Chemoselective Hydrogenation of Nitroaromatics at the Nanoscale Iron(III)–OH–Platinum Interface

Abstract

Catalytic hydrogenation of nitroaromatics is an environment‐benign strategy to produce industrially important aniline intermediates. Herein, we report that Fe(OH)x deposition on Pt nanocrystals to give Fe(OH)x/Pt, enables the selective hydrogenation of nitro groups into amino groups without hydrogenating other functional groups on the aromatic ring. The unique catalytic behavior is identified to be associated with the FeIII‐OH‐Pt interfaces. While H2 activation occurs on exposed Pt atoms to ensure the high activity, the high selectivity towards the production of substituted aniline originates from the FeIII‐OH‐Pt interfaces. In situ IR, X‐ray photoelectron spectroscopy (XPS), and isotope effect studies reveal that the Fe3+/Fe2+ redox couple facilitates the hydrodeoxygenation of the ‐NO2 group during hydrogenation catalysis. Benefitting from FeIII‐OH‐Pt interfaces, the Fe(OH)x/Pt catalysts exhibit high catalytic performance towards a broad range of substituted nitroarenes.

Tuning the Electronic and Steric Interaction at the Atomic Interface for Enhanced Oxygen Evolution

“…12,13 As in the case of depositing Fe(OH) x onto Pt nanocrystals, the coordinatively unsaturated Fe 2+ −OH−Pt interface was prone to reduce N−O bonds rather than C C bonds, leading to highly selective hydrogenation of nitroaromatics. 14 In recent years, the emergence of single-atom catalysts has expanded mechanistic research on heterogeneous catalysts to an atomic level with a tunable coordination environment around the metal centers. 15−19 However, it remains elusive whether the concept and regulation mechanism of conventional one-dimensional interfaces apply to zero-dimensional single atoms.…”

“…Heterogeneous catalysis takes place on the two-dimensional surface or one-dimensional interface of catalysts. − Created by hybridizing two components with different physical and chemical properties, the interfaces govern the binding of reactants for the optimized catalytic performance by virtue of their electronic distributions and atomic configurations. − The electron exchange between these components modulates the localized electronic structure at the interface to tune the adsorption strength of reactants. − For instance, a defect-free Au–TiO 2 interface allows for electron transfer from the TiO 2 support to Au nanoparticles, which was further migrated to activate adsorbed O 2 on the interfacial perimeters . In addition, the interfacial atomic arrangements probably provide multiple sites to synergistically alter the adsorption structure of reaction intermediates, leading to the optimized reaction pathways. , As in the case of depositing Fe­(OH) x onto Pt nanocrystals, the coordinatively unsaturated Fe 2+ –OH–Pt interface was prone to reduce N–O bonds rather than CC bonds, leading to highly selective hydrogenation of nitroaromatics . In recent years, the emergence of single-atom catalysts has expanded mechanistic research on heterogeneous catalysts to an atomic level with a tunable coordination environment around the metal centers. − However, it remains elusive whether the concept and regulation mechanism of conventional one-dimensional interfaces apply to zero-dimensional single atoms.…”

Hydrogen Interaction with Oxide Supports in the Presence and Absence of Platinum

“…For iron oxide, ceria, and titania, the major findings of this work are schematically depicted in Scheme , which highlights the diverse nature of hydrogen interaction with platinum–metal oxide catalysts . Iron oxide has the lowest uptake temperature for hydrogen in the presence of platinum via spillover and is an excellent hydrogenation catalyst for aromatic nitrocompounds . However, easily induced phase transition may be an unwanted effect in catalysis since it may corrupt the catalyst’s lifetime.…”

“… 13 Iron oxide has the lowest uptake temperature for hydrogen in the presence of platinum via spillover and is an excellent hydrogenation catalyst for aromatic nitrocompounds. 45 However, easily induced phase transition may be an unwanted effect in catalysis since it may corrupt the catalyst’s lifetime. Furthermore, this low reduction temperature explains the origin of the very often reported encapsulation of the noble metal with iron oxide during reduction or reaction, the so-called classical strong metal–support interaction.…”