Self-Catalyzed Carbon Dioxide Adsorption by Metal-Organic Chains on Gold Surfaces

摘要

Efficient capture of CO_2 by chemical means requires a microscopic understanding of the interactions of the molecule-substrate bonding and adsorption-induced collective phenomena. By molecule-resolved imaging with scanning tunneling microscopy (STM), we investigate self-catalyzed CO_2 adsorption on one-dimensional (1D) substrates composed of self-assembled metal-organic chains (MOCs) supported on gold surfaces. CO_2 adsorption turns on attractive interchain interactions, which induce pronounced surface structural changes; the initially uniformly dispersed chains gather into close packed bundles, which are held together by highly ordered, single molecule wide CO_2 ranks. CO_2 molecules create more favorable adsorption sites for further CO_2 adsorption by mediating the interchain attraction, thereby self-catalyzing their capture. The release of CO_2 molecules by thermal desorption returns the MOCs to their original structure, indicating that the CO_2 capture and release are reversible processes. The real space microscopic characterization of the self-catalyzed CO_2 adsorption on 1D substrates could be exploited as platform for design of molecular materials for CO_2 capture and reduction.