Significant Enhancement of Photoactivity in Hybrid TiO₂/g‑C₃N₄ Nanorod Catalysts Modified with Cu–Ni-Based Nanostructures

Light-driven processes such as photocatalytic environmental remediation and photoelectrochemical (PEC) water splitting to produce hydrogen under sunlight are key technologies toward energy sustainability. Despite enormous efforts, a suitable photocatalyst fulfilling all the main requirements such as high photoactivity under visible light, chemical stability, environmental friendliness, and low cost has not been found yet. A promising approach to overcome these limitations is to use hybrid nanostructures showing improved activity and physicochemical properties when compared with single components. Herein, we present a novel photocatalytic nanocomposite system based on titania (TiO₂): titania nanorod wrapped with Ni­(OH)₂ and Cu­(OH)₂ composite carbon nitride (CuNi@g-C₃N₄/TiO₂). This carefully tuned photoanode nanostructure shows almost one order of magnitude higher photocurrent density compared to unsensitized TiO₂ nanorods for PEC water splitting upon solar-light illumination. The heterostructured g-C₃N₄ strongly improves visible absorption of light, separation of electrons and holes, and surface catalysis due to the effect of Cu­(OH)₂ nanoparticles and Ni­(OH)₂ nanosheets, respectively. The improved photoperformance ascribed to the integrative cooperation effect of all the counterparts resulting in a one-dimensional hydrid nanostructured photoanode with improved light absorption, facile charge separation, and efficient surface catalysis toward PEC oxygen evolution

In Situ Generation of Pd–Pt Core–Shell Nanoparticles on Reduced Graphene Oxide (Pd@Pt/rGO) Using Microwaves: Applications in Dehalogenation Reactions and Reduction of Olefins

Core–shell nanocatalysts are a distinctive class of nanomaterials with varied potential applications in view of their unique structure, composition-dependent physicochemical properties, and promising synergism among the individual components. A one-pot microwave (MW)-assisted approach is described to prepare the reduced graphene oxide (rGO)-supported Pd–Pt core–shell nanoparticles, (Pd@Pt/rGO); spherical core–shell nanomaterials (∼95 nm) with Pd core (∼80 nm) and 15 nm Pt shell were nicely distributed on the rGO matrix in view of the choice of reductant and reaction conditions. The well-characterized composite nanomaterials, endowed with synergism among its components and rGO support, served as catalysts in aromatic dehalogenation reactions and for the reduction of olefins with high yield (>98%), excellent selectivity (>98%) and recyclability (up to 5 times); both Pt/rGO and Pd/rGO and even their physical mixtures showed considerably lower conversions (20 and 57%) in dehalogenation of 3-bromoaniline. Similarly, in the reduction of styrene to ethylbenzene, Pd@Pt core–shell nanoparticles (without rGO support) possess considerably lower conversion (60%) compared to Pd@Pt/rGO. The mechanism of dehalogenation reactions with Pd@Pt/rGO catalyst is discussed with the explicit premise that rGO matrix facilitates the adsorption of the reducing agent, thus enhancing its local concentration and expediting the hydrazine decomposition rate. The versatility of the catalyst has been validated via diverse substrate scope for both reduction and dehalogenation reactions

Iron-Oxide-Supported Ultrasmall ZnO Nanoparticles: Applications for Transesterification, Amidation, and O‑Acylation Reactions

An efficient maghemite–ZnO nanocatalyst has been synthesized via a simple coprecipitation method, where ZnO nanoparticles are uniformly decorated on the maghemite core and characterized by XRD, SEM-EDS, ICP-AES, XPS, TEM, HRTEM, and Mössbauer spectroscopy; maghemite nanoparticles are in the typical size range 10–30 nm with ultrasmall (3–5 nm) ZnO nanoparticles. A competent and benign protocol is reported for various organic transformations, namely, transesterification, amidation, and O-acylation reaction in good to excellent yields (75–97%) using magnetically separable and reusable maghemite–ZnO nanocatalyst