Proton adsorption is a key elementary step in promising electrochemical reactions such as hydrogen evolution, CO2 reduction, and ammonia synthesis. Electrocatalyst that are able to promote such reactions selectively should provide favorable adsorption sites which can stabilize reaction intermediates and promote favorable charge transfer kinetics. In this work, we evaluate the effect of tuning the surface electronic structure by changing chalcogen composition in Chevrel Phases chalcogenides Mo6X8 (X=S, Se, Te). These binary chalcogenides were synthesized successfully via microwave-assisted synthesis and their ability to stabilize proton adsorption was studied under relevant conditions for hydrogen production in acidic media. Electrochemical characterization shows that increasing the electronegativity of the chalcogen increases the hydrogen adsorption strength owing to an increase in the Lewis basicity of the chalcogen. The activity of Mo6S8 is further enhanced by decreasing particle size to the nanometer scale using a templated growth approach. The well-defined cubic shape obtained by this method provides a higher abundance of weakly coordinated surface adsorption sites and reduces the charge transfer resistance for proton reduction compared to bulk Mo6S8. The results presented herein provide materials design principles to improve proton adsorption in metal chalcogenide systems and increase selectivity in various electrochemical reactions.

Stabilizing proton adsorption in Mo6X8 (X=S, Se, Te): Effect of chalcogen composition and morphology

ACS Spring Meeting 2021

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