Electrochemical transformation of CO2 into energy-dense fuels may prove key towards the realization of economically viable, renewable fuels. However, the rational design of CO2 reduction catalysts guided by well-grounded chemical intuition or first-principles computational approaches, have so far been met with limited success. To address this important question of how to activate a molecule as stable and unreactive as CO2 and convert it into complex hydrocarbons, there may be no better place to look than biological systems capable of CO2 activation, for crucial guidance and inspiration.
Recent findings have demonstrated the utility of MoS2 and MoSe2 edge sites in catalyzing the transformation of CO2 to CO. Although this is a promising start, CO is not an easy product to work with industrially nor to transport due to its gaseous nature. Meanwhile, a close look of formate dehydrogenase (FDH), the key enzyme in formate metabolism which catalyzes the reversible two-electron oxidation of formate or reduction of CO2, reveals a catalytic center that is defined by Mo4+/6+ or W4+/6+ coordination with sulfide ligands (from molybdopterin prosthetic groups and cysteine residues) and a selenocysteine side chain. Translation of these chemical moieties, which are recognized as integral to the FDH's architecture and functions, into solid-state semiconductor devices, would suggest that the inclusion of Se ions in Mo/WS2 semiconductors as a dopant may promote the preferred generation of liquid formate, rather than gaseous CO, from CO2. In this project, we want to explore interstitial Se doping of W/MoS2 materials as potential CO2 reduction cathodes, with the ultimate goal of generating reduced liquid hydrocarbon products.