Efficient conversion of CO2 to energy-dense, value-added carbon compounds could provide new opportunities for CO2 utilization in environmental applications. An electrochemical process for CO2 reduction is attractive due to its good environmental compatibility and the potential to couple with other clean energy technologies. To date, it is still very challenging to design efficient molecular catalysts with high selectivity for CO2 reduction and good long-term stability. Scalable processes enabling uniform catalytic coatings on flat and non-planar substrates are also missing. Here, we report a novel oxidative chemical vapor deposition (oCVD) process for catalytically active metal-organic covalent network (MOCN) thin films. Porphyrin-based monomers were polymerized and deposited on glassy carbon and carbon paper substrates using our oCVD process. FTIR spectra confirm the crosslinked structure of the MOCN catalyst. The chemical composition and the bonding environment for the metal center were further analyzed by EDX and XPS. SEM images show good conformality of our MOCN films on both flat and non-planar substrates like carbon paper. Compared with unpolymerized cobalt tetraphenylporphyrin films deposited on glassy carbon substrates by thermal evaporation, the crosslinked MOCN films synthesized by oCVD exhibit over 5 times higher CO:H2 product ratio at -0.8V vs. RHE. With MOCN-coated carbon paper, we obtained 1.4 mA/cm2 current density with FECO &gt; 80% at -0.7V vs. RHE. We will discuss how the changes in electron density and symmetry of the metalloporphyrin structure after polymerization enhance the electrocatalytic performance. The solvent-free oCVD process reported here also has great potential for scalable manufacturing.

Chemical vapor deposited metal-organic covalent networks for electrocatalytic CO2 reduction

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.