Atomic Ru clusters supported on CeO 2 (110) for effectively catalyzing the electrochemical N 2 reduction reaction: insights from density functional theory

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 CeO 2 (110) (Ru n ( n = 1–6,10)/CeO 2 (110)) and their electrocatalytic properties for the N 2 reduction reaction (NRR). The results indicated that there is a strong metal–support interaction between Ru n and CeO 2 (110), which leads to large surface distortion and stabilized Ru n . On Ru n ( n = 1–6,10)/CeO 2 (110), N 2 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 N 2 which promotes the following protonation step of N 2 . For Ru n ( n = 3,5,6)/CeO 2 (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)/CeO 2 (110) for the NRR shows a strong size dependence. For Ru 3 /CeO 2 (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, Ru 3 /CeO 2 (110) shows high selectivity and stability. This study gives valuable insights for designing effective catalysts for the NRR.