No abstract

From the combination of STM imaging and DFT calculations, we show that both alkali metal and halogens interact with different sites of the target molecules resulting in structural formation in a synergistic way. The elementary metal-organic motifs are connected by Cl in a variety of fashions demonstrating structural diversity.

Transition-metal carbides have sparked unprecedented enthusiasm as high-performance catalysts in recent years. Still, the catalytic properties of copper carbide remain unexplored. By introducing subsurface carbon to Cu(111), a displacement reaction of a proton in a carboxyl acid group with a single Cu atom is demonstrated at the atomic scale and room temperature. Its occurrence is attributed to the C-dopinginduced local charge of surface Cu atoms (up to + 0.30 e/ atom), which accelerates the rate of on-surface deprotonation via reduction of the corresponding energy barrier, thus enabling the instant displacement of a proton with a Cu atom when the molecules adsorb on the surface. This well-defined and robust Cu d+ surface based on subsurface-carbon doping offers a novel catalytic platform for on-surface synthesis.In recent years, transition metal carbides (TMCs), for example, molybdenum carbide, titanium carbide, etc. have shown considerable potential as high-performance catalysts in hydrogen evolution, [1] carbon dioxide reduction, [2] deoxygenation of biomass, [3] and methane dehydroaromatization. [4] TMC catalysts not only accelerate the reaction rate, alter the pathway, but also improve the reaction selectivity, [5] and even enable reactions that cannot be triggered by conventional metal catalysts. [6] However, the reported work has substantially focused on the fabrication of TMCs and their catalytic performance based on spectroscopic measurements, whilst intuitive studies of catalytic reactions on TMCs at the atomic/ molecular scales are rather scarce.Copper (Cu), as one of the most classical catalysts, has been applied extensively in selective oxidation, [7] coupling reaction, [8] carbon dioxide reduction, [9] etc. It has been proposed that charge localization on Cu (Cu d+ ) achieved by doping nonmetals (e.g. oxygen, [9b, 10] boron, [11] nitrogen [12] ) can significantly boost the catalytic activities of the parent metal and modify the reaction process, for example, enhance the Faradaic efficiency for C 2 hydrocarbons in carbon dioxide reduction. [11a] Since the extrinsic species on top of a Cu surface have a high probability to be removed or modified upon chemical reactions, which results in the reduction of Cu d+ to Cu 0 , [9b, 13] subsurface doping is believed to be advantageous for long-term, stable catalytic performance. [10b, 11a] In regard to compatibility with Cu, carbon (C), one of the typical minorities in natural Cu bulk, certainly holds advantages over other elements. [14] However, local charge of Cu surface induced by C-doping and the catalytic properties of Cu carbide or C-doped Cu are still unexplored.Herein, we report a locally charged Cu surface layer induced by subsurface C (C-Cu d+ ) and its catalytic application for an on-surface displacement reaction (Scheme 1). Applying 3,5-bis(carboxyl acid)-phenyl-3-maleimide (C 12 H 7 NO 6 , denoted as BCPM) on C-Cu d+ , efficient substitution of the proton in each carboxylic acid (CA) group of BCPM by a single Cu atom is demonstrated at ...