Co-Based Nanoalloys Coupled With Single-Site Co_sNC For Efficient Catalytic Hydrogen Production

The development of new and high-efficiency ammonia borane（NH₃BH₃,AB）hydrolysis hydrogen production catalysts with excellent performance,low price and no pollution is of great significance for large-scale hydrogen storage and economic development in our country.In recent years,various supported metal catalysts have been developed for the hydrolysis of NH₃BH₃.Among them,precious metals such as ruthenium and platinum have always been one of the efficient catalysts for the hydrolysis of NH₃BH₃ to produce hydrogen,but they are expensive and cannot be used on a large scale.However,non-precious metals with price advantage are relatively low in activity,so it is necessary to design low-cost and high-activity hydrogen production catalysts.In order to reduce the amount of precious metals,transition metal and alloy catalysts were designed,but the commonly used transition metal catalysts have low activity and poor cycle stability.And the metal particles on the surface of the catalyst agglomerate,and the distribution is uneven.The above defects make it urgent to design new functional catalysts for NH₃BH₃ hydrolysis.Metal nanoparticles（NPs）are usually immobilized on various supports with high specific surface area,and good catalytic performance for NH₃BH₃ hydrolysis can be obtained.Nitrogen-doped carbon is considered as an ideal support material because nitrogen atoms can act as electron donors,enhancing catalytic activity and stability.Metal sites and nitrogen species often exhibit synergistic effects that can alter metal electronic states and size distributions,Therefore,cobalt-nitrogen co-doped porous carbon（CosNC）supports provide stronger metal-carrier interaction（EMSI）.The enhanced EMSI effect leads to strong orbital hybridization between the metal nanoparticles and the support surface,which favors electron transfer at the metal-support interface.In this work,we will discuss this issue in detail.Firstly,metal-organic frameworks（MOFs）are used as precursors to prepare nitrogen-doped porous carbon-supported bimetallic alloys,which can effectively inhibit the aggregation of metal particles,improve the hydrogen production performance of NH₃BH₃ hydrolysis,and optimize its reaction kinetics.Metal NPs with reduced size can significantly improve the hydrogen production efficiency due to the increase of accessible active sites.The synthesis process of the catalyst is to first synthesize ZIF-67 at room temperature,after pyrolysis and pickling,the agglomerated metallic Co particles were removed,the porous carbon carrier（CosNC）co-doped with cobalt nitrogen was prepared.Then supported CoRu alloy by impregnation method,and finally made a bimetallic synergistic highefficiency NH₃BH₃ hydrolysis catalyst.CosNC and CoRu alloy act as dual active sites to catalyze,and there is a synergistic effect.CoRu alloy can promote the adsorption and activation of NH₃BH₃,and CosNC can promote the adsorption and activation of water,and they have a strong metal-support interaction,which improves the intrinsic activity of the catalyst,and the hydrogen transition frequency（TOF）is significantly improved.Among them,the TOF of CoRu/CosNC reaches 1068 molH₂·molRu^-1·min^-1,and the apparent activation energy（Ea）is calculated to be about 18.96 kJ·mol^-1,which exceeds most of the cobalt-ruthenium alloy catalysts,And after six cycles of testing,there is no significant performance degradation.The synthesis process of the CoCu/CosNC catalyst is similar to the former.CosNC is also synthesized first,and then the CoCu alloy is supported by the impregnation method,and CoCu/CosNC catalyst is prepared by Ar/H₂ reduction for efficient NH₃BH₃ hydrolysis.The hydrogen transition frequency（TOF）reached 27 molH₂·molCo^-1·min^-1,and the apparent activation energy（Ea）was calculated to be about 22.58 kJ·mol^-1,It also showed excellent cyclic stability.The synergistic promotion between CoCu alloy and CosNC in the bimetallic catalyst effectively lowers the reaction energy barrier and promotes the adsorption and dissociation of NH₃BH₃ and H₂O molecules.This work demonstrates the superiority of a dual-active site catalyst consisting of a combination of bimetallic nanostructures and a co-doped porous carbon structure and provides a new idea for the synthesis of bimetallic catalysts with promising industrial applications in the energy and environmental fields.