Session: Electrochemistry and Electrocatalysis:

Each year, trillions of tons of Haber-Bosch fertilizers are required to maintain global feedstocks. Booming populations increase industrial demands for Haber-Bosch ammonia, which in turn fuels agriculture and construction. Though the world relies on the Haber-Bosch process for growth and sustenance, harmful nitrogen oxyanion (NO_x) waste generated as byproducts threaten the health of aquatic ecosystems. Nitrogen oxides such as NO₃^–feed cyanobacterial overgrowths, creating hypoxic and unlivable waters. Transition metal electrocatalysts can selectively reduce these water-soluble NO_x compounds in aqueous conditions, without destruction of the catalyst. Here, graphitic electrode surfaces have been modified with the molecular catalyst cobalt (II) tetraphenylporphyrin (CoTPP). The CoTPP macrocycle was immobilized through π-stacking on multi-walled carbon nanotubes (MWCNT) to create a hybrid electrocatalytic system, which was then drop-casted onto the electrode surface. Remarkably, this hybrid system reduces nitrate in the presence of competitive buffer anions. Preliminary work with a similar graphene-CoTPP hybrid shows promise toward composite characterization and scalability. Future studies aim to optimize robust ammonia production from nitrate in buffer and probe buffer anion and counter-cation influence on Faradaic efficiency.

Electrocatayltic activity of the CoTPP-MWCNTs hybrid system in pH 7 phosphate buffer

Electrocatayltic activity of the CoTPP-MWCNTs hybrid system in pH 7 phosphate buffer

Jeremy Smith

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