Cross-field Science, College of Life Science, Qingdao University, Qingdao 266071, P. R. China.
² Institute of Materials Science and Devices, School of Material Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, P. R. China.
³ School of Physics and Technology, Suzhou University of Science and Technology, Suzhou 215009, P. R. China.
⁴ Key Laboratory for Micro-Nano Energy Storage and Conversion Materials of Henan Province, Xuchang University, 88 Bayi Road, Xuchang, Henan 461000, P. R. China.

PMID: 35385644
DOI: 10.1021/acsami.2c02205

Abstract

The CO₂ reduction reaction (CO₂RR) is an essential step in natural photosynthesis and artificial photosynthesis to provide carbohydrate foods and hydrocarbon energy in the carbon-neutral cycle. However, the current solar conversion efficiencies and/or product selectivity of the CO₂RR are very sluggish due to its complicated multiple-step charge transfer reactions. Here, we systematically investigate the charge transfer reaction rate during CO₂ reduction on CuBi₂O₄ photocathodes, where the surface is modified with 3-aminopropyltriethoxysilane (APTES). We discover that the surface amine group increases the charge separation rate, significantly enhancing the surface charge transfer reaction rate. However, the surface acidity has less influence on the first-order reaction, indicating that a rate-determining step (RDS) exists in the early stage of the photoelectrochemical cell (PEC) processes. Moreover, the intensity-modulated photocurrent spectroscopy (IMPS) confirms that both surface charge transfer and the recombination rate on APTES-coated CuBi₂O₄ are larger than bare CuBi₂O₄ while possessing comparable charge transfer efficiencies. Overall, the surface charge transfer reactions under the PEC condition require designing more effective nanostructured photoelectrodes and powerful characterization methods to intrinsically increase the charge separation and transfer rate while reducing the recombination rate.

Keywords: CuBi2O4; amine modification; photoelectrochemical CO2 reduction; rate law; reaction rate.