PdCoNi Alloy Catalysts Supported On Nitrogen-doped Carbon For Hydrogen Production From Formic Acid Decomposition

In order to further promote practical applications of formic acid(HCOOH,FA)as the hydrogen storage material,it is essential to construct favorable catalysts to efficiently decompose FA to hydrogen under ambient conditions.Designing proper heterogeneous catalysts for FA dehydrogenation has very broad prospects,which gradually becomes one of the research focuses in hydrogen storage and production.In this paper,novel nitrogen-doped carbon materials are prepared to support the palladium-based trimetallic alloy.This research aims to develop low-cost and highperformance catalysts for FA decomposition,and explore the relationship between the hierarchical structures and catalytic performance of composite materials.The research results of this paper are as shown below:This part of study focused on Pd-based alloy supported on nitrogen-doped biomass carbon for FA dehydrogenation.The nitrogen-doped microporous carbon nanosheets CNU30 with large specific surface area were prepared by pyrolyzing the mixed powder of chitosan(carbon precursor),urea(nitrogen source)and NaHCO3(porogen)in the nitrogen atmosphere.The Pd0.6Co0.2Ni0.2/CNU30 catalyst was further prepared via a wet chemical reduction method.Nitrogen doping ensured the formation of welldispersed PdCoNi nanoparticles(NPs)on the supports,and the average particle size of NPs was 2.21 nm.The synergistic effect of Pd,Co and Ni induced the formation of electron-rich Pd active sites,which improved the catalytic performance for FA dehydrogenation.Pd0.6Co0.2Ni0.2/CNU30 exhibited outstanding activities for FA dehydrogenation at 25℃,with an initial turnover frequency(TOF)of 874 h-1,which was superior to that of most reported catalysts under the same conditions.Meanwhile,the corresponding hydrogen selectivity and conversion were 100%and 98.0%,respectively.Besides,the recyclability tests showed that the catalyst could be reused at least 3 times without significant deactivation,demonstrating good recycle stability.This part of study focused on Pd-based alloy supported on Schiff base modified carbon nitride for FA dehydrogenation.The Schiff base modified carbon nitride CNSC was synthesized by the calcination of the mixture of urea and terephthalaldehyde,and the Pd0.6Co0.2Ni0.2/CNSC catalyst was prepared via a wet chemical reduction method.It is confirmed that the Schiff base was successfully grafted onto the carbon nitride networks.The average particle size of PdCoNi NPs was 1.70 nm,and the trimetallic PdCoNi alloy was conducive to constructing the electron-rich Pd active sites with outstanding catalytic performance.The transfer of electrons from support to metal demonstrated the strong interaction between PdCoNi NPs and CNSC substrate.The Schiff base groups could facilitate the O-H bond dissociation of FA,thereby promoting the FA decomposition to generate hydrogen.Pd0.6Co0.2Ni0.2/CNSC showed superior catalytic activities for FA dehydrogenation at 25℃,with an initial TOF of 1308 h-1,which outperformed that of most reported catalysts under the same conditions.Meanwhile,the corresponding hydrogen selectivity and conversion were 100%and 99.6%,respectively.Besides,the recyclability tests showed that the catalyst could be reused at least 5 times without significant deactivation,demonstrating great recycle stability.