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Mechanochemistry emerged as an effective tool for the synthesis of nanomaterials, with potentially scalable prospects. This contribution aims to provide an overview of the most recent potential of mechanochemical routes in designing advanced nanomaterials including zeolites, metal oxides, and mixed metal oxides because of their catalytic applications. In the present review, the role of mechanochemistry in material design, the effect of mechanical energy on the surface area/surface properties, and recent trends in the field are discussed. A comparison of catalytic activities in selected cases for the materials prepared using conventional vs mechanochemical route has been provided.

The present work demonstrates the effect of temperature-dependent surface modification (SM) treatment and its influence in broadening the catalysis regime with Pd–TiO2 catalysts prepared by various methods. Due to SM induced changes, a shift in the onset of CO oxidation activity as well as broadening of the oxidation catalysis regime by 30 to 65 K to lower temperatures is observed compared to the temperature required for virgin counterparts. SM carried out at 523 K for PdPhoto–TiO2 exhibits the lowest onset (10% CO2 production – T10) and T100 for CO oxidation at 360 and 392 K, respectively, while its virgin counterpart shows T10 and T100 at 393 and 433 K, respectively. The SMd Pd–TiO2 catalysts were investigated using X-ray photoelectron spectroscopy (XPS), ultra-violet photoelectron spectroscopy (UPS) and atomic force microscopy (AFM). It is observed that diffusion of atomic oxygen into Pd-subsurfaces leads to SM and changes the nature of the surface significantly. These changes are demonstrated by work function (φ), surface potential, catalytic activity, and correlation among them. UPS results demonstrate the maximum increase in φ by 0.5 eV for PdPhoto–TiO2 after SM, compared to all other catalysts. XPS study shows a moderate to severe change in the oxidation states of Pd due to atomic oxygen diffusion into the subsurface layers of Pd. Kelvin probe force microscopy (KPFM) study also reveals corroborating evidence that the surface potential increases linearly with increasing temperature deployed for SM up to 523 K, followed by a marginal decrease at 573 K. The φ measured by KPFM and UPS shows a similar trend and correlates well with the changes in catalysis observed. Our results indicate that there is a strong correlation between surface physical and chemical properties, and φ changes could be considered as a global marker for chemical reactivity. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, we explored novel CeZrO4−δ as a catalyst for Knoevenagel condensation of aldehydes with reactive methylene compounds like malononitrile and ethylcyanoacetate. For the present study, ceria, zirconia and CeZrO4−δ were prepared by gel combustion method and well characterized using XRD, SEM, EDX, BET and TPD analyses, etc. A wide range of aldehydes were effectively condensed over novel CeZrO4−δ with reactive methylene compounds with high yields. In addition, the CeZrO4−δ was effectively reused for five consecutive cycles without significant loss in its activity. To the best of our knowledge, this is the first liquid-phase application of pure CeZrO4−δ.Graphical abstract: [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline phase pure CeCrO3 was synthesized by a two step preparation method. The prepared material was characterized by techniques such as X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HR-TEM), EDX and SEM analysis. The catalytic activity of CeCrO3 was investigated for the oxidation of benzylic alcohols to the corresponding carbonyls using TBHP as oxidant. Oxidation of several structurally diverse primary and secondary benzylic alcohols were studied with the CeCrO3/TBHP catalytic system. The catalyst exhibited significant catalytic activity and selectivity in most of the cases. [Copyright &y& Elsevier]