A o-tolidine based triazine (TTP) covalent organic framework was prepared, and successful formation of the porous polymer network was confirmed by solid state 13C and 15N CP-MAS NMR spectra, XRD, and ...other morphological techniques. The synthesized TTP was decorated with transition metal/metal oxide nanoparticles (Cu, Ni, and Cu–Ni). The presence of CuO and NiO nanoparticles on the TTP matrix were confirmed by Raman spectroscopy and the PXRD analysis and different morphologies with modest changes in particle size and porosity were confirmed by FE-SEM and HR-TEM studies. As evidenced by onset potential and current density, the Cu-TTP sample exhibited excellent electrocatalytic activity for the electrochemical carboxylation of propylene oxide in the presence of CO2 and HER, whereas the Ni-TTP sample displayed excellent OER activity. The presence of pyridinic, pyrrolic, and quaternary nitrogen was attributed to the excellent catalytic activity of Cu-TTP for electrocarboxylation and HER activity, whereas secondary amine bonds and a combination of mechanisms were responsible for the increased OER activity of Ni-TTP the sample, as evidenced by XPS.
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•o-tolidine based triazine POP modified with transition metal oxide NPs were prepared.•Cu@Cu2O composite shows large surface-to-volume ratio and abundant active sites.•Cu-TTP showed excellent electrocatalytic activity towards CO2RR and HER.•Presence of secondary amine in Ni-TTP provided low overpotential towards OER.
We designed D-π-D porphyrin molecules as crystalline, hydrophobic, and p-type conductive with a desired surface energy to the perovskite up-layer via molecular engineering process. The device ...exhibited superior operational stabilities with high power conversion efficiency of 12.88% under AM 1.5 G (100 mW·cm−2) illumination.
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•Crystalline D-π-D porphyrins via low-temperature high yield chemical process.•Porphyrins exhibit higher charge carrier density compare with traditional materials.•CPPH exhibit better electrical conductivity than it’s H/ZPPHT.•Devices made using CPPHT HTM has shown conversion efficiency of 12.88%.
Crystalline, electrically conductive molecules that transport charge carriers efficiently are candidates for next–generation printable optoelectronic devices. Here, we have designed a series of D-π-D porphyrin molecular systems as either a free-base or with coordinated metals (Cu and Zn) via high yield, low-temperature synthetic procedures. The D-π-D porphyrin molecular systems (coded as HPPHT, CPPHT and ZPPHT) were comprehensively investigated employing electrical and electrochemical methods, optical absorption spectroscopy, XRD, and XPS to identify their energy levels, optical, electrical and structural properties. The studies revealed that the D-π-D porphyrin molecular systems were crystalline, with desirable energy levels and superior electrical properties compared to the benchmark Spiro-OMeTAD under similar conditions. Among these molecular systems, CPPHT exhibited an activation energy of 0.13 eV and a higher charge carrier density (Nd ~ 4.84 × 1013 cm−3), when compared to the HPPHT (4.20 × 1011 cm−3, 0.13 eV) and ZPPHT (1.92 × 1012 cm−3, 0.17 eV) systems. These molecular systems were introduced as hole transport materials into pre-made perovskite solar cells (without a HTM) by a simple infiltration process via the front contact layer. Among the three systems studied, CPPHT solar cells showed the highest photo-current density (Jsc) of 20.44 mA·cm−2 and power conversion efficiency (PCE) of 11.76% when compared with the H/ZPPHT devices under AM 1.5G (100 mW·cm−2) illumination; signifying lower recombination at the interface of the CPPHT/perovskite (MAPbI3). Incorporation of Li-TFSI/t-BP additives on the device surface improved the HTM-MAPbI3 interface, and increased the Jsc to 21.35 mA·cm−2 with a PCE of 12.88% for CPPHT devices. These D-π-D porphyrin molecular systems under ambient conditions demonstrated excellent short-term and operational stability in the presence of moisture. The modified device architecture opens up a novel configuration for designing high–performance optoelectronic devices.
Honeycomb platinum was electrodeposited from an aqueous solution of K
2PtCl
4 and H
2SO
4 in a simple one step procedure using hydrogen bubbles as a dynamic template. SEM studies revealed the ...structure to consist of interconnecting pores with sizes from 5 to 10
μm, with fine structure consisting of nodules of 100 to 200
nm with sharp extrusions that exhibited excellent electrocatalytic activity for methanol oxidation. The simplicity of the method and the quality of the surfaces prepared suggest applications in catalysis where a convenient method to prepare high surface area platinum in one step is desirable.
► A direct method to deposit a 3D honeycomb Pt structure. ► Pt structure has pore sizes 5 to 10
μm and jagged nanostructure. ► Honeycomb structure shows good activity for methanol oxidation.
Mimicking natural objects such as flowers, is an objective of scientists not only because of their attractive appearance, but also to understand the natural phenomena that underpin real world ...applications such as drug delivery, enzymatic reactions, electronics, and catalysis, to name few. This article reviews the types, preparation methods, and structural features of flower‐like structures along with their key applications in various fields. We discuss the various types of flower‐like structures composed of inorganic, organic‐inorganic hybrid, inorganic‐protein, inorganic‐enzyme and organic compositions. We also discuss recent development in flower‐like structures prepared by self‐assembly approaches. Finally, we conclude our review with the future prospects of flower‐like micro‐structures in key fields, being biomedicine, sensing and catalysis.
In this review, we described general approaches towards supramolecular self‐assembly of organic, metal‐organic, metal‐protein, metal‐enzyme hybrid materials for the formation of flower‐like superstructures. These flowers shown to be high surface‐to‐volume ration and further used for various applications such as catalysis, drug delivery to name few. We give brief overview in the mimicking natural flowers via artificial‐way by controlling various stimulus is discussed.
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•Chemical conversion from (Zn5(CO3)2(OH)6) to ZnO using Ca(OH)2 to form CaO/ZnO.•CaO/ZnO synthesized at 50 °C for 12 h were compared in dry and humid conditions.•Excellent sensitivity ...and faster response were observed at 150 °C to 500 ppm CO2 gas.•High repeatability and negligible cross-response in presence of 10 common analytes.•Performance enhancement due to n-n nanointerfaces and high surface area morphology.
Tailored synthesis of heterostructures for low temperature (sub 200 °C) CO2 sensing continues to be a challenging task. The present study demonstrates CO2 sensing characteristics of CaO-ZnO heterostructures achieved by zinc hydroxide carbonate (Zn5(CO3)2(OH)6) conversion to ZnO using Ca(OH)2 at 50 °C. Control samples namely, Zn5(CO3)2(OH)6, Ca(OH)2, ZnO, and CaO integrated microsensors exhibited low sensitivity towards CO2 gas. However, CaO-ZnO heterostructures demonstrated significant sensitivity (26 to 91%) at 150 °C for gas concentration ranging from 100 to 10000 ppm, respectively. In this study, zinc hydroxide carbonate sensitized with 25 wt% Ca(OH)2 to form CaO-ZnO heterostructures (25CaZMS) displayed a promising sensitivity (77%) and selectivity (98%) towards 500 ppm CO2 gas. Moreover, the selectivity studies were conducted in the presence of 10 commonly found gases and their sensing performance was compared against CO2 gas in dry and humid conditions. The developed CaO-ZnO sensor exhibited faster kinetics in comparison to the control samples. Improved sensing performance observed here is attributed to the low-temperature synthesis route which resulted in a large number of active pores and high surface area morphology. Additionally, the high CO2 adsorption capacity of CaO combined with compatible n-type semiconductors in forming highly dynamic nano-interfaced heterostructure is a promising step towards developing a precise CO2 gas microsensor.
We designed an asymmetric organic-molecule with high electrical property and low hole-reorganization energy and their applications.
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•Low hole-reorganization energy asymmetrical ...organic molecules were synthesized.•Phenyl-π-spacers affect was analyzed on these molecules.•OHM1 and OHM2 shows wide application in organic/perovskite solar cells.
We designed and synthesized two small unsymmetrical phenanthro-imidazole/phenothiazine molecules with (OHM-2) and without (OHM-1) a phenyl-π-spacer. The optical and electrochemical properties were measured to determine the band-gap and HOMO energy values of these molecules. It was observed that the phenyl-π-spacer played a crucial-role in lowering the hole-reorganization energy, extending the conjugation for improved electrical properties, and tuning the optical/electrochemical properties for optoelectronic applications. An alkyl-chain introduced on structure increased the hydrophobicity, improving stability in ambient atmosphere applications. Unsymmetrical phenanthro-imidazole/phenothiazine molecules were shown to be a suitable, versatile hole-transporting material for high–performance optoelectronic devices.
The alkaline oxygen evolution reaction (OER) remains a bottleneck in green hydrogen production owing to its slow reaction kinetics and low catalytic efficiencies of earth abundant electrocatalysts in ...the alkaline OER reaction. This study investigates the OER performance of hierarchically porous cobalt electrocatalysts synthesized using the dynamic hydrogen bubble templating (DHBT) method. Characterization studies revealed that electrocatalysts synthesized under optimized conditions using the DHBT method consisted of cobalt nanosheets, and hierarchical porosity with macropores distributed in a honeycomb network and mesopores distributed between cobalt nanosheets. Moreover, X-ray photoelectron spectroscopy studies revealed the presence of Co(OH)2 as the predominant surface cobalt species while Raman studies revealed the presence of the cubic Co3O4 phase in the synthesized electrocatalysts. The best performing electrocatalyst required only 360 mV of overpotential to initiate a current density of 10 mA cm−2, exhibited a Tafel slope of 37 mV dec−1, and stable OER activity over 24 h. The DHBT method offers a facile, low cost and rapid synthesis approach for preparation for highly efficient cobalt electrocatalysts.
A graphene nanoplate-supported spinel CuFe₂O₄ composite (GNPs/CuFe₂O₄) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution ...transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the prepared composite. The arsenic adsorption behavior of the GNPs/CuFe₂O₄ composite was investigated by carrying out batch experiments. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, where the sorption kinetics of arsenic adsorption by the composite were found to be pseudo-second order. The selectivity of the adsorbent toward arsenic over common metal ions in water was also demonstrated. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled column filter test. The GNPs/CuFe₂O₄ composite exhibited significant, fast adsorption of arsenic over a wide range of solution pHs with exceptional durability, selectivity, and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solution. The highly sensitive adsorption of the material toward arsenic could be potentially employed for arsenic sensing.
Ceria cubes decorated with manganese oxide nanoparticles (Mn2O3/CeO2 nanocubes) were synthesized and used to modify a Au electrode for analysis of As(III) in aqueous solution. This modified electrode ...displayed improved sensitivity than either oxide on their own, indicating a synergistic effect due to the effect of Mn2O3 on the properties of CeO2. The improved sensitivity could be ascribed to the enhanced As (III) adsorption ability of Mn2O3/CeO2 nanocube during electrochemical pre‐concentration, combined with the well known As(III) sensing qualities of the gold substrate. The Mn2O3/CeO2 nanocube modified gold electrode behaved as a promising sensor with stable, repeatable square wave anodic stripping voltammetry (SWASV) peaks, separated from common interfering ions in natural water including Cu (II) under practical conditions. Repeatability and stability studies revealed the As (III) sensor to be robust and reliable, with a sensitivity of 0.0414 μA/ppb and a limit of detection (LoD) of 3.35 ppb under optimized conditions, indicating a possible general use of this class of heteronanostructures in electroanalytical chemistry for studies that rely upon adsorption of deposition of the analyte prior to stripping analysis.
The fabrication of controlled supramolecular nanostructures via self-assembly of protoporphyrin IX (PPIX) was studied with enantiomerically pure l-arginine and d-arginine, and we have shown that ...stoichiometry controlled the morphology formed. The nanostructure morphology was mainly influenced by the delicate balance of π-π stacking interactions between PPIX cores, as well as H-bonding between the deprotonated acidic head group of PPIX with the guanidine head group of arginine. PPIX self-assembled with l-/d-arginine to create rose-like nanoflower structures for four equivalents of arginine that were 5-10 μm in length and 1-4 μm diameter. We employed UV-vis, fluorescence spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FT-IR) techniques to characterize the resulting self-assembled nanostructures. Furthermore, we investigated the catalytic activity of PPIX and arginine co-assembled materials. The fabricated PPIX-arginine nanostructure showed high enhancement of photocatalytic activity through degradation of rhodamine B (RhB) with a decrease in dye concentration of around 78-80% under simulated visible radiation.
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