Han Bin, Ou Xinwen, Zhong Zuqi, Liang Shujie, Deng Hong, Lin Zhang
School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, 51006, P. R. China.
Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, South China University of Technology, Guangzhou, 510006, P. R. China.
Small. 2020 Sep;16(38):e2002985. doi: 10.1002/smll.202002985. Epub 2020 Aug 18.
Direct photoconversion of low-concentration CO into a widely tunable syngas (i.e., CO/H mixture) provides a feasible outlet for the high value-added utilization of anthropogenic CO . However, in the low-concentration CO photoreduction system, it remains a huge challenge to screen appropriate catalysts for efficient CO and H production, respectively, and provide a facile parameter to tune the CO/H ratio in a wide range. Herein, by engineering the metal sites on the covalent organic frameworks matrix, low-concentration CO can be efficiently photoconverted into tunable syngas, whose CO/H ratio (1:19-9:1) is obviously wider than reported systems. Experiments and density functional theory calculations indicate that Fe sites serve as the H evolution sites due to the much stronger binding affinity to H O, while Ni sites act as the CO production sites for the higher affinity to CO . Notably, the widely tunable syngas can also be produced over other Fe/Ni-based bimetal catalysts, regardless of their structures and supporting materials, confirming the significant role of the metal sites in regulating the selectivity of CO photoreduction and providing a modular design strategy for syngas production.
将低浓度一氧化碳直接光催化转化为具有广泛可调性的合成气（即一氧化碳/氢气混合物），为高附加值利用人为产生的一氧化碳提供了一条可行途径。然而，在低浓度一氧化碳光还原体系中，分别筛选出用于高效生成一氧化碳和氢气的合适催化剂，并提供一个能在宽范围内调节一氧化碳/氢气比例的简便参数，仍然是一个巨大挑战。在此，通过调控共价有机框架基质上的金属位点，低浓度一氧化碳能够被高效光催化转化为可调合成气，其一氧化碳/氢气比例（1:19至9:1）明显比已报道的体系更宽。实验和密度泛函理论计算表明，由于铁位点对水分子具有更强的结合亲和力，因而作为析氢位点，而镍位点对一氧化碳具有更高亲和力，充当一氧化碳生成位点。值得注意的是，无论结构和载体材料如何，其他基于铁/镍的双金属催化剂也能产生具有广泛可调性的合成气，这证实了金属位点在调节一氧化碳光还原选择性方面的重要作用，并为合成气生产提供了一种模块化设计策略。
