Atomic Ru clusters supported on CeO2(110) for effectively catalyzing the electrochemical N2 reduction reaction: insights from density functional theory

Abstract

In this work, density-functional theory (DFT) was used to investigate the geometry and electronic structure of Ru_n(n = 1–6,10) supported on CeO₂(110) (Ru_n(n = 1–6,10)/CeO₂(110)) and their electrocatalytic properties for the N₂ reduction reaction (NRR). The results indicated that there is a strong metal–support interaction between Ru_n and CeO₂(110), which leads to large surface distortion and stabilized Ru_n. On Ru_n(n = 1–6,10)/CeO₂(110), N₂ captured in the end-on mode is thermodynamically more favorable than that captured in the side-on mode; however, the side-on mode can lead to stronger activation of N₂ which promotes the following protonation step of N₂. For Ru_n(n = 3,5,6)/CeO₂(110), the electrochemical NRR prefers to occur via an enzymatic mechanism with limiting potentials of −0.31, −0.53 and −0.66 V. The electrocatalytic activity of Ru_n(n = 1–6,10)/CeO₂(110) for the NRR shows a strong size dependence. For Ru₃/CeO₂(110), it has the lowest absolute value of limiting potential, and with the increase in n (n > 3), the limiting potential becomes more negative. Moreover, Ru₃/CeO₂(110) shows high selectivity and stability. This study gives valuable insights for designing effective catalysts for the NRR.