Growing concern on the escalating anthropogenic carbon footprint urges all countries around the world to chart their carbon neutrality plans, in which using renewable electricity to convert CO2 into value-added chemicals is highly tempting and promising. Converting CO2 into value-added products via sustainable energy, such as electrical energy, has several advantages. First, it is one of the most promising routes to close the carbon loop and plays a crucial role in significantly reducing the CO2 concentration in the atmosphere. Second, it can utilize CO2 as a valuable industry reactant that can store energy by converting electrical energy to chemical energy. This necessitates the development of high-performance electrocatalysts for CO2 reduction reactions (CO2RR). In this context, tremendous efforts have been devoted to the design and engineering of a wide category of CO2RR catalysts targeted for selectively producing C1 small molecules, C2+ hydrocarbons, and oxygenated multicarbon products, but significant advances remain to be made on optimizing catalyst activity, selectivity, and stability, as well as maximizing the techno-economic merit. For that, a profound understanding of the catalytic process dictated by explicit catalyst structure is imperative for realizing productorientated catalyst design and development.
Among the diverse electrocatalysts explored for CO2RR, metalorganic frameworks (MOFs) represent a unique category with well-defined and tunable topologic/chemical structure comprising atomically isolated active sites that not only facilitate charge transfer and mass transport, but also help furnish mechanistic understanding on the catalytic process. Recently, the research group of Prof. Tao Cheng, Prof. Yang Peng and Prof. William A. Goddard III set out to impregnate Au nanoneedles into the Zirconium-based PCN-222 MOF to assess its performance as a CO2RR catalyst. to exploit the embedded Au as a high-effificiency CO generator, and the Cu-N4 active sites in the metalloporphyrins to relay and convert CO further into >2e- hydrocarbon products with high selectivity. Through extensive post-electrolytic and operando characterizations, in conjunction with DFT modeling, the enhanced C–C coupling on AuNN@PCN-222(Cu) was ascribed to a tandem mechanism, where CO generated from the impregnated Au nanoneedles are adducted to *CHO on the metalloporphyrins with Au-activated N motifs. Additionally, its enhanced structural stability during CO2RR can be attributed to an altered charge conduction path bypassing the MOF reticular network. By impregnating metal nanostructures into the PCN framework and activating the metalloporphyrin centers, this study sheds new light on boosting the C2+ selectivity and catalytic stability by exquisite catalyst design and synthesis.
The first author: Xie Xulan, Zhang Xiang, Xie Miao
Link to paper: https://www.nature.com/articles/s41467-021-27768-6
Link to Prof. Tao Cheng's group: https://cheng-group.xyz/
Acknowledgement: This work is supported by National Natural Science Foundation of China (Nos. 22072101, 22075193, 21903058), Natural Science Foundation of Jiangsu Province (No. BK20211306), National Key R&D Program of China (Grant no. 2020YFB1505703 and 2020YFA0406103), Natural Science Foundation of Jiangsu Higher Education Institutions (SBK20190810), Six Talent Peaks Project in Jiangsu Province (No. TD-XCL-006), and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions. This work was supported by the Project of Jiangsu Engineering Laboratory of New Materials for Sewage Treatment and Recycling, Soochow University (No. SDGC2126). This work was also partly supported by the Collaborative Innovation Center of Suzhou Nano Science & Technology. W.A.G. gratefully acknowledges support from the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Offifice of Science, Offifice of Basic Energy Sciences, Fuels from Sunlight Hub under award number DE-SC0021266.
Editor: Guo Jia