Nanoarchitectonics for Abused-Drug Biosensors.

Rapid, accessible, and highly accurate biosensors for the detection of addictive and abused drugs are needed to reduce the adverse personal and societal impacts of addiction. Modern sensors that utilize next-generation technologies, e.g., nanobiotechnology and nanoarchitectonics, have triggered revolutionary progress in the field as they allow accurate detection and tracking of trace levels of major classes of drugs. This paper reviews advances in the field of biosensors for the detection of commonly abused drugs, both prescribed such as codeine and morphine, and illegal narcotics like cocaine.

Hard-templated metal-organic frameworks for advanced applications.

Template-directing strategies for synthesising metal-organic frameworks (MOFs) have brought about new frontiers in materials chemistry due to the possibility of applying control over crystal growth, morphology and secondarily generated pores. In particular, hard templates have resulted in performance breakthroughs in catalysis, secondary ion batteries, supercapacitance, drug delivery and molecular sieving by offering facile routes for maximising the surface areas of shape-directed MOFs. In this tutorial review, a variety of hard templates employed to direct MOFs' growth into superior nano-architectures with enhanced functionalities are discussed. Hard templates discussed here include polymers, silica nanostructures, metal oxides, layered metal hydroxides, noble metals, graphene, zeolites and MOFs themselves. These templates can be divided into three broad categories: sacrificial, semi-sacrificial and non-sacrificial templates. We elaborate on the rationale behind the choice of nanomaterials as hard templates, how hard templates direct the synthesis of MOFs, how sacrificial hard templates can be removed from the final product and what the enhanced functionalities of hard-templated MOFs are. In the case of non-sacrificial hard-templates, synergistic effects arising from the coexistence of the MOF and the hard template will also be reviewed.

Defect engineering of oxide perovskites for catalysis and energy storage: synthesis of chemistry and materials science.

Oxide perovskites have emerged as an important class of materials with important applications in many technological areas, particularly thermocatalysis, electrocatalysis, photocatalysis, and energy storage. However, their implementation faces numerous challenges that are familiar to the chemist and materials scientist. The present work surveys the state-of-the-art by integrating these two viewpoints, focusing on the critical role that defect engineering plays in the design, fabrication, modification, and application of these materials. An extensive review of experimental and simulation studies of the synthesis and performance of oxide perovskites and devices containing these materials is coupled with exposition of the fundamental and applied aspects of defect equilibria. The aim of this approach is to elucidate how these issues can be integrated in order to shed light on the interpretation of the data and what trajectories are suggested by them. This critical examination has revealed a number of areas in which the review can provide a greater understanding. These include considerations of (1) the nature and formation of solid solutions, (2) site filling and stoichiometry, (3) the rationale for the design of defective oxide perovskites, and (4) the complex mechanisms of charge compensation and charge transfer. The review concludes with some proposed strategies to address the challenges in the future development of oxide perovskites and their applications.

Carbamate-Isocyanurate-Bridged Periodic Mesoporous Organosilica for van der Waals CO2 Capture.

We synthesized a new organosiloxane bridge on the basis of an isocyanurate derivative through a simple melt-fusion approach by the reaction of 3-isocyanatopropyltriethoxysilane (IPTES) with 1,3,5-tris(2-hydroxyethyl)-1,3,5-triazinane-2,4,6(1H,3H,5H)-trione (THEIC). The obtained carbamate-isocyanurate-based organosiloxane bridge precursor was used for the preparation of chemo- and thermostable periodic mesoporous organosilica (PMO-THEIC) on condensation with tetrathoxysilane silicon precursor through a soft-template approach. Furthermore, the synthesized PMO-THEIC with unique surface functionality was investigated for CO2 capture. The results show that the PMO-THEIC has higher activity than pure SBA-15 for CO2 capture due to the high affinity of carbamate functionalities embedded within the pore walls toward CO2 molecules. The affinity of organosiloxane bridge for CO2 molecules is mainly facilitated via the van der Waals force with carbamate functional groups rather than the isocyanurate ring, according to the density functional calculations.

Development of Sulfonic-Acid-Functionalized Mesoporous Materials: Synthesis and Catalytic Applications.

Sulfonic acid based mesostructures (SAMs) have been developed in recent years and have important catalytic applications. The primary applications of these materials are in various organic synthesis reactions, such as multicomponent reactions, carbon-carbon bond couplings, protection reactions, and Fries and Beckman rearrangements. This review aims to provide an overview of the recent developments in the field of SAMs with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts.

Metal-Support Interaction in Pt Nanodisk-Carbon Nitride Catalyst: Insight from Theory and Experiment.

Metal-support interaction plays a critical role in determining the eventual catalytic activity of metals loaded on supporting substrates. This interaction can sometimes cause a significant drop in the metallic property of the loaded metal and, hence, a drop in catalytic activity in the reactions, especially in those for which low charge carrier transfer resistance is a necessary parameter. Therefore, there should be a case-by-case experimental or theoretical (or both) in-depth investigation to understand the role of support on each metal. Here, onto a layered porous carbon nitride (g-CN), we grew single crystalline Pt nanodisks (Pt@g-CN) with a lateral average size of 21 nm, followed by various characterisations such as electron microscopy techniques, and the measurement of electrocatalytic activity in the O2 reduction reaction (ORR). We found that intercalating Pt nanodisks in the g-CN interlayers causes an increase in electrocatalytic activity. We investigated the bonding mechanism between carbon support and platinum using density functional theory and applied the d-band theory to understand the catalytic performance. Analysis of Pt's density of states and electronic population across layers sheds light on the catalytic behaviour of Pt nanoparticles, particularly in relation to their thickness and proximity to the g-CN support interface. Our simulation reveals an optimum thickness of ~11 Å, under which the catalytic performance deteriorates.

Feeble Single-Atom Pd Catalysts for H2 Production from Formic Acid.

Single-atom catalysts are thought to be the pinnacle of catalysis. However, for many reactions, their suitability has yet to be unequivocally proven. Here, we demonstrate why single Pd atoms (PdSA) are not catalytically ideal for generating H2 from formic acid as a H2 carrier. We loaded PdSA on three silica substrates, mesoporous silicas functionalized with thiol, amine, and dithiocarbamate functional groups. The Pd catalytic activity on amino-functionalized silica (SiO2-NH2/PdSA) was far higher than that of the thiol-based catalysts (SiO2-S-PdSA and SiO2-NHCS2-PdSA), while the single-atom stability of SiO2-NH2/PdSA against aggregation after the first catalytic cycle was the weakest. In this case, Pd aggregation boosted the reaction yield. Our experiments and calculations demonstrate that PdSA in SiO2-NH2/PdSA loosely binds with amine groups. This leads to a limited charge transfer from Pd to the amine groups and causes high aggregability and catalytic activity. According to the density functional calculations, the loose binding between Pd and N causes most of Pd's 4d electrons in amino-functionalized SiO2 to remain close to the Fermi level and labile for catalysis. However, PdSA chemically binds to the thiol group, resulting in strong hybridization between Pd and S, pulling Pd's 4d states deeper into the conduction band and away from the Fermi level. Consequently, fewer 4d electrons were available for catalysis.

Transforming Cl-Containing Waste Plastics into Carbon Resource for Steelmaking: Theoretical Insight.

The accumulation of waste plastics poses a significant environmental challenge, leading to persistent pollution in terrestrial and aquatic ecosystems. A practical approach to address this issue involves the transformation of postconsumer waste plastics into industrially valuable products. This study focuses on an example of harnessing the carbon content in these polymers for carbon-demanding industrial processes, thereby reducing waste plastics from the environment and alleviating the demand for mined carbon resources. Employing quantum simulations, we examine the viability of polychloroprene as a carburizing agent in the steelmaking process. Our simulations reveal that polychloroprene exhibits excellent carbon diffusivity in molten iron, with a theoretical diffusion coefficient of 8.983 × 10-5cm2 s-1. This value competes favorably with that of metallurgical coke and surpasses the carbon diffusivity of other polymers, such as polycarbonate, polyurethane, and polysulfide. Additionally, our findings demonstrate that the chlorine content in polychloroprene does not permeate into molten iron but instead remains confined to the molten iron and slag interface.

Single-Atom Sn-Loaded Exfoliated Layered Titanate Revealing Enhanced Photocatalytic Activity in Hydrogen Generation.

Green H2 generation through layered materials plays a significant role among a wide variety of materials owing to their high theoretical surface area and distinctive features in (photo)catalysis. Layered titanates (LTs) are a class of these materials, but they suffer from large bandgaps and a layers' stacked form. We first address the successful exfoliation of bulk LT to exfoliated few-layer sheets via long-term dilute HCl treatment at room temperature without any organic exfoliating agents. Then, we demonstrate a substantial photocatalytic activity enhancement through the loading of Sn single atoms on exfoliated LTs (K0.8Ti1.73Li0.27O4). Comprehensive analysis, including time-resolved photoluminescence spectroscopy, revealed the modification of electronic and physical properties of the exfoliated layered titanate for better solar photocatalysis. Upon treating the exfoliated titanate in SnCl2 solution, a Sn single atom was successfully loaded on the exfoliated titanate, which was characterized by spectroscopic and microscopic techniques, including aberration-corrected transmission electron microscopy. The exfoliated titanate with an optimal Sn loading exhibited a good photocatalytic H2 evolution from water containing methanol and from ammonia borane (AB) dehydrogenation, which was not only enhanced from the pristine LT, but higher than conventional TiO2-based photocatalysts like Au-loaded P25.

Composition-driven morphological evolution of BaTiO3 nanowires for efficient piezocatalytic hydrogen production.

Hydrogen production from water by piezocatalysis is very attractive owing to its high energy efficiency and novelty. BaTiO3, a highly piezoelectric material, is particularly suitable for this application due to its high piezoelectric potential, non-toxic nature, and physicochemical stability. Owing to the critical role of morphology on properties, one-dimensional (1D) materials are expected to exhibit superior water-splitting performance and thus there is a need to optimise the processing conditions to develop outstanding piezocatalysts. In the present work, piezoelectric BaTiO3 nanowires (NWs) were hydrothermally synthesised with precursor Ba:Ti molar ratios of 1:1, 2:1, and 4:1. The morphology, defect chemistry, and hydrogen evolution reaction (HER) efficiency of the as-synthesised BaTiO3 NWs were systematically investigated. The results showed that the morphological features, aspect ratio, structural stability and defect contents of the 1D morphologies collectively have a significant impact on the HER efficiency. The morphological evolution mechanism of the 1D structures were described in terms of ion exchange and dissolution-growth processes of template-grown BaTiO3 NWs for different Ba:Ti molar ratios. Notably, the BaTiO3 NWs synthesised with Ba:Ti molar ratio of 2:1 displayed high crystallinity, good defect concentrations, and good structural integrity under ultrasonication, resulting in an outstanding HER efficiency of 149.24 µmol h-1g-1 which is the highest obtained for nanowire morphologies. These results highlight the importance of synthesis conditions for BaTiO3 NWs for generating excellent piezocatalytic water splitting performance. Additionally, post-ultrasonication tested BaTiO3 NWs demonstrated unexpected photocatalytic activity, with the BTO-1 sample (1:1 Ba:Ti) exhibiting 56% photodegradation of RhB in 2 h of UV irradiation.

Ultrasonically-assisted synthesis of CeO2 within WS2 interlayers forming type II heterojunction for a VOC photocatalytic oxidation.

Here, we investigate the band structure, density of states, photocatalytic activity, and heterojunction mechanism of WS2 with CeO2 (CeO2@WS2) as a photoactive heterostructure. In this heterostructure, CeO2's growth within WS2 layers is achieved through ultrasonicating WS2 and intercalating CeO2's precursor within the WS2 interlayers, followed by hydrothermal treatment. Through a set of density functional calculations, we demonstrate that CeO2 and WS2 form an interface through a covalent bonding that can be highly stable. The electrochemical impedance spectroscopy (EIS) found that the CeO2@WS2 heterostructure exhibits a remarkably higher conductivity (22.23 mS cm-2) compared to either WS2 and CeO2, assignable to the interface in CeO2@WS2. Furthermore, in a physically mixed CeO2-WS2 where the interaction between particles is noncovalent, the resistance was significantly higher (0.67 mS cm-2), confirming that the heterostructure in the interface is covalently bonded. In addition, Mott-Schottky and the bandgap measurements through Tauc plots demonstrate that the heterojunction in CeO2 and WS2 is type II. Eventually, the CeO2@WS2 heterostructure indicated 446.7 µmol g -1 CO2 generation from photocatalytic oxidation of a volatile organic compound (VOC), formic acid, compared to WS2 and CeO2 alone.

Templated Synthesis of Exfoliated Porous Carbon with Dominant Graphitic Nitrogen.

We present here a new approach for the synthesis of nitrogen-doped porous graphitic carbon (g-NC) with a stoichiometry of C6.3H3.6N1.0O1.2, using layered silicate as a hard sacrificial template. Autogenous exfoliation is achieved due to the heterostacking of 2D silicate and nitrogen-doped carbon layers. Micro- and meso-porosity is induced by melamine and cetyltrimethylammonium (C16TMA). Our density functional calculations and X-ray photoelectron spectroscopy (XPS) observations confirm that the most dominant nitrogen configuration in g-CN is graphitic, while pyridinic and pyrrolic nitrogens are thermodynamically less favored. Our large-scale lattice dynamics calculations show that surface termination with H and OH groups at pores accounts for the observed H and O in the composition of the synthesized g-NC. We further evaluate the electrocatalytic and the supercapacitance activities of g-NC. Interestingly, this material exhibits a specific capacitance of ca. 202 F g-1 at 1 A g-1, retaining 90% of its initial capacitance after 10,000 cycles.

In Situ Formation of Copper Phosphate on Hydroxyapatite for Wastewater Treatment.

Here, we control the surface activity of hydroxyapatite (HAp) in wastewater treatment which undergoes peroxodisulfate (PDS) activation. Loading the catalytically active Cu species on HAp forms a copper phosphate in the outer layer of HAp. This modification turns a low active HAp into a high catalytically active catalyst in the dye degradation process. The optimal operational conditions were established to be [Cu-THAp]0 = 1 g/L, [RhB]0 = 20 mg/L, [PDS]0 = 7.5 mmol/L, and pH = 3. The experiments indicate that the simultaneous presence of Cu-THAp and PDS synergistically affect the degradation process. Additionally, chemical and structural characterizations proved the stability and effectiveness of Cu-THAp. Therefore, this work introduces a simple approach to water purification through green and sustainable HAp-based materials.

Stability Trends in Mono-Metallic 3d Layered Double Hydroxides.

Layered double hydroxides (LDHs) constitute a unique group of 2D materials that can deliver exceptional catalytic, optical, and electronic performance. However, they usually suffer from low stability compared to their oxide counterparts. Using density functional calculations, we quantitatively demonstrate the crucial impact of the intercalants (i.e., water, lactate, and carbonate) on the stability of a series of common LDHs based on Mn, Fe, and Co. We found that intercalation with the singly charged lactate results in higher stability in all these LDH compounds, compared to neutral water and doubly charged carbonate. Furthermore, we show that the dispersion effect aids the stability of these LDH compounds. This investigation reveals that certain intercalants enhance LDH stability and alter the bandgap favourably.

MOF-derived nanocrystalline ZnO with controlled orientation and photocatalytic activity.

We show here that MOF-5, a sample Zn-based MOF, can uniquely transform into distinct zinc oxide nanostructures. Inspired by the interconversion synthesis of zeolites, we converted MOF-5 into nanocrystalline ZnO. We found the conversion of MOF-5 into ZnO to be tunable and straightforward simply by controlling the treatment temperature and choosing an appropriate structure-directing agent (SDA). Refined X-ray diffraction (XRD) patterns showed that a synthesis temperature of 180 °C (sample ZnO-180) was optimal for achieving high crystallinity. We examined ZnO-180 with high-resolution transmission electron microscopy (HRTEM), which confirmed that the samples were made of individual crystallites grown along the c-axis, or the (001) direction, thus exposing lower energy surfaces and corroborating the XRD pattern and the molecular dynamics calculations. Further investigations revealed that the obtained ZnO at 180 °C has a superior photocatalytic activity in degrading methylene blue to other ZnO nanostructures obtained at lower temperatures.

Bispropylurea bridged polysilsesquioxane: A microporous MOF-like material for molecular recognition.

Microporous organosilicas assembled from polysilsesquioxane (POSS) building blocks are promising materials that are yet to be explored in-depth. Here, we investigate the processing and molecular structure of bispropylurea bridged POSS (POSS-urea), synthesised through the acidic condensation of 1,3-bis(3-(triethoxysilyl)propyl)urea (BTPU). Experimentally, we show that POSS-urea has excellent functionality for molecular recognition toward acetonitrile with an adsorption level of 74 mmol/g, which compares favourably to MOFs and zeolites, with applications in volatile organic compounds (VOC). The acetonitrile adsorption capacity was 132-fold higher relative to adsorption capacity for toluene, which shows the pores are highly selective towards acetonitrile adsorption due to their size and arrangement. Theoretically, our tight-binding density functional and molecular dynamics calculations demonstrated that this BTPU based POSS is microporous with an irregular placement of the pores. Structural studies confirm maximal pore sizes of ∼1 nm, with POSS cages possessing an approximate edge length of ∼3.16 Å.

Highly catalytically active CeO2-x-based heterojunction nanostructures with mixed micro/meso-porous architectures.

The architectural design of nanocatalysts plays a critical role in the achievement of high densities of active sites but current technologies are hindered by process complexity and limited scaleability. The present work introduces a rapid, flexible, and template-free method to synthesize three-dimensional (3D), mesoporous, CeO2-x nanostructures comprised of extremely thin holey two-dimensional (2D) nanosheets of centimetre-scale. The process leverages the controlled conversion of stacked nanosheets of a newly developed Ce-based coordination polymer into a range of stable oxide morphologies controllably differentiated by the oxidation kinetics. The resultant polycrystalline, hybrid, 2D-3D CeO2-x exhibits high densities of defects and surface area as high as 251 m2 g-1, which yield an outstanding CO conversion performance (T90% = 148 °C) for all oxides. Modification by the creation of heterojunction nanostructures using transition metal oxides (TMOs) results in further improvements in performance (T90% = 88 °C), which are interpreted in terms of the active sites associated with the TMOs that are identified through structural analyses and density functional theory (DFT) simulations. This unparalleled catalytic performance for CO conversion is possible through the ultra-high surface areas, defect densities, and pore volumes. This technology offers the capacity to establish efficient pathways to engineer nanostructures of advanced functionalities for catalysis.

Ultrasound-engineered synthesis of WS2@CeO2 heterostructure for sonocatalytic degradation of tylosin.

The main aim of the present investigation was the intercalation of WS2 nanosheets in the structure of ceria (CeO2) to be used for the efficient catalytic destruction of tylosin (TYL) as a macrolide antibiotic in water. As-synthesized heterostructured catalyst was placed in a sono-reactor (40 kHz and 300 W) in order to degrade TYL through the sonocatalysis. 15 wt% WS2/CeO2 was chosen for performing the systematic experiments. Decreasing the concentration of TYL, along with increasing the WS2/CeO2 dosage led to reduced degradation efficiency. The water hardness was demonstrated to be a suppressive agent on the sonocatalysis of the target pollutant. As-generated holes, OH, and also O2- were responsible for the degradation of TYL. Increasing the ultrasound power and operating temperature enhanced the degradation efficiency. The degradation rate boosted up when the temperature was raised from 10 °C (0.0107 1/min) to 40 °C (0.0165 1/min). Moreover, the lowest activation energy (Ea) for sonocatalytic degradation was obtained as 10.81 kJ/mol. The sonocatalytic activity of WS2/CeO2 in the sono-reactor encountered insignificant change within five consecutive operational runs (~15% reduction). The mechanism and pathways of the sonocatalytic decomposition of TYL are also proposed.

Polyhydroxyalkanoates (PHA): From production to nanoarchitecture.

Among many biodegradable and biocompatible biopolymers, polyhydroxyalkanoates (PHAs), generated by microorganisms, have highly attracted attention in various fields due to their unique physicochemical properties. So far, various types of progresses have been made in environmental and engineering fields by employing PHAs. Recently, employing PHAs for nanoarchitecture has become a newly emerging trend among researchers. The intrinsic nature of PHAs has dragged them towards fabrication of nanoparticles and nanocomposites. PHAs integration with nanoparticles has been vastly noted and applied in various areas such as drug delivery, antibacterial agents and bioengineering. Here, a brief review is given to how PHAs act and are produced by microorganisms, demonstrating their properties and finally, their most recent applications are discussed in nanoarchitecture and the ways they are manipulated in the fabrication of nanomaterials. This review can shed light on the exhaustive understanding of PHA capability in nanoarchitectural basics toward the development of advanced nanomaterials in many fields such as medicine, catalysis, sensor, and adsorbents.