Combining Cu2+ /Cu0 Clusters with Fe-N-C for Tandem CO2 Electrocatalytic Reduction: Stability Study via Operando ICP-MS

International audienceThe development of a clean and sustainable energy scenario is crucial in the post-fossil fuel energy transition. The electrocatalytic reduction of CO2, coupled with renewable energy sources, is one of the most efficient routes for the generation of clean fuels and higher value-added chemicals. Copper, so far, is the only metal electrocatalyst capable of reducing CO/CO2 to C1 and C2+ products, such as hydrocarbons, methane, ethylene and ethanol at decent selectivity and productivity. However, this metal presents low selectivity towards a single product. Additionally, the electrode deactivates in operating conditions, mainly due to its intrinsic dynamic behavior and carbon deposits generated by some reaction intermediates [1]. On the other hand, electrocatalysts that reduce CO2 to CO, such as single iron (Fe) atoms embedded in nitrogendoped carbon matrix (labeled Fe-N-C, with Fe = iron, N = nitrogen and C = carbon), have shown high efficiency and activity for CO2-to-CO conversion in water [2]. Furthermore, the electroreduction of CO on copper presents higher faradaic efficiencies for the formation of hydrocarbons and/or alcohols. The aim of this study was to synthesize Cu 2+-doped Fe-N-C single atom catalysts (Cu 2+ suffers in-situ reduction to metallic copper clusters at low potentials [3]) in order to increase the selectivity of copper via tandem effect. In this case, which comprises the CO2-to-CO reduction at stable Fe-N-C sites, and subsequent electroreduction of CO on copper clusters, formed at low electrode potentials. Herein, we investigated the stability/degradation of copper species within the N-doped material under the CO2 reduction reaction conditions by combining transmission electron microscopy (TEM), differential electrochemical mass spectrometry (DEMS), and in-situ inductively-coupled plasma mass spectrometry (ICP-MS).[1] JUNG, H.; LEE, S. Y.; LEE, C. W.; CHO, M. K.; WON, D. H.; KIM, C.; OH, H. S.; MIN, B. K.; HWANG, Y. J. Electrochemical fragmentation of Cu2O nanoparticles enhancing selective C–C coupling from CO2 reduction reaction. Journal of the American chemical society, 2019, v. 141, n. 11, p. 4624-4633.[2] HU, X. M.; HVAL, H. H.; BJERGLUND, E. T.; DALGAARD, K. J.; MADSEN, M. R.; POHL, M. M.; WELTER, E.; LAMAGNI, P.; BUHL, K. B.; BREMHOLM, M.; BELLER, M.; PEDERSEN, S. U. SKRYDSTRUP, T.; DAASBJERG, K. Selective CO2 reduction to CO in water using earth-abundant metal and nitrogen-doped carbon electrocatalysts. ACS Catalysis, 2018, v. 8, n. 7, p. 6255-6264.[3] PAUL, S.; KAO, Y. L.; NI, L.; EHNERT, R.; HERRMANN-GEPPERT, I.; VAN DE KROL, R.; BOGDANOFF, P. Influence of the metal center in M–N–C catalysts on the CO2 reduction reaction on gas diffusion electrodes. ACS Catalysis, 2021, v. 11, n. 9, p. 5850-5864