(191f) Investigating Mixed Metal Oxides As Cathode Electrocatalysts for CO2 reduction in Solid Oxide Electrolysis Cell

Devising approaches to minimize CO₂ emissions are imperative toward reducing effects from global warming. Solid oxide electrolysis cells (SOECs) provide an efficient way to convert CO₂ or mixed streams of CO₂ and H₂O into high energy molecules, such as CO and H₂. Metallic Ni based-cathode electrocatalysts are the state-of-the-art for CO₂ reduction in SOECs, but suffer from loss in activity under reaction conditions due to coking and their poor redox stability.¹ Mixed ionic and electronic conducting (MIEC) oxides belonging to the perovskite family have been explored as promising alternatives because they can alleviate challenges with coking and redox stability, and in addition they can accommodate >90% of the metals in the periodic table in their structure giving rise to a vast phase space to tune catalytic performance.^2-3 While promising, limiting understanding exists on the factors that govern their electrochemical activity toward CO₂ reduction preventing to enhance their performance. Herein, we probe the factors that govern the electrocatalytic activity of perovskite oxides for CO₂ reduction through studying the effects of the nature of B-site on their electrochemical activity and stability for a series of perovskite compositions (LaBO₃; B=Cr, Mn, Fe, Co and Ni). We correlate the effects of the B-site composition on the oxide surface reducibility and adsorption/activation energetics of CO₂ using a combination of temperature programmed reduction (TPR) experiments and CO₂ desorption studies (TPD) along with characterization via X-ray photoelectron spectroscopy (XPS). Based on these insights, we discuss characteristics of perovskites that control their electrochemical activity for electrochemical CO₂ reduction in SOECs.

References:

1. Carneiro, J.; et al. Industrial & Engineering Chemistry Research 2020, 59 (36), 15884-15893.
2. Zheng, Y.; et al. Chemical Society Reviews 2017, 46 (5), 1427-1463.
3. Gu, X.-K.; et al. Journal of the American Chemical Society 2018, 140 (26), 8128-8137.