Unraveling the Role of CuO Surface Lewis Acid‐Base Pairs in the Initial N─H Bond Cleavage of NH 3 : A DFT Study

ABSTRACT CuO is widely studied as a catalyst for ammonia catalytic combustion due to its good performance and high N 2 selectivity. During catalysis, surface Cu exists in different valence states, which correspondingly modulates the local chemical environment. To elucidate how these variations affect reactivity, first‐principles calculations were used to systematically investigate the cracking mechanism of the initial dehydrogenation step (NH 3 → NH 2 + H) of ammonia molecules on three typical copper‐based surfaces: pristine CuO (111), CuO (111) with an oxygen vacancy (CuO x‐1 ), and metallic Cu (111). The results show that the pristine CuO surface exhibits the highest catalytic activity with the lowest reaction energy barrier of 115.78 kJ·mol −1 , followed by metallic Cu (173.66 kJ·mol −1 ), while the defective CuO x‐1 surface shows the highest barrier (187.38 kJ·mol −1 ). Mechanistically, the superior performance of pristine CuO originates from the synergistic Lewis acid (Cu 2+ )‐Lewis base (O 2− ) pair. These findings elucidate, at the atomic scale, that the cooperative Lewis acid‐base functionality serves as the dominant descriptor governing NH 3 activation. It clearly highlights the advantage of the pristine CuO surface structure in promoting N─H bond cleavage and provides a theoretical basis for rational design of copper‐based catalysts toward efficient ammonia combustion.