Electrodeposited Nickel Enhanced Alloyed Electrocatalysts for CO2 Reduction

Abstract

The demands of climate change push the need for electrocatalysts capable of CO2 reduction to value-added products at high Faradaic efficiencies. The recent success of different alloyed systems for heterogeneous CO2 reduction encourages research into enhancing already created systems and discovering new combinations of alloys. This work focuses on the nickel enhancement of the known (Cr2O3)3(Ga2O3) electrocatalyst and the undeveloped MnGa2 system. Various glassy carbon substrates were nickel-plated using a Watts bath electrodeposition method. Optimization efforts were made for the nickel-plating procedure. Nickel-plating was most uniform and consistent between 600 -1,800 s. Nickel-plating on glassy carbon was observed at potentials as low as -0.75 V vs Ag/AgCl. (Cr2O3)3(Ga2O3) and MnGa2 were synthesized on the nickel-plated glassy carbon substrate. Bulk electrolysis experiments were undertaken to assess the catalyst’s ability to reduce CO2. The morphology and composition of the deposited nickel with and without the two catalysts were evaluated using SEM and XRD. Ni-enhanced (Cr2O3)3(Ga2O3) yielded 1-butanol at a Faradaic efficiency of 64% along with acetic acid and acetone at a potential -1.45 V vs Ag/AgCl. While (Cr2O3)3(Ga2O3) on electrodeposited nickel yielded methanol, formate, and acetic acid. The MnGa2 on deposited nickel yielded ethanol consistently with a Faradaic efficiency as high as 1.82% along with methanol, acetic acid, and formate at a potential of -1.38 V vs Ag/AgCl. These catalysts in the presence of nickel reduced CO2 to products unknown to these specific systems prior.