Compositional Control of Multidimensional Metal Sulfide Electrocatalysts to Drive CO₂ and CO Reduction to Alcohols

The dichotomy of increasing energy demands and carbon emissions is imperative in energy-related research efforts that demand the development of new materials capable of addressing these concerns. An emerging technical avenue in this area is the conversion of vastly abundant renewable energy sources that can be harnessed and directed towards the synthesis of traditionally fossil fuel-based products from atmospheric feedstocks like CO₂. To this end, our work establishes structure—function relationships for materials within the versatile classes of MX₂ (M = Mo, W; X = S, Se) and Chevrel-Phase (CP) M<i>_y</i>Mo₆X₈ (M = alkali, alkaline, transition or post-transition metal; y = 0-4; X = S, Se, Te) chalcogenides. The molybdenum sulfide structures from both families exhibit exceptional promise as CO₂R catalysts which can be accessed through synthesis techniques, such as hydrothermal or solid-state methods, that allow for control over the composition of these materials. Additionally, the use of membrane electrode assemblies (MEA) with molybdenum sulfide structures can maximize CO₂ interactions with the catalyst leading to improved efficiencies toward selective alcohol production. Furthermore, CP catalyst framework is selective towards the electrochemical reduction of CO₂ and CO to methanol (only major liquid-phase product) under applied potentials as mild as -0.4 V vs RHE. This reactivity toward the electrochemical reduction of CO₂ and CO to methanol is correlated with an increased population of chalcogen states, as confirmed via X-Ray Absorption Spectroscopy. Overall, this work seeks to unravel optimally reactive novel small-molecule reduction catalyst compositions.