Jin Jiaqi, Hu Jundie, Qu Jiafu, Cao Guangming, Lei Yan, Zheng Zhi, Yang Xiaogang, Li Chang Ming
Institute of Advanced Cross-field Science, College of Life Science, Qingdao University, Qingdao 266071, P. R. China.
Institute of Materials Science and Devices, School of Material Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, P. R. China.
ACS Appl Mater Interfaces. 2022 Apr 20;14(15):17509-17519. doi: 10.1021/acsami.2c02205. Epub 2022 Apr 6.
The CO reduction reaction (CORR) 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 CORR are very sluggish due to its complicated multiple-step charge transfer reactions. Here, we systematically investigate the charge transfer reaction rate during CO reduction on CuBiO 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 CuBiO are larger than bare CuBiO 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.
CO还原反应（CORR）是自然光合作用和人工光合作用中在碳中性循环中提供碳水化合物食物和碳氢化合物能量的关键步骤。然而，由于其复杂的多步电荷转移反应，目前CORR的太阳能转换效率和/或产物选择性非常低。在这里，我们系统地研究了用3-氨丙基三乙氧基硅烷（APTES）修饰表面的CuBiO光阴极上CO还原过程中的电荷转移反应速率。我们发现表面胺基提高了电荷分离速率，显著增强了表面电荷转移反应速率。然而，表面酸度对一级反应的影响较小，这表明在光电化学电池（PEC）过程的早期存在速率决定步骤（RDS）。此外，强度调制光电流光谱（IMPS）证实，APTES包覆的CuBiO上的表面电荷转移和复合速率均大于裸CuBiO，同时具有相当的电荷转移效率。总体而言，PEC条件下的表面电荷转移反应需要设计更有效的纳米结构光电极和强大的表征方法，以从本质上提高电荷分离和转移速率，同时降低复合速率。
