Multichromophoric Triad and g-C3N4 Composite as Efficient Heterogeneous Photocatalyst for Oxidative Amidation of Aldehydes.

In this work, we have synthesized a multichromophoric light-harvesting antenna, namely, triad, consisting of naphthalene monoimide (NMI) and perylene monoimide (PMI) chromophores. Triad was adsorbed onto polymeric graphitic carbon nitride (g-C3N4) to form triad/g-C3N4 composite, utilized as a photocatalyst for oxidative amidation reaction. This composite photocatalyst demonstrated enhanced photocatalytic activity for the conversion of a variety of aldehydes to amides, leading up to 82% product yield compared to only g-C3N4 or only triad as photocatalysts.

Naphthalene Monoanhydride and Perylene Composites for Efficient Photocatalytic Hydrogen Evolution and Metal-Free Heterogeneous Oxidative Amidation.

This study explores the synthesis of two visible light active organic chromophore-based composites using naphthalene monoanhydride () and 1,7-dibromoperylene monoanhydride diester (). These chromophores feature favorable optical and electronic properties and polyaromatic skeletons with anhydride functionalities that facilitate π-π interactions between the chromophore and polymeric carbon nitride () or covalent connections of chromophores with NH groups of . Accordingly, heterogeneous chromophore- composite photocatalysts namely, and were prepared by adopting calcination (c) and composites and were prepared by physical adsorption (a) methods.

A surface reconstruction route for increasingly improved photocatalytic HO production using SrBiTaOCl.

Photocatalytic hydrogen peroxide (HO) generation is attractive for the chemical industry and energy production. However, photocatalysts generally deteriorate significantly during use to limit their application. Here we present highly active SrBiTaOCl single-crystal nanoplates for conversion of O to HO using ambient air with a production rate of ∼3 mmol h g (maximum 17.

Waste Polyethylene-Derived Carbon Dots: Administration of Metal-Free Oxidizing Agents for Tunable Properties and Photocatalytic Hyperactivity.

The possibility of converting waste plastics into carbon dots (CDs) with 100% efficiencies using KMnO has emerged as a significant discovery in mitigating plastic pollution and upcycling. However, the lack of tunability of their properties, viz. aerial O harvesting, light-induced autophagy, and photoactivity using air as a free oxidant, has remained a bottleneck.

Stimuli-Responsive Control over Self-Assembled Nanostructures in Sequence-Specific Functional Block Copolymers.

The precise sequence of a protein's primary structure is essential in determining its folding pathways. To emulate the complexity of these biomolecules, functional block copolymers consisting of segmented triblocks with distinct functionalities positioned in a sequence-specific manner are designed to control the polymer chain compaction. Triblock polymers and and random diblock copolymer consist of a hydrophilic poly(ethylene oxide) (PEO) block and a hydrophobic block with coumarin () and ferrocene () moieties that are grafted in a sequence-specific or random manner onto the hydrophilic block.

Mild chemistry synthesis of ultrathin BiOS nanosheets exhibiting 2D-ferroelectricity at room temperature.

Modern technology demands miniaturization of electronic components to build small, light, and portable devices. Hence, discovery and synthesis of new non-toxic, low cost, ultra-thin ferroelectric materials having potential applications in various electronic and optoelectronic devices are of paramount importance. However, achieving room-temperature ferroelectricity in two dimensional (2D) ultra-thin systems remains a major challenge as conventional three-dimensional ferroelectric materials lose their ferroelectricity when the thickness is brought down below a critical value owing to the depolarization field.

Extending conducting channels in Fe-N-C by interfacial growth of CNTs with minimal metal loss for efficient ORR electrocatalysis.

Achieving a high electrocatalytic performance using a completely metal-free electrocatalyst, preferably based on only carbonaceous materials, remains a challenge. Alternatively, an efficient composite of a carbon nanostructure and a non-noble metal with minimum dependence on a metal holds immense potential. Although single-atom catalysis brings superior performance, its complex synthetic strategy limits its large-scale implementation.

Universal Piezo-Photocatalytic Wastewater Treatment on Realistic Pollutant Feedstocks by BiTaOCl: Origin of High Efficiency and Adjustable Synergy.

Clean water is a fundamental human right but millions struggle for it daily. Herein, we demonstrate a new piezo-photocatalyst with immense structural diversity for universal wastewater decontamination. Single-crystalline BiTaOCl nanoplates with exposed piezoelectric facets exhibit visible-light response, piezoelectric behavior with coercive voltages of ±5 V yielding 0.

BiTaOCl as a New Class of Layered Perovskite Oxyhalide Materials for Piezopotential Driven Efficient Seawater Splitting.

Piezocatalytic water splitting is an emerging approach to generate "green hydrogen" that can address several drawbacks of photocatalytic and electrocatalytic approaches. However, existing piezocatalysts are few and with minimal structural flexibility for engineering properties. Moreover, the scope of utilizing unprocessed water is yet unknown and may widely differ from competing techniques due to the constantly varying nature of surface potential.

Role of interfacial contact between 2D materials and preselected nanostructures in the degradation of toxic dyes: Multifunctional facets of graphene.

Designing intimate interfacial contact between nanostructures and two-dimensional (2D) materials is highly desirable to influence the movement of generated charge carriers. Nanostructured zinc oxide (ZnO) is a fascinating material with unique optical and electrical properties. 2D reduced graphene oxide (rGO) exhibits semiconductor behaviour with tunable catalytic activity and excellent biocompatibility.

Confinement Matters: Stabilization of CdS Nanoparticles inside a Postmodified MOF toward Photocatalytic Hydrogen Evolution.

Insights into developing innovative routes for the stabilization of photogenerated charge-separated states by suppressing charge recombination in photocatalysts is a topic of immense importance. Herein, we report the synthesis of a metal-organic framework (MOF)-based composite where CdS nanoparticles (NPs) are confined inside the nanosized pores of Zr-based MOF-808, namely, CdS@MOF-808. Anchoring l-cysteine into the nanospace of MOF-808 via postsynthetic ligand exchange allows the capture of Cd ions from their aqueous solution, which are further utilized for in situ growth of CdS NPs inside the nanosized MOF pores.

Light-Induced Hypoxia in Carbon Quantum Dots and Ultrahigh Photocatalytic Efficiency.

Carbon quantum dots (CQDs) represent a class of carbon materials exhibiting photoresponse and many potential applications. Here, we present a unique property that dissolved CQDs capture large amounts of molecular oxygen from the air, the quantity of which can be controlled by light irradiation. The O content can be varied between a remarkable 1 wt % of the CQDs in the dark to nearly half of it under illumination, in a reversible manner.

Synthesis, characterization, and photocatalytic activity of ZnO nanoparticles using water extract of waste coconut husk.

The present work reports the use of natural alkaline extract from coconut husk ash as a precipitating agent for metal oxide nanoparticles synthesis. The abundance of KO and KCO in it makes the extract highly basic and could be the alternative source of basic media in the laboratory. In this study, highly photoactive zinc oxide nanoparticles have been synthesized using water extract of waste coconut husk ash in a green approach which is considered as replacement of homogeneous base like NaOH and KOH.

Ultrathin Twisty PdNi Alloy Nanowires as Highly Active ORR Electrocatalysts Exhibiting Morphology-Induced Durability over 200 K Cycles.

Even though the anion exchange membrane fuel cells have many advantages, the stability of their electrocatalysts for oxygen reduction reaction (ORR) has remained remarkably poor. We report here on the ultrathin twisty PdNi-alloy nanowires (NWs) exhibiting a very low reaction overpotential with an  ∼ 0.95 V versus RHE in alkaline media maintained over 200 K cycles, the highest ever recorded for an electrocatalyst.

Dimension switchable auto-fluorescent peptide-based 1D and 2D nano-assemblies and their self-influence on intracellular fate and drug delivery.

The production of dynamic, environment-responsive shape-tunable biomaterials marks a significant step forward in the construction of synthetic materials that can easily rival their natural counterparts. Significant progress has been made in the self-assembly of bio-materials. However, the self-assembly of a peptide into morphologically distinct auto-fluorescent nanostructures, without the incorporation of any external moiety is still in its infancy.

Defect-rich, negatively-charged SnS nanosheets for efficient photocatalytic Cr(VI) reduction and organic dye adsorption in water.

Nanostructures of layered materials have gained increasing attention in photocatalytic and water-treatment processes. Herein, we report on sub-30 nm SnS nanosheets (NSs) which can perform photocatalytic reduction of Cr(VI) to Cr(III) quite efficiently on one hand, while removes large quantities of toxic organic dye molecules by choosing an adsorption mode of operation over photo-degradation on the other hand, unlike most other SnS nanostructures. The NSs have a highly extended crystallinity growing perpendicular to the (001) lattice direction but exhibit poor X-ray diffraction for the 10 l (1 = 1,2,3…) lattice planes.

3D Porous Polymeric-Foam-Supported Pd Nanocrystal as a Highly Efficient and Recyclable Catalyst for Organic Transformations.

The efficient recovery of noble metal nanocrystals used in heterogeneous organic transformations has remained a significant challenge, hindering their use in industry. Herein, highly catalytic Pd nanoparticles (NPs) were first prepared having a yield of >98% by a novel hydrothermal method using PVP as the reducing cum stabilizing agent that exhibited excellent turnover frequencies of ∼38,000 h for Suzuki-Miyaura cross-coupling and ∼1200 h for catalytic reduction of nitroarene compounds in a benign aqueous reaction medium. The Pd NPs were more efficient for cross-coupling of aryl compounds with electron-donating substituents than with electron-donating ones.

'Pre-optimization' of the solvent of nanoparticle synthesis for superior catalytic efficiency: a case study with Pd nanocrystals.

In view of a limited rationale available for designing metal nanocrystals (NCs) to achieve high catalytic activities across various chemical transformations, we offer a new perspective on the optimization of the '' that, to an extent, would help bypass the tedious characterization needs. A systematic improvement in a catalyst is hindered because (i) it relies on size & shape control protocols, surface characterization, understanding molecular transformation mechanisms, and the energetics of the reactant-catalyst interactions, requiring the involvement of different domains experts, and (ii) the insights developed using model reactions may not easily extend to other reactions, although the current studies count on such a hypothesis. In support of (ii), by taking Pd NCs as catalysts and two distinct reaction types, Suzuki coupling and nitroarene reduction, we show to what great extent the reaction rates may vary even for the seemingly similar reactions by using the same NCs.

Facile d-band tailoring in Sub-10 nm Pd cubes by in-situ grafting on nitrogen-doped graphene for highly efficient organic transformations.

We demonstrate for the first time the in-situ synthesis of Pd nanocubes (PdNC) on nitrogen-doped reduced graphene oxide (NRGO) for facile organic transformations wherein the cubic morphology of Pd can only be realized by precision-controlled acid additions in the tune of 0.02 pH variations in the reaction medium. Due to the intimate contact arising from atom-by-atom addition of Pd on NRGO, the composite has exhibited a pronounced catalyst to support charge transfer effect, shift in the d-band center, and lowering of charge-transfer resistance when compared with PdNC-NRGO ex-situ composites prepared by mixing of the preformed components of PdNC and NRGO or PdNCs alone.

Upconversion Nanodevice-Assisted Healthy Molecular Photocorrection.

Mushrooms are rich in ergosterol, a precursor of ergocalciferol, which is a type of vitamin D. The conversion of ergosterol to ergocalciferol takes place in the presence of UV radiation by the cleavage of the "B-ring" in the ergosterol. As the UV radiation cannot penetrate deep into the tissue, only minimal increase occurs in sunlight.

Nanocrystalline AgPO for Sunlight- and Ambient Air-Driven Oxidation of Amines: High Photocatalytic Efficiency and a Facile Catalyst Regeneration Strategy.

Selective oxidation of amines to imines using sunlight as clean and renewable energy source is an important but challenging chemical transformation because of high reactivity of the generated imines and lack of visible light-responsive materials with high conversion rates. In addition, oxygen gas has to be purged in the reaction mixture in order to increase the reaction efficiency which, in itself, is an energy-consuming process. Herein, we report, for the first time, the use of AgPO as an excellent photocatalyst for the oxidative coupling of benzyl amines induced by ambient air in the absence of any external source of molecular oxygen at room temperature.

High and reversible oxygen uptake in carbon dot solutions generated from polyethylene facilitating reactant-enhanced solar light harvesting.

Solar-driven photocatalysis is emerging as a key chemical transformation strategy due to its favourable energy economy. However, in photocatalytic oxidation reactions where molecular oxygen (O2) is a reactant, achieving higher efficiency requires an O2-saturated environment in order to maintain a high oxygen level on the catalyst surface, necessitating an additional energy-consuming step of O2 separation from air. Here we show that in the presence of carbon quantum dots (CQDs), the oxygen content and the ability of O2 to diffuse in water increase significantly.

Synthesis of BiTaO-BiTaOBr composites in ambient air and their high photocatalytic activity upon metal loading.

Herein, we show that composites of BiTaO-BiTaOX (X = Cl, Br), two important Bi- and Ta-based light-responsive phases, can be prepared by high temperature, ambient air treatment of the precursors including easily oxidizable BiOX that retain the halide phases in excess of 60% and exhibit high photocatalytic activity. Furthermore, when these phases were loaded with less than 1% noble metals (Pd, Pt, Ag), nearly complete separation of the photogenerated excitons was observed, leading to a significant enhancement in the photocatalytic activity.

Self-immobilized Pd nanowires as an excellent platform for a continuous flow reactor: efficiency, stability and regeneration.

Despite extensive use of Pd nanocrystals as catalysts, the realization of a Pd-based continuous flow reactor remains a challenge. Difficulties arise due to ill-defined anchoring of the nanocrystals on a substrate and reactivity of the substrate under different reaction conditions. We demonstrate the first metal (Pd) nanowire-based catalytic flow reactor that can be used across different filtration platforms, wherein, reactants flow through a porous network of nanowires (10-1000 nm pore sizes) and the product can be collected as filtrate.

Emerging Materials in Heterogeneous Electrocatalysis Involving Oxygen for Energy Harvesting.

Water-based renewable energy cycle involved in water splitting, fuel cells, and metal-air batteries has been gaining increasing attention for sustainable generation and storage of energy. The major challenges in these technologies arise due to the poor kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reactions (OER), besides the high cost of the catalysts. Attempts to address these issues have led to the development of many novel and inexpensive catalysts as well as newer mechanistic insights, particularly so in the last three-four years when more catalysts have been investigated than ever before.