In Situ Thermal Atomization To Convert Supported Nickel Nanoparticles into Surface‐Bound Nickel Single‐Atom Catalysts

Abstract

The arrangement of the active sites on the surface of ac atalysts can reduce the problem of mass transfer and enhance the atom economy.H erein, supported Ni metal nanoparticles can be transformed to thermal stable Ni single atoms,mostly located on the surface of the support. Assisted by N-doped carbon with abundant defects,t his synthetic process not only transform the nanoparticles to single atoms,b ut also creates numerous pores to facilitate the contact of dissolved CO 2 and single Ni sites.The proposed mechanism is that the Ni nanoparticles could break surface CÀCb onds drill into the carbon matrix, leaving pores on the surface.W hen Ni nanoparticles are exposed to N-doped carbon, the strong coordination splits Ni atoms from Ni NPs.The Ni atoms are stabilized within the surface of carbon substrate.T he continuous loss of atomic Ni species from the NPs would finally result in atomization of Ni NPs.C O 2 electroreduction testing shows that the surface enriched with Ni single atoms delivers better performance than supported Ni NPs and other similar catalysts.Owing to the massive CO 2 production from consuming the carbon-based fuels,c limatic problems have been triggered, especially global warming and glaciers melting. [1] It is urgent to search for the efficient ways to decrease the CO 2 accumulation in air.R ecently,e lectroreduction of CO 2 has been regarded as ap romising approach to decrease CO 2 as well as convert it into the other useful raw materials,such as CO,C H 4 ,C 2 H 4 ,H COOH. [2] Thei deal CO 2 electroreduction heterogeneous catalyst should contain highly dispersed active species on the support and sufficient accessible surface to prevent the problem of the mass transfer.H ence,aporous support is adopted, which could not only stabilize the reactive sites but also guarantee the fast adsorption of reactants and desorption of products.R ecently,s ingle-atom catalysts have drawn much attention for the electroreduction of CO 2 owing to their electrochemical performances and atom economy. [3] However,t he main problem is that most of the synthetic methods for single-atoms catalysts are based on the bottomup strategy,i nw hich the metal ions are adsorbed on the defect-containing matrix and then reduced to form single atoms in the whole support. [4] Based on this bottom-up method, the porous supports are incapable of confining most of the atomic metal species to the surface as they cannot prevent the migration of metal within the support matrix. This will result in the homogeneous distribution of single metal sites within the entire matrix rather than on the surface,a nd results in of mass transportation issues and deactivation of the catalytic process.To tackle this challenge,w ed escribe an ovel top-down strategy,during which the Ni nanoparticles (NPs) distributed on the surface of defect-containing N-doped carbon (NC) supports can be transformed into Ni single atoms on the surface by at hermal diffusion mechanism, which is quite different to the previous reports through vaporizing the nanoparticles ...

Effects of the Carbon Support Doping with Nitrogen for the Hydrogen Production from Formic Acid over Ni Catalysts

“…Nickel is able to form single Ni atoms (cations) on the surface of nitrogen-doped carbon [16], which could be the active sites for some hydrogenation [17] and CO 2 electroreduction [18][19][20][21] reactions. It is not known whether these Ni species can be active in the formic acid decomposition reaction.…”

Supported Single Atoms as New Class of Catalysts for Electrochemical Reduction of Carbon Dioxide

“…Most recently, we synthesized Ni SACs that anchored on the edges of a porous carbon structures with and without the N dopant, and found that the Ni SACs without N doping show a very small current for CO 2 RR with selectivity less than 10%, while the Ni SACs coordinated with N show a high current density for CO 2 RR with selectivity over 90% . Yang et al found that the strong coordination of Ni with N could split Ni atoms from Ni NPs and the continuous loss of atomic Ni species from the NPs would finally result in atomization of Ni NPs . These findings further demonstrate that the atomically dispersed Ni atoms are most likely coordinated with N rather than C. The results so far show that the Ni atoms that coordinated with N could be the major active center for CO 2 RR.…”

Designing the future atomic electrocatalyst for efficient energy systems

“…The variable metal nodes and organic linkers enable the post‐modification and more possible synthetic routes. The ZIF‐8 MOF is a frequent choice as the SAC precursor due to the above reasons, and the SACs derived from it have been reported to exhibit excellent CO 2 RR performance 113,142,149‐154 …”