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This review critically summarizes nanoporous MOFs and their hybrids/derivatives for oil–water application in the form of filtration materials, absorbents and adsorbents including their recent progress in synthesis, design, and critical challenges.

Doping and compositional tuning of Cs(2)AInCl(6) (A = Ag, Na) double perovskite nanocrystals (PNCs) is considered a promising strategy toward the development of light-emitting sources for applications in solution-processed optoelectronic devices. Oleic acid and oleylamine are by far the most often used surface capping ligands for PNCs. However, the undesirable desorption of these ligands due to proton-exchange reaction during isolation and purification processing results in colloidal and structural instabilities. Thus, the improvement of colloidal and optical stability of PNCs represents one of the greatest challenges in the field. Here, we report a trioctylphosphine-mediated synthesis and purification method toward Sb-alloyed Cs2NaInCl6 PNCs with excellent stability and optical features. Nuclear magnetic resonance spectroscopy enabled one to explain the role of trioctylphosphine and to reveal the reaction mechanism during crystal nucleation and growth. Under the optimized reaction conditions, in situ-generated trioctylphosphonium chloride and benzoyl trioctylphosphonium chloride serve as highly reactive halide sources, while benzoyl trioctylphosphonium and oleylammonium cations together with the oleate anion serve as surface capping ligands, which are bound strongly to the PNC surface. The tightly bound ionic pair of oleylammonium oleate and benzoyl trioctylphosphonium chloride/oleate ligands allows one to obtain monodispersed bright-blue-emitting PNCs with high photoluminescence quantum yields exceeding 50% at an optimum Sb content (0.5%), which also exhibit long-term colloidal stability. The approach based on dual cationic ligand passivation of double PNCs opens the doors for applications in other systems with a potential to achieve higher stability along with superior optical properties. Web of Science 13 40 47859 47845

Magnetic iron oxide nanocrystals (MIONs) are established as potent theranostic nanoplatforms due to their biocompatibility and the multifunctionality of their spin-active atomic framework. Recent insights have also unveiled their attractive near-infrared photothermal properties, which are, however, limited by their low near-infrared absorbance, resulting in noncompetitive photothermal conversion efficiencies (PCEs). Herein, we report on the dramatically improved photothermal conversion of condensed clustered MIONs, reaching an ultrahigh PCE of 71% at 808 nm, surpassing the so-far MION-based photothermal agents and even benchmark near-infrared photothermal nanomaterials. Moreover, their surface passivation is achieved through a simple self-assembly process, securing high colloidal stability and structural integrity in complex biological media. The bifunctional polymeric canopy simultaneously provided binding sites for anchoring additional cargo, such as a strong near-infrared-absorbing and fluorescent dye, enabling in vivo optical and photoacoustic imaging in deep tissues, while the iron oxide core ensures detection by magnetic resonance imaging. In vitro studies also highlighted a synergy-amplified photothermal effect that significantly reduces the viability of A549 cancer cells upon 808 nm laser irradiation. Integration of such-previously elusive-photophysical properties with simple and cost-effective nanoengineering through self-assembly represents a significant step toward sophisticated nanotheranostics, with great potential in the field of nanomedicine.

This research discusses the CO

This research discusses the CO2 valorization via hydrogenation over the non-noble metal dusters of Ni and Cu supported on graphitic carbon nitride (g-C3N4). The Ni and Cu catalysts were characterized by conventional techniques including XRD, AFM, ATR, Raman imaging, and TPR and were tested via the hydrogenation of CO2 at 1 bar. The transition-metal-based catalyst designed with atom-economy principles presents stable activity and good conversions for the studied processes. At 1 bar, the rise in operating temperature during CO2 hydrogenation increases the CO(2 )conversion and the selectivity for CO and decreases the selectivity for methanol on Cu/CN catalysts. For the Ni/CN catalyst, the selectivity to light hydrocarbons, such as CH4, also increased with rising temperature. At 623 K, the conversion attained ca. 20%, with CH4 being the primary product of the reaction (CH4 yield >80%). Above 700 K, the Ni/CN activity increases, reaching almost equilibrium values, although the Ni loading in Ni/CN is lower by more than 90% compared to the reference NiREF catalyst. The presented data offer a better understanding of the effect of the transition metals' small metal cluster and their coordination and stabilization within g-C3N4, contributing to the rational hybrid catalyst design with a less-toxic impact on the environment and health. Bare g-C3N4 is shown as a good support candidate for atom-economy-designed catalysts for hydrogenation application. In addition, cytotoxicity to the keratinocyte human HaCaT cell line revealed that low concentrations of catalysts particles (to 6.25 mu g mL(-1)) did not cause degenerative changes. Web of Science

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC(3)N(4)) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC(3)N(4) shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm(2) the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC(3)N(4)) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC(3)N(4) show a smaller charge-transfer resistance (R-Ct) of 2950 omega and long-term potential, as well as current stability of 50 h and 20 mA/cm(2), respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC(3)N(4) from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction. Web of Science 12 12 art. no. 1560

Herein we report a one-step, low cost, photocatalytic method for the synthesis of graphene oxide (GO) from commercial graphite using grey TiO2 as a photocatalyst. GO formation is achieved by UV-illumination of a slurry of well-dispersed grey TiO2 and commercial graphite. Light-induced valence-band holes from grey TiO2 then lead to an oxidation and exfoliation of graphite, resulting in the formation of visible-light-active GO. An optimal level of graphite oxidation can be established by controlling the UV illumination time. Moreover, the resulting GO-decorated TiO2 is directly active as a visible-light-active photocatalyst that can, for example, be used for pollution degradation. Web of Science art. no. e202100274

In the present work, we report a preparation strategy for hematite phase-pure photoanodes consisting of Sn-doped hematite nanoflakes/hematite thin film bilayer nanostructure (Sn-HB). This approach is based on a two-step annealing process of pure iron films deposited on fluorine doped tin oxide (FTO) substrates by advanced magnetron sputtering. While the high density hematite ultrathin nanoflakes (HNs) with detrimental iron oxide layers (Fe3O4 and/or FeO) are generated during the first annealing step at 400 degrees C for two hours, the second thermal treatment at 800 degrees C for 15 minutes oxidises all the undesired iron oxide phases to a photoactive hematite layer as well as is providing efficient Sn doping of a drop-casted SnCl4 in order to increase the conductivity. The optimized Sn-HB shows an around 11 times higher photocurrent density (0.71 mA cm(-2) at 1.23 V-RHE) compared with a reference hematite photoanode produced from iron foil under the same conditions. Web of Science 9 11 art. no. E202200066

In the present work the authors show that anodic TiO

Doping and compositional tuning of Cs

Fully fluorinated graphene (fluorographene) exhibits a weak nonlinear optical response, in contrast to its unfunctionalized counterpart, graphene. However, diethyl-amino-functionalized fluorographene is shown to exhibit a dramatic enhancement of its nonlinear optical response. Diethyl-amino-fluorographene is obtained by the reaction of fluorographene with lithium diethylamide. Partial nucleophilic substitution/reduction of the substrate results in sp3 carbons bonded to diethylamine or fluorine groups and in distinct sp2 domains. The diethylamine groups act as strong electron donors, the C–F groups as strong electron acceptors, and the sp2 domains as π-conjugated bridges, thus forming a donor−π bridge–acceptor nonlinear optical chromophore scheme. As such, the diethyl-amino-fluorographene displays a large enhancement of its nonlinear optical response compared to fluorographene and other fluorographene derivatives under ps, both visible and infrared laser excitation.

A category of naked maghemite nanoparticles (γ-Fe2O3), named surface active maghemite nanoparticles (SAMNs), is characterized by biological safety, high water colloidal stability and a surface chemistry permitting the binding of ligands. In the present study, the interaction between SAMNs and an antibiotic displaying chelating properties (oxytetracycline, OxyTC) was extensively structurally and magnetically characterized. OxyTC emerged as an ideal probe for providing insights into the colloidal properties of SAMNs. At the same time, SAMNs turned out as an elective tool for water remediation from OxyTC. Therefore, a dilute colloidal suspension of SAMNs was used for the removal of OxyTC in large volume tanks where, to simulate a real in situ application, a population of zebrafish (Danio rerio) was introduced. Interestingly, SAMNs led to the complete removal of the drug without any sign of toxicity for the animal model. Moreover, OxyTC immobilized on SAMNs surface resulted safe for sensitive Escherichia coli bacteria strain. Thus, SAMNs were able to recover the drug and to suppress its antibiotic activity envisaging their feasibility as competitive option for water remediation from OxyTC in more nature related scenarios. The present contribution stimulates the use of novel smart colloidal materials to cope with complex environmental issues.

In the present work we introduce a simple approach to produce porous PtPdAg alloy nanoparticles on TiO2 nanotubes by a simple combined sputtering-dewetting-dealloying process. In a first step, three individual metals (Pt, Pd and Ag) were sequentially sputter-deposited on spaced TiO2 nanotubes, followed by a thermal dewetting treatment in Ar to convert these metal layers into ternary PtPdAg alloyed particles. Dealloying was carried out by a selective chemical dissolution of Ag in piranha solution that finally generated porous alloyed nanoparticles located on the TiO2 nanotube walls. The porous PtPdAg-decorated TiO2 nanotubes show enhanced photocatalytic H2 generation in comparison with porous Pt (67% increase) or any monometallic decoration (>120% increase). The photocatalytic enhancement is not only due to the increased number of active sites (larger surface area) of the porous particles but also due to the synergistic effects of the different alloying elements.

Ni, Cu and Cu–Ni nanostructures have been fabricated and homogeneously embedded on ultrathin two-dimensional (2D) carbon nitride (g-C3N4), and the surface morphology and composition of the resulting hybrid nanostructures were studied by XRD, TEM, HRTEM-elemental mapping, Raman spectroscopy and XPS. The new hierarchical hetero-structures dropcasted on GC anodes have been visualised by SEM and their catalytic performance have been examined in methanol electrooxidation reaction (MOR) under alkaline conditions. Nanosized Ni particles dispersed finely over g-C3N4 are very active electrocatalysts with MOR onset at potential 0.35 V and charge transfer resistance 0.12 kΩ. The stability of modyfied GC electrodes, examined under chronoamperometric conditions showed that for electrode loading with 4% (wt. %) of NiO the stable current density ca. 36 A g−1 (12 A cm2) was obtained during whole experiment (up to 160 min). For all catalyst studied the curent density obtained during MOR reaction was enhanced when electrode was iluminated by UV light λ∼400 nm, and the highest value were obtained for 4% Ni/CN catalyst ca. 127 A g−1 (22 A cm2). The Cu incorporation in the hybrid material evoke loss of activity mostly due to Cu+ irreversible reduction/oxidation to Cu° and Cu2+, CuO segregation and influencing electron transfer process which results in the increasing in the redox potential. These results represent an important step towards light-enhanced electro-reactive systems and sensors in which heterojunction formation can facilitate electron-hole separation and enable more efficient energy transfer.

Magnetic iron oxide nanocrystals (MIONs) are established as potent theranostic nanoplatforms due to their biocompatibility and the multifunctionality of their spin-active atomic framework. Recent insights have also unveiled their attractive near-infrared photothermal properties, which are, however, limited by their low near-infrared absorbance, resulting in noncompetitive photothermal conversion efficiencies (PCEs). Herein, we report on the dramatically improved photothermal conversion of condensed clustered MIONs, reaching an ultrahigh PCE of 71% at 808 nm, surpassing the so-far MION-based photothermal agents and even benchmark near-infrared photothermal nanomaterials. Moreover, their surface passivation is achieved through a simple self-assembly process, securing high colloidal stability and structural integrity in complex biological media. The bifunctional polymeric canopy simultaneously provided binding sites for anchoring additional cargo, such as a strong near-infrared-absorbing and fluorescent dye, enabling

The Stoppani factory manufactured chromium for more than one century, dumping millions of tons of Chromite Ore Processing Residues (COPRs) over decades. The massive presence of COPRs resulted in an intense Cr

A general cobalt-catalyzed N-alkylation of amines with alcohols by borrowing hydrogen methodology to prepare different kinds of amines is reported. The optimal catalyst for this transformation is prepared by pyrolysis of a specific templated material, which is generated in situ by mixing cobalt salts, nitrogen ligands and colloidal silica, and subsequent removal of silica. Applying this novel Co-nanoparticle-based material, >100 primary, secondary, and tertiary amines including N-methylamines and selected drug molecules were conveniently prepared starting from inexpensive and easily accessible alcohols and amines or ammonia., A general cobalt-catalyzed N-alkylation of amines with alcohols by borrowing hydrogen methodology to prepare different kinds of amines is reported.

Single‐atom catalysts (SACs) are highly enviable to exploit the utmost utilization of metallic catalysts; their efficiency by utilizing nearly all atoms to often exhibit high catalytic performances. To architect the isolated single atom on an ideal solid support with strong coordination has remained a crucial trial. Herein, graphene functionalized with nitrile groups (cyanographene) as an ideal support to immobilize isolated copper atoms G(CN)‐Cu with strong coordination is reported. The precisely designed mixed‐valence single atom copper (G(CN)‐Cu) catalysts deliver exceptional conversions for electrochemical methanol oxidation (MOR) and CO2reduction (CO2RR) targeting a “closed carbon cycle.” An onset of MOR and CO2RR are obtained to be ≈0.4V and ≈−0.7 versus Ag/AgCl, respectively, with single active sites located in an unsaturated coordination environment, it being the most active Cu sites for both studied reactions. Moreover, G(CN)‐Cu exhibited significantly lower resistivity and higher current density toward MOR and CO2RR than observed for reference catalysts.

A hybrid of GA@UiO-66-NH2 was synthesized based on the covalent assembly of graphene acid (GA) and the amine functionalized UiO-66 metal-organic framework through amide bonds. This strategy endows the material with unique properties, such as hierarchical pores, a porous conductive network decorated with functional groups, a high specific surface area, and a good chemical and thermal stability. The resultant hybrid has an electrical resistance of similar to 10(4) omega, whereas the pristine GA and UiO-66-NH2 possess an electrical resistance of similar to 10(2) omega and similar to 10(9) omega, respectively. The hybrid GA@UiO-66-NH2 was demonstrated for CO2 chemiresistive sensing and displayed a very fast response and quick recovery time of similar to 18 s for 100% CO2, at 200 degrees C. While the pristine GA exhibits negligible response under the same conditions, GA@UiO-66-NH2 exhibited a response of 10 +/- 0.6%. Further, in situ temperature dependent Raman studies during CO2 exposure confirm the presence of strong hydrogen bonding interaction between CO2 and the amide functionality present on GA@UiO-66-NH2. The resulting gas sensing characteristics of GA@UiO-66-NH2 are majorly attributed to the better interaction of CO2 at the amide/amine functional groups and the readily accessible hierarchical pores. This design strategy opens new horizons in the development of covalently linked hybrids with hierarchical porous conductive networks which can help to improve the gas sensing properties of MOF-based materials. Web of Science 9 32 17441 17434

Highly ordered multi-leg TiO2 nanotubes (MLTNTs) functionalized with platinized cyanographene are proposed as a hybrid photoelectrode for enhanced photoelectrochemical water splitting. The platinized cyanographene and cyanographene/MLTNTs composite yielded photocurrent densities 1.66 and 1.25 times higher than those of the pristine MLTNTs nanotubes, respectively. Open circuit VOC decay (VOCD), electrochemical impedance spectroscopy (EIS), and intensity-modulated photocurrent spectroscopy (IMPS) analyses were performed to study the recombination rate, charge transfer characteristics, and transfer time of photogenerated electrons, respectively. According to the VOCD and IMPS results, the addition of (platinized) cynographene decreased the recombination rate and the transfer time of photogenerated electrons by one order of magnitude. Furthermore, EIS results showed that the (platinized) cyanographene MLTNTs composite has the lowest charge transfer resistance and therefore the highest photoelectrochemical performance.

Hematite is a low band gap, earth abundant semiconductor and it is considered to be a promising choice for photoelectrochemical water splitting. However, as a bulk material its efficiency is low because of excessive bulk, surface, and interface recombination. In the present work, we propose a strategy to prepare a hematite (&alpha, Fe2O3) photoanode consisting of hematite nanorods grown onto an iron oxide blocking layer. This blocking layer is formed from a sputter deposited thin metallic iron film on fluorine doped tin oxide (FTO) by using cyclic voltammetry to fully convert the film into an anodic oxide. In a second step, hematite nanorods (NR) are grown onto the layer using a hydrothermal approach. In this geometry, the hematite sub-layer works as a barrier for electron back diffusion (a blocking layer). This suppresses recombination, and the maximum of the incident photon to current efficiency is increased from 12% to 17%. Under AM 1.5 conditions, the photocurrent density reaches approximately 1.2 mA/cm2 at 1.5 V vs. RHE and the onset potential changes to 0.8 V vs. RHE (using a Zn-Co co-catalyst).

The ability of peculiar iron oxide nanoparticles (IONPs) to evade the immune system was investigated in vivo. The nanomaterial was provided directly into the farming water of zebrafish ( Danio rerio) and the distribution of IONPs and the delivery of oxytetracycline (OTC) was studied evidencing the successful overcoming of the intestinal barrier and the specific and prolonged (28 days) organotropic delivery of OTC to the fish ovary. Noteworthy, no sign of adverse effects was observed. In fish blood, IONPs were able to specifically bind apolipoprotein A1 (Apo A1) and molecular modeling showed the structural analogy between the IONP@Apo A1 nanoconjugate and high-density lipoprotein (HDL). Thus, the preservation of the biological identity of the protein suggests a plausible explanation of the observed overcoming of the intestinal barrier, of the great biocompatibity of the nanomaterial, and of the prolonged drug delivery (benefiting of the lipoprotein transport route). The present study promises novel and unexpected stealth materials in nanomedicine.

In this work, we grow intrinsically Cu-doped TiO2 nanotubes (TiNTs) by self-organizing anodization of Ti–Cu binary alloys. We demonstrate that up to a copper concentration of 1.5 at.% in the alloy, self-ordered Cu2+-doped nanotubes can be grown. Under UV illumination the Cu2+ ion-doped oxide structures can be converted to nanotubes that carry metallic nanoparticles (NPs) uniformly decorated on top of the TiNTs. We investigate the formation of these metallic nanoparticles under UV illumination by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). The resulting intrinsic copper-doped and decorated TiNTs have a strongly enhanced photocatalytic activity for H2 evolution in comparison to pristine TiNTs. Key is the light-induced conversion of the intrinsic Cu dopant to metallic copper nanoparticles that act as a stable co-catalyst for H2 generation. Keywords: TiO2, Cu doped TiO2, Photocatalytic activity, Intrinsic copper decoration

Reduced titanium dioxide has recently attracted large attention, particularly for its unique co-catalyst-free H$_2$ heterogeneous photocatalytic application. The enhanced photocatalytic activity of the reduced TiO$_2$ was previously ascribed to the introduction of point crystal defects (mainly Ti$_3^+$ centers), which result in the formation of intrinsic co-catalytic centers and enhanced visible light absorption. In this work, we systematically investigate the effect of different defects in the TiO$_{2-x}$ lattice on photocatalytic H$_2$ evolution. To introduce different types of defects, thermal annealing in air (oxidative), Ar (inert), Ar/H$_2$ (reducing), and H$_2$ (reducing) atmospheres were performed on commercially available anatase nanopowder. Then, the powders were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) to clarify the effect of treatment on material properties. Furthermore, the defect types were characterized by electron paramagnetic resonance (EPR) spectroscopy. We show that thermal annealing in different atmospheres can form different amounts of different defect types in the TiO$_2$ structure. The highest photocatalytic activation is achieved by annealing the anatase powder in a reducing atmosphere for an appropriate temperature/annealing time. By combining the results from H$_2$ generation and EPR analysis we show that the simultaneous presence of two types of defects, i.e. surface exposed Ti$_3^+$ and lattice embedded Ti$_3^+$ centers, in an optimum low concentration, is the determining factor for an optimized photocatalytic H$_2$ evolution rate. In fact, annealing anatase powder under the so-reported optimized conditions in reducing atmosphere leads to the generation of a considerable amount of H$_2$, with rates as high as 338 $\mu$molh-1g-1.

We report calcium phosphate (CaP) nanocapsule crowned multiwalled carbon nanotubes (CNT–GSH–G4–CaP) as a novel platform for intracellular delivery of an anticancer drug. As a proof-of-concept, CNT–GSH–G4–CaP demonstrates release of anticancer drug doxorubicin hydrochloride (DOX) within intracellular lysosomes from the interior cavity of CNT upon pH triggered CaP dissolution. Importantly, we found that the CNT with a CaP nanolid can efficiently prevent untimely drug release at physiological pH but promotes DOX release at increased acidic milieu as observed in subcellular compartments such as lysosomes (∼5.0). This “zero premature release” characteristic is of clinical significance in delivering cytotoxic drugs, by reducing systemic toxicity and thus beneficial for the effective anticancer treatment. We envision that this pH triggered CaP crowned CNT nanosystem would lead to a new generation of self-regulated platforms for intracellular delivery of a variety of anticancer drugs.

Microporous organic polymers (MOPs) encapsulated with palladium nanoparticles (NPs) and immobilized on magnetic Co/C nanobeads show excellent activity in hydrogenation reactions of alkenes, alkynes, and nitro arenes with turnover frequencies (TOFs) up to 3000 h–1. The magnetic core of the nanobeads ensures an easy and fast recyclability for at least six consecutive runs by applying an external magnet to recapture the catalyst. The catalytic system reported here uses cross-linked toluene as a polymer structure and is readily prepared via a cost-efficient and versatile synthesis based on commercially available starting materials. The novel catalysts combine the advantages of a heterogeneous magnetic support with MOPs that prevent NPs from agglomeration or deactivation. In addition, the advantages of palladium NPs as exceedingly active catalyst due to their high surface-area-to-volume ratio are exploited. Furthermore, the polymeric structure can easily be varied by the change of the aromatic monomer. Introdu...

The pyrite iron disulfide thin films are regarded as suitable candidates for construction of low-cost photoelectrochemical (PEC) solar cells. Iron oxide hematite has attracted much attention as possibly convenient material for hydrogen production via PEC water splitting. We refer on preparation of pyrite thin films via thermal sulfidation of hematite films synthetized by a physical methodology of high power impulse magnetron sputtering (HiPIMS) and purely chemical approach of sol-gel. We studied for the first time the correlation between PEC functionality of hematite films and after their sulfidation into pyrite. The highest PEC activity of hematite films of 560 μA cm−2 at 700 mV vs. Ag/AgCl was achieved with the HiPIMS photoelectrodes. The photoefficiency dropped dramatically to 4 μA cm−2 at 600 mV vs. Ag/AgCl after the sulfidation. A significant increase of grains‘ size, residual unreacted hematite, surface defects were the main reasons for the poor photoactivity. The sol-gel produced hematite yielded photocurrent of 30 μA cm−2 and a slight increase to 40 μA cm−2 (recorded at 500 mV vs. Ag/AgCl) of the corresponding pyrite version. Both these electrodes showed also similar morphological characteristics. The structural, electronic and optical properties of the deposited films were determined using various methods e.g. Raman spectroscopy, SEM, and PDS.

Emerging sodium-selenium batteries suffer from volume expansion of the selenium cathode and shuttling effects of soluble intermediates. Confining selenium within the carbon matrix is the most adopted strategy to address these two issues, which is generally realized via a melt-infusion method. Herein, we developed a vapor-infiltration method to fabricate selenium/carbon composites that are advantageous over the melt-infusion route in terms of several aspects: it relieves the requirement of intensive mechanical mixing and simplifies the ratio optimization between selenium and carbon; it avoids selenium aggregation and makes it possible to utilize all of the surface and pores of the carbon host. Utilizing this method, we fabricated a selenium/graphene composite from thermally reduced graphene oxide with a selenium loading equal to 71 wt %, thus approaching the record value. The obtained composite achieved the highest reported to date initial Coulombic efficiency of 88% among various selenium cathodes, with superior rate and cycle performance (410 and 367 mA h g

Au and Pt do not form homogeneous bulk alloys as they are thermodynamically not miscible. However, we show that anodic TiO2 nanotubes (NTs) can in situ be uniformly decorated with homogeneous AuPt alloy nanoparticles (NPs) during their anodic growth. For this, a metallic Ti substrate containing low amounts of dissolved Au (0.1 atom %) and Pt (0.1 atom %) is used for anodizing. The matrix metal (Ti) is converted to oxide, whereas at the oxide/metal interface direct noble metal particle formation and alloying of Au and Pt takes place; continuously these particles are then picked up by the growing nanotube wall. In our experiments, the AuPt alloy NPs have an average size of 4.2 nm, and at the end of the anodic process, these are regularly dispersed over the TiO2 nanotubes. These alloyed AuPt particles act as excellent co-catalyst in photocatalytic H2 generation, with a H2 production rate of 12.04 μL h–1 under solar light. This represents a strongly enhanced activity as compared to TiO2 NTs decorated with mon...

Over the past years, α-Fe2 O3 (hematite) has re-emerged as a promising photoanode material in photoelectrochemical (PEC) water splitting. In spite of considerable success in obtaining relatively high solar conversion efficiency, the main drawbacks hindering practical application of hematite are its intrinsically hampered charge transport and sluggish oxygen evolution reaction (OER) kinetics on the photoelectrode surface. In the present work, we report a strategy that synergistically addresses both of these critical limitations. Our approach is based on three key features that are applied simultaneously: i) a careful nanostructuring of the hematite photoanode in the form of nanorods, ii) doping of hematite by Sn4+ ions using a controlled gradient, and iii) surface decoration of hematite by a new class of layered double hydroxide (LDH) OER co-catalysts based on Zn-Co LDH. All three interconnected forms of functionalization result in an extraordinary cathodic shift of the photocurrent onset potential by more than 300 mV and a PEC performance that reaches a photocurrent density of 2.00 mA cm-2 at 1.50 V vs. the reversible hydrogen electrode.

The kinetics and mechanism of ferrate(iv), (v) and (vi) transformations in water and in polar organic solvents (namely ethanol and tetrahydrofuran) have been investigated by the method of 57Fe Mössbauer spectroscopy of frozen solutions. Ethanol with a very limited amount of water under an inert atmosphere, significantly slows down the transformation reactions of ferrates(iv and v) and provides direct proof of the existence of intermediate states. Simultaneously, ethanol is oxidized to caboxylates in the close vicinity of the surface of ferrate crystallites as proven by X-ray photoelectron spectroscopy. On the contrary, any transformation of ferrate(vi) in pure ethanol (with a very limited amount of water) was not observed. Mössbauer spectroscopy of frozen solutions enabled us to experimentally identify and quantify intermediates of ferrate(iv) and ferrate(v) transformations for the first time. Sodium ferrate(iv) in its tetrahedral form, Na4FeO4, undergoes a two-step charge disproportionation to Fe(iii) and Fe(vi) via a Fe(v) intermediate without any evolution of oxygen in polar protic and aprotic solvents, specifically 2Fe(iv) → Fe(iii) + Fe(v), and Fe(iv) + Fe(v) → Fe(iii) + Fe(vi), i.e. in sum 3Fe(iv) → 2Fe(iii) + Fe(vi). Ferrate(v) (K3FeO4) transforms to Fe(iii) and Fe(vi) without any indication of the Fe(iv) intermediate within the detection limit of the method. In addition to a charge disproportionation reaction proceeding in polar liquids, 3Fe(v) → Fe(iii) + 2Fe(vi), a competitive reduction of Fe(v) directly to Fe(iii) accompanied by oxygen evolution takes place in water. Oxygen evolution was also measured for ferrate(iv and vi) transformations in water, but to a higher and a smaller extent compared to ferrate(v), respectively. The thermodynamics of the suggested ferrate(iv) and ferrate(v) transformation pathways was examined by DFT calculations.

In this work, we describe a simple and general procedure for the purification of carbon dots. Following a hydrothermal heating procedure, the reaction mixture usually contains unreacted starting material and by-products alongside the carbon dots, which often appear among otherwise intense photoluminescence. The proposed purification method is based on a solid phase extraction technique, where the reaction mixture is absorbed on porous alumina and the carbon dots are isolated from the by-products and unreacted organics using proper solvents, and are finally recovered from the alumina using a simple extraction.

Energy storage is increasingly demanded in many new niches of applications from wearables to unmanned autonomous vehicles. However, current energy storage systems are unable to fulfill the power requirements (high energy at high power) needed for these novel applications. Recently, Li-ion capacitors (LICs) have been spotted as hybrid devices with the potential to display high energy and high power. Nevertheless, it is still a great challenge to achieve high performance LICs due to the unmatched kinetic properties and capacity between anode and cathode materials. Herein, we are presenting our first seminal report on the use of BiVO4 nanorods as a new anode material for LICs coupled with a partially reduced graphene oxide (PRGO) cathode. The BiVO4 nanorods show an excellent reversible capacity of 877 mA h g−1 (ultrahigh volumetric capacity of 4560 mA h cm−3) at 1.1 A g−1 with a great capacity retention (in half-cell design), which is the highest value reported so far for metal vanadates. Later on, a LIC was constructed with BiVO4 as the anode and PRGO as the cathode electrode, delivering a high energy density of 152 W h kg−1 and a maximum power density of 9.6 kW kg−1 compared to that for hard carbon and intercalation (such as Li4Ti5O12 and Li3VO4) based anode materials. Additionally, the BiVO4//PRGO LIC exhibits a good cyclability of 81% over 6000 cycles. Thus, this investigation opens up new opportunities to develop different LIC systems., DPD acknowledges the support of University of Adelaide, Australia for the grant of Research Fellowship (Research for Impact). Funding from MINECO (MAT2015-68394-R) is acknowledged. The ICN2 is supported by the Severo Ochoa programme of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grant no. SEV-2013-0295) and funded by the CERCA programme/Generalitat de Catalunya. K. J. R. is grateful to the Alexander von Humboldt (AvH) foundation for a post-doctoral fellowship. The authors also gratefully acknowledge support by the Catalysis Research Centre at TU Munich and the support from the Ministry of Education, Youth and Sports of the Czech Republic (LO1305) and the assistance provided by the Research Infrastructure NanoEnviCz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under project no. LM2015073. The authors gratefully acknowledge the support by the Operational Programme Research, Development and Education – European Regional Development Fund, project no. CZ.02.1.01/0.0/0.0/15_003/0000416 and the project CZ.02.1.01/0.0/0.0/16_019/0000754.

The Stoppani factory manufactured chromium for more than one century, dumping millions of tons of Chromite Ore Processing Residues (COPRs) over decades. The massive presence of COPRs resulted in an intense CrVI leaching and consequent contamination of percolating groundwater. The site offers a unique opportunity to follow COPRs evolution from the primary roasting process to the aged Cr-bearing mineral phases. Herein, new insights on COPRs mineralogy evolution and their role in CrVI release are provided by a dry sample preparation protocol, coupled with in-depth multi-technique characterization. Besides typical COPRs mineral assemblages, highly soluble Na2CrO4 and the first evidence of crocoite (PbCrO4) in a COPR contaminated site are revealed. Selective extraction experiments confirmed a strong reactivity for Cr-bearing minerals as confirmed by concentrations as high as 375 mg L−1 of leached CrVI. The mineralogical approach was combined with a nanotechnological solution for CrVI wastewater remediation. The application of naked colloidal maghemite (γ-Fe2O3) nanoparticles (SAMNs) on the complex industrial wastewater, led to > 90% CrVI removal, either under acidic or in-situ conditions. The present case study of a highly polluted site, ranging from mineral characterization to wastewater remediation, highlights the use of multidisciplinary approaches to cope with complex environmental issues.

The covalent functionalization of graphene enabling to overcome its hydrophobicity and still keeping a high conductivity is a challenging task, particularly for advanced biosensing applications. We present a facile strategy towards water dispersible nanocarbon with excellent conductive and sensing properties. Graphene–fullerol (GFL) covalent hybrid is prepared by impregnation of chemically exfoliated graphene sheets with fullerol clusters followed by thermal treatment. The partial dehydroxylation of fullerol during heating is necessary for exposing the fullerene skeleton to graphene and promoting their covalent bonding. The remaining hydroxyl and ionic groups equip the final product with good dispersibility in water (0.04 mg mL−1). Simultaneously, the GFL hybrid retains a high electrical conductivity of 0.8 × 105 S m−1, which is comparable to that of unmodified graphene. The conductive and hydroxyl-bearing derivative was successfully applied for electrochemical sensing of dopamine, hydroquinone (HQ), and catechol (C) using cyclic voltammetry. GFL modified electrodes exhibited simultaneous HQ and C detection at lower potentials compared to other nanosensors.

This paper reviews the current understanding of the toxicity of selenium (Se) to terrestrial mammalian and aquatic organisms. Adverse biological effects occur in the case of Se deficiencies, associated with this element having essential biological functions and a narrow window between essentiality and toxicity. Several inorganic species of Se (−2, 0, +4, and +6) and organic species (monomethylated and dimethylated) have been reported in aquatic systems. The toxicity of Se in any given sample depends not only on its speciation and concentration, but also on the concomitant presence of other compounds that may have synergistic or antagonistic effects, affecting the target organism as well, usually spanning 2 or 3 orders of magnitude for inorganic Se species. In aquatic ecosystems, indirect toxic effects, linked to the trophic transfer of excess Se, are usually of much more concern than direct Se toxicity. Studies on the toxicity of selenium nanoparticles indicate the greater toxicity of chemically generated selenium nanoparticles relative to selenium oxyanions for fish and fish embryos while oxyanions of selenium have been found to be more highly toxic to rats as compared to nano-Se. Studies on polymer coated Cd/Se quantum dots suggest significant differences in toxicity of weathered vs. non-weathered QD's as well as a significant role for cadmium with respect to toxicity.