Hydrogen production from formic acid decomposition in the liquid phase using Pd nanoparticles supported on CNFs with different surface properties

The development of safe and efficient H2 generation/storage materials toward a fuel-cell-based H2 economy as a long-term solution has recently received much attention. Herein we report the development of preformed Pd nanoparticles supported on carbon nanofibers (CNFs) via sol-immobilisation and impregnation techniques as efficient catalysts for the liquid phase decomposition of formic acid to H2. We used CNFs as the preferred choice of support and treated at three different temperatures for the deposition of Pd nanoparticles. They were thoroughly characterised using XRD, XPS, SEM-EDX, TEM, Raman spectroscopy and BET. We observed that the Pd particle size, metal exposure and CNF graphitisation grade play an important role in catalytic performance. We found that Pd/CNFs prepared by the sol-immobilisation method displayed higher catalytic performance than those prepared by the impregnation method, due to the smaller Pd particles and high Pd exposure of the catalysts prepared by the first method. Moreover, we have shown that the best results have been obtained using CNFs with a high graphitisation degree (HHT). DFT studies have been performed to gain insights into the reactivity and decomposition of formic acid along two-reaction pathways on Pd(111), Pd(011) and Pd(001) surfaces

Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons: A Perspective Review

Carbon-based materials show unique chemicophysical properties, and they have been successfully used in many catalytic processes, including the production of chemicals and energy. The introduction of heteroatoms (N, B, P, S) alters the electronic properties, often increasing the reactivity of the surface of nanocarbons. The functional groups on the carbons have been reported to be effective for anchoring metal nanoparticles. Although the interaction between functional groups and metal has been studied by various characterization techniques, theoretical models, and catalytic results, the role and nature of heteroatoms is still an object of discussion. The aim of this review is to elucidate the metal–heteroatoms interaction, providing an overview of the main experimental and theoretical outcomes about heteroatom-mediated metal–support interactions. Selected studies showing the effect of heteroatom–metal interaction in the liquid-phase alcohol oxidation will be also presented