Coordination-induced amidated modified polyacrylonitrile loaded ultrafine palladium nanoparticles for thermocatalytic hydrogen evolution

The formation mechanism of ultrafine Pd nanoparticles (Pd NPs) was elucidated using the coordination-induced strategy within a multiple-groups system. As a result, loading amidated polyacrylonitrile (PAN) onto ultrafine Pd NPs led to a substantial enhancement in hydrogen production from formic acid when compared to the larger-sized Pd@PAN. [Display omitted] •Ultrafine Pd NPs are prepared by a stronger coordination.•The activity increases from 113 h−1 to 1309 h−1 at 323 K for Pd@PAN and Pd@APAN.•Pd-imine and Pd-secondary amine construct favorable catalysis microenvironments.•Multiple-groups modification opens a novel pathway on efficient FAD catalysts. A promising approach for powering hydrogen fuel cells (HFCs) involves the in-situ production of hydrogen from formic acid decomposition, with Pd-based catalysts recognized as effective for formic acid dehydrogenation. However, the immobilization of ultrafine palladium nanoparticles (Pd NPs) on catalytic supports presents a challenge and necessitates further investigation into their formation mechanism. We propose a coordination-induced strategy to understand the behavior of ultrafine Pd NPs formation based on multi-functional groups. To establish the structure–activity relationship for tunable Pd microenvironment and catalytic performance, we synthesized various polyacrylonitrile (PAN) carriers through hydrolysis and amidation modification. Molecular dynamics simulations confirmed that a stronger coordination-induced microenvironment facilitates the dispersion of Pd2+, suppressing aggregation and enhancing Pd loading. Our experimental results and density functional theory (DFT) calculations demonstrated that the catalytic activity of Pd@APAN(15_1%) with ultrafine Pd NPs (1.5 nm) exhibits over 10 times higher than that of Pd@PAN NPs with the turnover of frequency climbing from 112.6 h−1 to 1309.4 h−1 at 323 K. And Pd-imine and Pd-secondary amine moieties were verified to contribute to the creation of a favorable catalysis microenvironment. This study provides new insights into the design of modified supports with various groups to load well-dispersed and ultrafine Pd for highly efficient catalysts based on a coordination-induced strategy.