Zhu Shan, Li Xiaodong, Jiao Xingchen, Shao Weiwei, Li Li, Zu Xiaolong, Hu Jun, Zhu Junfa, Yan Wensheng, Wang Chengming, Sun Yongfu, Xie Yi
Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, P. R. China.
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, P. R. China.
Nano Lett. 2021 Mar 10;21(5):2324-2331. doi: 10.1021/acs.nanolett.1c00383. Epub 2021 Mar 1.
Selective CO photoreduction into a high-energy-density C product is still challenging. Here, charge-polarized metal pair sites are designed to trigger C-C coupling through manipulating asymmetric charge distribution on the reduction intermediates. Taking the synthetic partially reduced CoO nanosheets as an example, theoretical calculations unveil the asymmetric charge distribution on surface cobalt sites. The formed charge-polarized cobalt pair sites not only donate electrons to CO molecules but also accelerate the coupling of asymmetric COOH* intermediates through lowering the energy barrier from 0.680 to 0.240 eV, affirmed by quasi X-ray photoelectron spectroscopy and Gibbs free energy calculations. Also, the electron-rich cobalt sites strengthen their interaction with O of the HOOC-CHO* intermediate, which favors the C-O bond cleavage and hence facilitates the rate-limiting CHCOOH desorption process. The partially reduced CoO nanosheets achieve 92.5% selectivity of CHCOOH in simulated air, while the CO-to-CHCOOH conversion ratio is 2.75%, obviously higher than that in pure CO.
将一氧化碳选择性光还原为高能量密度的碳产物仍然具有挑战性。在此，设计了电荷极化的金属对位点，通过操纵还原中间体上的不对称电荷分布来触发碳-碳偶联。以合成的部分还原的氧化钴纳米片为例，理论计算揭示了表面钴位点上的不对称电荷分布。形成的电荷极化钴对位点不仅向一氧化碳分子提供电子，还通过将能垒从0.680电子伏特降低到0.240电子伏特来加速不对称羧基自由基中间体的偶联，准X射线光电子能谱和吉布斯自由能计算证实了这一点。此外，富电子的钴位点增强了它们与HOOC-CHO*中间体中氧的相互作用，这有利于碳-氧键的断裂，从而促进限速的CHCOOH解吸过程。在模拟空气中，部分还原的氧化钴纳米片实现了92.5%的CHCOOH选择性，而CO到CHCOOH的转化率为2.75%，明显高于纯CO中的转化率。
