Urea oxidation, a key process in energy and environmental science, faces challenges because of the insu cient understanding of its mechanism and the lack of e cient catalysts. Here we demonstrate that nickel ferrocyanide (Ni 2 Fe(CN) 6 ) molecular catalyst supported on Ni form can drive urea oxidation reaction (UOR) with the record electrochemical activity and stability among all supported catalysts reported so far. A combination of kinetics data, in-situ spectroscopic measurements and energy computations suggests a new UOR pathway that delivers such outstanding performance. Different from most studied Ni-based catalysts with NiOOH derivative as a real catalytically active site for UOR, Ni 2 Fe(CN) 6 appears to be a next-generation catalyst able to directly facilitate a two-step reaction pathway involving a critical reaction of intermediate ammonia's production (on Ni site) and oxidation (on Fe site).Due to the alternative rate-determining step with a more favorable thermal energetics, Ni 2 Fe(CN) 6 broke the limiting activity of the reported so far UOR catalysts. As a result, the UOR process on Ni 2 Fe(CN) 6 can replace conventional water oxidation process in various energy-saving systems for hydrogen and hydrogen peroxide production.

The energetics and growth kinetics of graphene edges during CVD growth on Cu(111) and other catalyst surfaces are explored by density functional theory (DFT) calculations. Different from graphene edges in vacuum, the reconstructions of both armchair (AC) and zigzag (ZZ) edges are energetically less stable because of the passivation of the edges by the catalytic surface. Furthermore, we predicated that, on the most used Cu(111) catalytic surface, each AC-like site on the edge is intended to be passivated by a Cu atom. Such an unexpected passivation significantly lowers the barrier of incorporating carbon atoms onto the graphene edge from 2.5 to 0.8 eV and therefore results in a very fast growth of the AC edge. These theoretical results are successfully applied to explain the broad experimental observations that the ZZ egde is the dominating edge type of growing graphene islands on a Cu surface.

Ground-state structures of supported C clusters, C(N) (N = 16, ..., 26), on four selected transition metal surfaces [Rh(111), Ru(0001), Ni(111), and Cu(111)] are systematically explored by ab initio calculations. It is found that the core-shell structured C(21), which is a fraction of C(60) possessing three isolated pentagons and C(3v) symmetry, is a very stable magic cluster on all these metal surfaces. Comparison with experimental scanning tunneling microscopy images, dI/dV curves, and cluster heights proves that C(21) is the experimentally observed dominating C precursor in graphene chemical vapor deposition (CVD) growth. The exceptional stability of the C(21) cluster is attributed to its high symmetry, core-shell geometry, and strong binding between edge C atoms and the metal surfaces. Besides, the high barrier of two C(21) clusters' dimerization explains its temperature-dependent behavior in graphene CVD growth.