Production of anilines--key intermediates for the fine chemical, agrochemical, and pharmaceutical industries--relies on precious metal catalysts that selectively hydrogenate aryl nitro groups in the presence of other easily reducible functionalities. Herein, we report convenient and stable iron oxide (Fe2O3)-based catalysts as a more earth-abundant alternative for this transformation. Pyrolysis of iron-phenanthroline complexes on carbon furnishes a unique structure in which the active Fe2O3 particles are surrounded by a nitrogen-doped carbon layer. Highly selective hydrogenation of numerous structurally diverse nitroarenes (more than 80 examples) proceeded in good to excellent yield under industrially viable conditions.

Molecularly well-defined homogeneous catalysts are known for a wide variety of chemical transformations. The effect of small changes in molecular structure can be studied in detail and used to optimize many processes. However, many industrial processes require heterogeneous catalysts because of their stability, ease of separation and recyclability, but these are more difficult to control on a molecular level. Here, we describe the conversion of homogeneous cobalt complexes into heterogeneous cobalt oxide catalysts via immobilization and pyrolysis on activated carbon. The catalysts thus produced are useful for the industrially important reduction of nitroarenes to anilines. The ligand indirectly controls the selectivity and activity of the recyclable catalyst and catalyst optimization can be performed at the level of the solution-phase precursor before conversion into the active heterogeneous catalyst.

Propane dehydrogenation (PDH) to propene is an important alternative to oil-based cracking processes, to produce this industrially important platform chemical1,2. The commercial PDH technologies utilizing Cr-containing (refs. 3,4) or Pt-containing (refs. 5–8) catalysts suffer from the toxicity of Cr(vi) compounds or the need to use ecologically harmful chlorine for catalyst regeneration9. Here, we introduce a method for preparation of environmentally compatible supported catalysts based on commercial ZnO. This metal oxide and a support (zeolite or common metal oxide) are used as a physical mixture or in the form of two layers with ZnO as the upstream layer. Supported ZnOx species are in situ formed through a reaction of support OH groups with Zn atoms generated from ZnO upon reductive treatment above 550 °C. Using different complementary characterization methods, we identify the decisive role of defective OH groups for the formation of active ZnOx species. For benchmarking purposes, the developed ZnO–silicalite-1 and an analogue of commercial K–CrOx/Al2O3 were tested in the same setup under industrially relevant conditions at close propane conversion over about 400 h on propane stream. The developed catalyst reveals about three times higher propene productivity at similar propene selectivity.

Covalent organic frameworks (COFs) have emerged as an important class of organic semiconductors and photocatalysts for the hydrogen evolution reaction (HER)from water.T oo ptimize their photocatalytic activity,t ypically the organic moieties constituting the frameworks are considered and the most suitable combinations of them are searched for. However,t he effect of the covalent linkage between these moieties on the photocatalytic performance has rarely been studied. Herein, we demonstrate that donor-acceptor (D-A) type imine-linked COFs can produce hydrogen with ar ate as high as 20.7 mmol g À1 h À1 under visible light irradiation, upon protonation of their imine linkages.Asignificant red-shift in light absorbance,largely improved charge separation efficiency,a nd an increase in hydrophilicity triggered by protonation of the Schiff-base moieties in the imine-linked COFs,a re responsible for the improved photocatalytic performance.

Photocatalytic ozonation of wastewater pollutants by sunlight is a highly attractive technology close to real application. Understanding this process on the atomic scale and under realistic working conditions is challenging but vital for the rational design of catalysts and photocatalytic decontamination systems. Here we study two highly active C 3 N 4 photocatalysts (bulk C 3 N 4 and a nanosheet-structured C 3 N 4 ) under simultaneous visible-light irradiation and O 3 bubbling in water by in situ EPR spectroscopy coupled with an online spintrapping technique. The photoexcitation of electrons to the conduction band (CB-e − ), their further trapping by dissolved O 2 and O 3 , and the evolution of reactive oxygen species (ROS) have been semiquantitatively visualized. A dual role of O 3 in boosting the CB-e − to • OH conversion is confirmed: (i) an inlet 2.1 mol % O 3 /O 2 gas mixture can trap about 2−3 times more CB-e − upon aqueous C 3 N 4 suspension than pure O 2 and further produce • OH by a robust • O 3 − -mediated one-electron-reduction pathway (O 3 → • O 3 − → HO 3 • → • OH); (ii) O 3 can readily take CB-e − back from • O 2 − to form • O 3 − , thus blocking the inefficient H 2 O 2 -mediated three-electron-reduction route (O 2 → • O 2 − → HO 2 • → H 2 O 2 → • OH) but further strengthening the • O 3 − -mediated pathway. In the presence of 2.1 mol % O 3 /O 2 , the • OH yield increases by 17 and 5 times, and consequently, the mineralization rate constant of oxalic acid increases by 84 and 41 times over bulk C 3 N 4 and NS C 3 N 4 , respectively. This work presents an attractive opportunity to boost the yield of ROS species ( • OH) for water purification by visible-light-driven photocatalysis and provides a powerful tool to monitor complex photocatalytic reactions under practical conditions.