Catalytic Activity and Product Selectivity Trends for Carbon Dioxide Electroreduction on Transition Metal-Coated Tungsten Carbides

5 years ago

Catalytic Activity and Product Selectivity Trends for Carbon Dioxide Electroreduction on Transition Metal-Coated Tungsten Carbides

Sippakorn Wannakao, Alexie M. Kolpak, Nongnuch Artrith, Jumras Limtrakul

Electrochemical reduction of CO₂ is a promising technology to produce hydrocarbon and alcohol fuels in a carbon neutral cycle. To utilize the technology on a commercial scale, inexpensive and earth-abundant catalysts are needed. Here, we employ density functional theory calculations to investigate activity and product selectivity trends for CO₂ electroreduction reaction on transition metal monolayer coated tungsten carbides, M/WC (M = Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Ir, Pt, and Au). Such core–shell systems have the potential to reduce the loading of precious metals, such as Ag and Au, while the catalytic properties for CO₂-to-CO reduction of metal surfaces remain. We find that at low potentials (<0.5 V) Cu/WC and Pd/WC core–shell particles catalyze CO₂ reduction to CO as the main product due to low COOH formation and CO desorption free energies. Furthermore, we show that the binding energies of the carbo- and oxo-intermediates on the M/WC catalyst surface obey scaling relations with the binding energies of CO and O, respectively. The binding energies of these two key intermediates exhibit linear relationships with the total d-band center of the surface metals; thus, the d-band center can be utilized as a unified electronic-structure-based descriptor to predict the product selectivity. Such a unified descriptor is useful for efficient screening for improved core–shell catalysts. This work illustrates the potential of core–shell metal/metal-carbide particles as a platform for the design of inexpensive CO₂ electroreduction catalysts.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b05741

DOI: 10.1021/acs.jpcc.7b05741