(233a) Elucidating Doping Effects on the Catalytic Activity of Ligand Protected Gold Nanoclusters for the Electrochemical Reduction of CO2

Authors: 
Nagarajan, A. V. - Presenter, University of Pittsburgh
Li, S., Carnegie Mellon University
Alfonso, D., National Energy Technology Laboratory
Kauffman, D. R., National Energy Technology Laboratory
Jin, R., Carnegie Mellon University
Mpourmpakis, G., University of Pittsburgh
Ligand-protected gold nanoclusters (LPNCs) are a novel class of nanomaterials that exhibit atomic structural precision and unique physicochemical properties1. Recently, LPNCs have emerged as promising catalytic nanomaterials, particularly for the electrochemical reduction of CO2 (CO2 RR) to CO and H2 evolution2. In order to further tune the properties of gold-based catalytic materials, surface modification through doping (alloying) has shown promise. Owing to their atomic precision and tunable composition, LPNCs have gained attention as model catalysts for understanding the impact of heterometal doping on catalysis. In this work, we investigated the effect of cadmium (Cd) doping on the catalytic activity of the [Au23(SR)16]1- NC (Au23 NC) and [Au19Cd2(SR)16]1- NC (Au19Cd2 NC). Using density functional theory (DFT) calculations, we unraveled the thermodynamic feasibility of active site formation through partial ligand (-R) removal, which leads to the activation of the Au19Cd2 NC as an electrocatalyst. Furthermore, the formation of CO (from CO2 RR) on the undoped Au23 NC was found to be thermodynamically less favorable than on Au19Cd2 NC by 0.74 eV. Experimental observations show that Cd doping into the Au23 NC enhanced the CO2 RR activity as well as selectivity by twofold at ~ -0.9 V. Moreover, the Au19Cd2 NC exhibited the highest CO2 RR activity among reported gold NCs. With theory and experiments being in excellent agreement, we suggest that Cd doping can boost the CO2 RR performance of gold NCs. Overall, this work offers detailed fundamental understanding of the catalytic mechanism of CO2 RR on heterometal doped LPNCs.

References

  1. Jin, R.; Zeng, C.; Zhou, M.; Chen, Y. Chemical Reviews 2016, 116, (18), 10346-10413.
  2. Austin, N.; Zhao, S.; McKone, J. R.; Jin, R.; Mpourmpakis, G. Catalysis Science & Technology 2018, 8, (15), 3795-3805.