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Recombination and regeneration dynamics in Fe-NHC-sensitized DSSCs revealed incomplete injection and the detrimental effect of photoinjected electron recapture by the I3-form of the redox electrolyte on performance. Importantly, the use of additives in the electrolyte allowed the best efficiency ever recorded for an iron-based DSSC to be reached.

In this contribution we have explored the applications of WO3 based nanomaterials to the degradation of Ketoprofen and Levofloxacin, selected among the most widely used anti-inflammatory and analgesic species and antibiotics and representing thus ubiquitous water contaminants of emerging concern. Compared to conventional photocatalytic conditions, which were not effective in the oxidative degradation of Ketoprofen, the application of the electric bias was successful in promoting a 50% Ketoprofen degradation after 5 h illumination, with a degradation rate constant of 0.22 h−1. A similar improvement was found with Levofloxacin. The degradation rate was further accelerated by exploiting WO3 films modified with β25 zeolites which achieved, on the same time scale, >65% degradation with Ketoprofen and ca. 90% with Levofloxacin. The complete disappearance of the oxidation intermediates of these two drugs was observed on a time scale of ca. 20 h, indicative of the achievement of complete drug mineralization at the illuminated β25/WO3 interface under 1 sun illumination.

Water oxidation represents the anodic reaction in most of the photoelectrosynthetic setups for artificial photosynthesis developed so far. The efficiency of the overall process strongly depends on the joint exploitation of good absorber domains and interfaces with minimized recombination pathways. To this end, we report on the effective coupling of thin-layer hematite with amorphous porous nickel-iron oxide catalysts prepared via pulsed laser deposition. The rational design of such composite photoelectrodes leads to the formation of a functional adaptive junction, with enhanced photoanodic properties with respect to bare hematite. Electrochemical impedance spectroscopy has contributed to shed light on the mechanisms of photocurrent generation, confirming the reduction of recombination pathways as the main contributor to the improved performances of the functionalized photoelectrodes. Our results highlight the importance of the amorphous catalysts' morphology, as dense and electrolyte impermeable layers hinder the pivotal charge compensation processes at the interface. The direct comparison with all-iron and all-nickel catalytic counterparts further confirms that control over the kinetics of both hole transfer and charge recombination, enabled by the adaptive junction, is key for the optimal operation of this kind of semiconductor/catalyst interfaces.

Chronic skin wounds represent a major global health problem and financial burden. The blocked healing process of chronic wounds involves excess inflammatory proteins, persistent microbial burden, and often, drug-resistant biofilm on the wound bed. Wound-bed debridement is considered crucial to restart the healing process.The authors developed a novel desiccant (desiccating agent A) to serve as a new form of chemical debridement. The objective is to establish the working mechanism of desiccating agent A.Desiccating agent A was exposed to 7 pathogens in vitro and a prospective trial investigation was performed in vivo on 10 cases to establish a timeline to reach granulation.The growth of a pool of the 7 pathogens showed an inhibition ring at 24 hours was 54 mm ± 5 mm. The prospective trial investigating 10 cases (5 females, 5 males) had a median age of 72.5 years (range, 50-90 years). The duration of the ulcers ranged from 6 weeks to 52 weeks (interquartile range, 6-24 weeks). The wound bed (median area, 64 cm2) was rinsed and dried. Desiccating agent A was applied directly to the wound bed with a gloved finger; after 30 to 60 seconds, desiccating agent A was rinsed and the remaining desiccated material was mechanically removed with dry sterile gauze. The wound bed was dried and covered with sterile gauze soaked in fitostimoline; dressings were changed as needed. The only observed side effect, transient pain, graded on a visual analog scale. Pain intensity ranged from 1 to 7 on a scale from 0 to 10. No nodules, welts, or blisters were observed. Median time to full granulation was 20.5 days (range, 7-78 days).These data support continued development of desiccating agent A as a chemical debridement agent.

Dye-sensitized solar cells (DSSCs) emerged in the early 1990s as a promising alternative to the classic silicon-based solar cell due to their unique combination of low cost, ease of fabrication, color palette for building integration, and high efficiency in indoor applications. This review article describes the fabrication and the properties of poly (3,4-ethylenedioxythiophene) (PEDOT)-based catalytic counter electrodes (CEs) for DSSCs. In particular, the electrochemical reactivity PEDOT CEs used in conjunction with alternative redox mediators for DSSCs is outlined. Among alternative redox shuttles, cobalt and copper complexes, as well as totally organic thiolate/disulfide, have been considered. Finally, PEDOT can also be used as a hole conductor material in electrolyte-free solid-state dye-sensitized solar cells. This review clearly shows that the progress in DSSCs development is strongly linked to the introduction of PEDOT as a new counter electrode material.

The development of new materials and prototypes with a sustainable approach to allow an efficient removal from water sources of emergent contaminants, such as drugs and antibiotics, currently represents the next challenging task in the water decontamination field. A modular photoelectrocatalytic reactor composed by single-element devices is here presented. Each single device is a stand-alone system based on a photoelectrochemical cell, which is composed by a WO 3 photoanode integrated in a tandem cell configuration with photovoltaic solar cells. Outstanding abatement results of different emerging contaminants (Atenolol, Carbamazepine, and Levofloxacin) in aqueous solution were obtained through photoelectrochemical degradation tests using the single stand-alone device. In addition, 4-Hydroxybenzaldehyde was selected as representative of natural organic matter, usually present in a real matrix. Herein, it has been proved that the system performance was optimal also for complex mixtures.

The main route of the transmission of the SARS-CoV-2 virus is through airborne small aerosol particles containing viable virus as well as through droplets transmitted between people within close proximity. Transmission via contaminated surfaces has also been recognized as an important route for the spread of SARS-CoV-2 coronavirus. Among a variety of antimicrobial agents currently in use, polymers represent a class of biocides that have become increasingly important as an alternative to existing biocidal approaches. Two transparent polymeric compounds, containing silver and benzalkonium ions electrostatically bound to a polystyrene sulfonate backbone, were synthesized, through simple procedures, and evaluated for their antimicrobial properties against Gram-positive and Gram-negative bacteria and Candida albicans (ISO EN 1276) and for their antiviral activity toward 229E and SARS-CoV-2 coronaviruses (ISO UNI EN 14476:2019). The results showed that the two tested formulations are able to inhibit the growth of (1.5-5.5) × 1011 CFU of Gram-positive bacteria, Gram-negative bacteria, and of the fungal species Candida albicans. Both compounds were able to control the 229E and SARS-CoV-2 infection of a target cell in a time contact of 5 min, with a virucidal effect from 24 to 72 h postinfection, according to the European Medicines Agency (EMA) guidelines, where a product is considered virucidal upon achieving a reduction of 4 logarithms. This study observed a decrease of more than 5 logarithms, which implies that these formulations are likely ideal candidates for the realization of transparent surface coatings that are capable of maintaining remarkable antibacterial activity and SARS-CoV-2 antiviral properties over time.

International audience; A series of six new Fe(II)NHC-carboxylic sensitizers with their ancillary ligand decorated with functions of varied electronic properties have been designed with the aim to increase the metal-to- surface charge separation and light harvesting in iron-based Dye-sensitized solar cells (DSCCs). ARM130 scored the highest efficiency ever reported for an iron-sensitized solar cell (1.83%) using Mg 2+ and NBu 4 I-based electrolyte and a thick 20μm TiO 2 anode. Computational modelling, transient absorption spectroscopy and electrochemical impedance spectroscopy (EIS) revealed that the electronic properties induced by the dimethoxyphenyl substituted NHC ligand of ARM130 led to the best combination of electron injection yield and spectral sensitivity breadth.

The production of solar fuels, i.e. energy-rich molecules obtained from sunlight-driven processes, represents one of the most pursued strategies to satisfy the increasing global energy demand in a sustainable way. Indeed, solar energy possesses the appealing features of being abundant, inexhaustible and widely geographically distributed, yet intermittent. Thus, a common approach consists in the development of specific devices (e.g. photoelectrochemical cells, PECs) allowing for its storage in the form of chemical energy. In order to produce viable PEC systems, the main focus should be the optimization of the light absorbing component(s), which generally comprise the exploitation of semiconductors (SCs). These materials must be efficient, durable, cheap and energetically suitable to perform the reaction(s) leading to the desired solar fuel(s). Hematite (α-Fe2O3) possesses these features, being composed by earth abundant elements, as well as being capable of harvesting a sizable portion of the solar spectrum. Its valence band maximum, more positive than the redox potential of water oxidation, makes it an interesting candidate for the photoinduced oxygen productionviawater splitting. In this short review, we will mainly discuss the capitalization on hematite properties for such process, while implementing suitable optimization techniques in its synthesis (namely nanostructuring, doping and surface functionalization). Examples of case studies also from our laboratory will be discussed, in which various hematite-based interfaces are probed using advanced characterization techniques (e.g. electrochemical impedance spectroscopy and transient photocurrent analysis). These studies aimed at gaining insights into the key processes involved in the photocurrent generation, thus contributing to the rational design of future more efficient photoactive interfaces. This is a challenging goal since at present all the reported hematite-based photoanodes display performances that are far below the maximum thermodynamically attainable photocurrent (i.e. 12.6mA/cm2). Finally, we will report on recent examples of hematite-based PEC systems yielding value-added organic compounds as the photoinduced oxidation products. This latter strategy, even if currently at its infancy, is believed to be a groundbreaking approach towards the production of organics exploiting sunlight energy in a sustainable electrochemical process.

Background: Various surface treatments have been tested for titanium implants aiming at increasing their surface biocompatibility and their biological characteristics, but also the efficiency of the implant surface will have to be improved to drastically decrease peri-implantite and mucosite. In fact, the peri-implantitis and peri-implant mucositis have a high incidence in clinical practice. The nanofabrication techniques that offer the possibility to achieve the implant surface that reduces bacterial colonization could influence the osteointegration. The aim of this research was to evaluate the bone response to titanium implants coated with a bifunctional molecule with antimicrobic activity consisting of a combination of silver ions covalently bound to titanium dioxide nanoparticles. Methods: A total of 36 implants were inserted into 18 older New Zealand white male rabbits. They had two different surfaces. The implants Control group was characterized by an acid-etched and sandblasted surface treatment, and the Test implants had an acid-etched and sandblasted surface coated with a silver ion covalently bound to titanium dioxide nanoparticles in the solution. Results: No statistically significant difference of the bone density was evidenced between Control and Test implants at two weeks (p-value = 0.623), four weeks (p-value = 0.339), and eight weeks (p-value = 0.461). Moreover, no statistically significant difference of the bone-implant contact percentage was evidenced between Control and Test implants at two weeks (p-value = 0.938), four weeks (p-value = 0.307), and eight weeks (p-value = 0.294). The effectiveness of the present investigation demonstrated no adverse effects on osseointegration, and no statistically significant differences were observed in the bone density and percentage of bone-implant contact between Test and Control implants at all the experimental time points (two, four, and eight weeks). Conclusions: Titanium implants coated with the silver-anatase solution bind very well to the bone and did not have an adverse effect on the bone tissue in a rabbit model. These facts suggest possible clinical applications for the silver composition.

In this contribution we report on an in-depth electrochemical impedance spectroscopy (EIS) study of the interfaces and processes involved in the photoelectrochemical hydrogen production by efficient p-type silicon (pSi) photocathodes, designedly functionalized with protective and catalytic layers. In particular, we have optimized the thermal evaporation of compact and conformal ultra-thin (5 nm) Ti films on pSi, with the double aim of (i) protecting the pSi surface from passivation and photocorrosion, as well as of (ii) introducing platforms with improved adhesion properties for the further functionalization with co-catalysts (in the specific, Pt nanoparticles). The best performing electrodes (labelled as pSi-5Ti-Pt) display an improved photocurrent onset ( ca. 200 mV positive shift in 1 M H 2 SO 4 ), as well as a more than doubled saturation photocurrent (up to −27 mA/cm 2 ) when compared to the unmodified pSi photocathodes. As evidenced by the EIS analysis, the proposed modifications of pSi surface led to an enhancement of the charge extraction from the semiconductor, most likely due to surface dipole effects able to reduce the resistance associated to the transport through the space charge layer. With respect to unmodified silicon, the presence of the Ti overlayer, partially oxidized to TiO 2 , also allows for a denser surface coverage of the electrodeposited Pt nanoclusters, resulting in decreased interfacial charge transfer resistance for hydrogen evolution. The proposed functionalization strategy relies on common fabrication methods (already applied at industrial level) and can be easily extended to other photoelectrode materials prone to passivation/photocorrosion and/or difficult to functionalize, thus introducing more flexibility in the choice of materials for photoelectrochemical cells.

The electrochemical properties of a series of complexes based on chelate ligands were explored with the aim of finding promising candidates for applications in high voltage organic flow cells. The combination of Co(II)/(I) and Fe(III)/(II) as the cathodic and the anodic couple leads to open circuit voltages close to 2 V and to limiting current of the order of 30 mA/cm2 in 0.3 M concentration in a mixture of Ethylene and Propylene carbonates. The best solubility was found for bis-cationic complexes as triflate (OTf) salts, reaching >0.6 M at room temperature. Potentiostatic and potentiodynamic experiments point to a substantial chemical and electrochemical stability at carbon based electrodes as well.

We present here a complete study on four synthetic environmentally friendly flavylium salts employed as sensitizers for dye-sensitized solar cells (DSSCs). The effect of several donor groups on the molecular structure of flavylium ions was investigated by combining electrochemical, spectroscopic and computational means. The computational investigation indicated that these molecules can interact strongly with the TiO2 surface by a single OH group of the dihydroxybenzene moiety, and can efficiently inject electrons into the TiO2 following the excitation of their lowest singlet states exhibiting charge transfer (CT) character. In general, all dyes within the explored series exhibited quite good regeneration efficiencies, often >= 70%, in the presence of an iodide electron donor, explaining the high IPCEs and photocurrents recorded in the presence of high lithium content electrolytes. The combination of molecular orbital calculations and electrochemical measurements has also revealed that the introduction of donor groups on the benzopyrylium ring has a generally positive effect resulting in an extended low energy light harvesting and in a potential improvement of the photoinduced charge separation at the semiconductor/dye/electrolyte interface. It also increases the reversibility of the oxidative redox processes of these bio-inspired species, a feature in favour of their long-term stability. At present the best dye within the explored series is 7-(N, N-diethylamino)-3', 4'-dihydroxyflavylium chloride based on a dialkylamine donor which is capable of delivering, under optimized conditions, a short-circuit current density of 15 mA cm(-2). This is the highest value so far obtained for synthetic analogues of anthocyanins.

The deposition of perylene diimide-based aggregates (PDI) onto wide band gap n-type Sb-doped SnO2 (ATO) was investigated with the aim of finding efficient and versatile dye-sensitized platforms :for photoelectrochemical solar fuel generation. These ATO-PDI photoanodes displayed hydrolytic stability in a wide range of pH (from 1 to 13) and revealed superior perforthances (up to 1 mA/cm(2) net photocurrent at 1 V vs SCE) compared to both WO3-PDI and: undoped SnO2-PDI when used in a photoelectrochemical setup for HBr splitting. Although ATO, SnO2, and WO3 are endowed with similar conduction band edge energetics, in ATO the presence-of a:significant density of intrabandgap states, whose occupancy Varies with the applied potential, plays a substantial role in tuning the efficiency of photoinduced charge separation and collection. Furthermore, the investigation of the charge injection kinetics confirmed that, even in the absence of applied bias, ATO and WO3 are the best substrates for the-oxidative quenching of poorly reducing PDI excited states, with at least a fraction of them injecting within

An anionic CoII complex, [Co(TTT) (NCS)3]− (TTT = 4,4′,4″-tri-tert-butyl-2,2′:6′,2″-terpyridine and NCS = isothiocyanate), was synthesized for use in dye-sensitized solar cells (DSSCs). The CoII complex was found to ion-pair with the hexacationic sensitizer [Ru(tmam)2(dcb)]6+ (tmam = 4,4′-bis(trimethylaminomethyl)-2,2′-bipyridine and dcb = 4,4′-(CO2H)2-2,2′-bipyridine) anchored to TiO2 thin films immersed in acetonitrile solution. Visible light excitation of the ion pairs resulted in excited-state injection followed by rapid static regeneration of the oxidized sensitizer (

Nanocrystalline WO3 absorbs visible light up to 470 nm and generates OH radicals via valence band injection. Therefore, it promotes the OH mediated oxidation of organic pollutants, when applied to the near UV–vis photodegradation of environmentally relevant target molecules like atenolol and carbamazepine. They both represent potentially hazardous recalcitrant contaminants of emerging concern (CEC) in waters. In the case of WO3 electrodes, a considerable acceleration of the degradation kinetics (up to 4–5 times) occurs through the application of a 1.5 V potential bias, which is instrumental to optimize the charge separation within the thin films and to maximize holes transfer rate to the electrolyte. Moreover, after sufficiently long irradiation, the complete mineralization of the organics is obtained. Interestingly, the photo-electrochemical degradation process (applied bias condition) maintains its effectiveness and a large efficiency margin over conventional open circuit conditions. Photoelectrocatalysis is observed even in diluted supporting electrolyte conditions, representing the average salinity of natural freshwater samples, demonstrating the advantageous practical feasibility of the photo-electrochemical approach.

Three perfluorinated Zn

The bacterial biofilm formation in the oral cavity and the microbial activity around the implant tissue represent a potential factor on the interface between bone and implant fixture that could induce an inflammatory phenomenon and generate an increased risk for mucositis and peri-implantitis. The aim of the present clinical trial was to investigate the bacterial quality of a new antibacterial coating of the internal chamber of the implant in vivo at six months. The PIXIT implant (Edierre srl, Genova Italy) is prepared by coating the implant with an alcoholic solution containing polysiloxane oligomers and chlorhexidine gluconate at 1%. A total of 15 healthy patients (60 implants) with non-contributory past medical history (nine women and six men, all non-smokers, mean age of 53 years, ranging from 45&ndash, 61 years) were scheduled to receive bilateral fixed prostheses or crown restorations supported by an implant fixture. No adverse effects and no implant failure were reported at four months. All experimental sites showed a good soft tissue healing at the experimental point times and no local evidence of inflammation was observed. Real-Time Polymerase Chain Reaction (PCR) analysis on coated and uncoated implants showed a decrease of the bacterial count in the internal part of the implant chamber. The mean of total bacteria loading (TBL) detected in each PCR reaction was lower in treated implants (81038 units/reaction) compared to untreated implants (90057 units/reaction) (p &lt, 0.01). The polymeric chlorhexydine coating of the internal chamber of the implant showed the ability to control the bacterial loading at the level of the peri-implant tissue. Moreover, the investigation demonstrated that the coating is able to influence also the quality of the microbiota, in particular on the species involved in the pathogenesis of peri-implantitis that are involved with a higher risk of long-term failure of the dental implant restoration.

WO

The oxygen in Earth’s atmosphere is there primarily because of water oxidation performed by photosynthetic organisms using solar light and one specialized protein complex, photosystem II (PSII). High-resolution imaging of the PSII ‘core’ complex shows the ideal co-localization of multi-chromophore light-harvesting antennas with the functional reaction centre. Man-made systems are still far from replicating the complexity of PSII, as the majority of PSII mimetics have been limited to photocatalytic dyads based on a 1:1 ratio of a light absorber, generally a Ru–polypyridine complex, with a water oxidation catalyst. Here we report the self-assembly of multi-perylene-bisimide chromophores (PBI) shaped to function by interaction with a polyoxometalate water-oxidation catalyst (Ru4POM). The resulting [PBI]5Ru4POM complex shows a robust amphiphilic structure and dynamic aggregation into large two-dimensional paracrystalline domains, a redshifted light-harvesting efficiency of >40% and favourable exciton accumulation, with a peak quantum efficiency using ‘green’ photons (λ > 500 nm). The modularity of the building blocks and the simplicity of the non-covalent chemistry offer opportunities for innovation in artificial photosynthesis. In native photosystem II (PSII), multi-chromophore antennas surround the reaction centre, capturing light and triggering the quantized (four-flashes) photo-oxidation of water to oxygen. The PSII ‘quantasome’ is the most efficient photo-electrolyser built so far. An artificial quantasome has now been developed; it is specifically designed for oxygen evolution by self-assembling light-harvesting-perylene bisimides with a ruthenium polyoxometalate water-oxidation catalyst.

Three perfluorinated ZnII porphyrins were evaluated as n-type sensitizers in photoelectrosynthetic cells for HBr and water splitting. All the dyes are featured by the presence of pentafluorophenyl electron-withdrawing groups to increase the ground-state oxidation potential and differ for the nature and position of the ?-conjugate linker between the core and anchoring group tasked to bind the metal oxide, in order to assess the best way of coupling with the semiconductor. A phenyl-triazole moiety was used to link the carboxylic anchoring group onto the meso position, while an ethynyl-phenyl linker was chosen to bridge carboxylic and cyanoacrylic groups onto the ?-pyrrolic position. A combination of electrochemical, computational, and spectroscopic investigations confirmed the strong electron-withdrawing effect of the perfluorinated porphyrin core, which assures all the investigated dyes of the high oxidation potential required to the coupling with water oxidation catalysts (WOC). Such an electron-poor core, however, affects the charge separation character of the dyes, as demonstrated by the spatial distribution of the excited states, leading to a nonquantitative charge injection, although tilting of the molecules on the semiconductor surface could bring the porphyrin ring closer to the semiconductor, offering additional charge-transfer pathways. Indeed, all the dyes demonstrated successful in the splitting of both aqueous HBr and water, with the best results found for the SnO2/TiO2 photoanode sensitized with the ?-substituted porphyrin equipped with a cyanoacrylic terminal group, achieving 0.4 and 0.1 mA/cm2 photoanodic currents in HBr and water under visible light, respectively. The faradaic yield for oxygen evolution in the presence of an IrIV catalyst was over 95%, and the photoanode operation was stable for more than 1000 s. Thus, the perfluorinated porphyrins with a cyanoacrylic anchoring group at the ?-position should be considered for further development to improve the charge-transfer character.

WO3/BiVO4 films obtained by electrochemical deposition of BiVO4 over mesoporous WO3 were applied to the photoelectrochemical degradation of selected emerging contaminants (ketoprofen and levofloxacine) in aqueous solutions. The WO3/BiVO4 films in this work are characterized by a mesoporous morphology with a maximum photoconversion efficiency >40% extending beyond 500 nm in Na2SO4 electrolytes. Oxygen was found to be the dominant water oxidation product (ca. 90% faradaic yield) and no evidence for the photogeneration of OH radicals was obtained. Nevertheless, both 10 ppm levofloxacine and ketoprofen could be degraded at WO3/BiVO4 junctions upon a few hours of illumination under visible light. However, while levofloxacine degradation intermediates were progressively consumed by further oxidation at the WO3/BiVO4 interface, ketoprofen oxidation byproducts, being stable aromatic species, were found to be persistent in aqueous solution even after 15 hours of solar simulated illumination. This indicates that, due to the lower oxidizing power of photogenerated holes in BiVO4 and a different water oxidation mechanism, the employment of WO3/BiVO4 in photoelectrochemical environmental remediation processes is much less universal than that possible with wider band gap semiconductors such as TiO2 and WO3.

In this work, we designed a tetranuclear self-assembled dye 4 (2Z907-Ag+-(Ru(TMAM))) exploiting a combination of the antenna effect and positively-charged groups designed to repel the oxidized form of cationic cobalt redox mediators, in order to reduce recombination and increase the efficiency of dye sensitized solar cells (DSSCs). Charge transfer and excited dynamics were probed by photoelectrochemical and photophysical measurements. The sensitized cell performance, recorded with a [Co(bpy)3]3+/2+ redox mediator and PEDOT counter electrode, showed an improvement when passing from Z907 to the multinuclear systems. The enhancement of the efficiency compared to Z907 resulted mainly from a superior steric and electrostatic shielding determined by the simultaneous presence of long alkyl chains and quaternary ammonia ion units in the architecture of 4.

A new 3,4-ethylenedioxythiophene (EDOT) monomer derivatized with aminopropyl-triethoxysilane (APTES-EDOT) was prepared via a simple two step reaction in high yield. The new monomer can be firmly grafted to the fluorine−tin-oxide (FTO) conductive glass, where the irreversible electro-oxidation of surface bound APTES-EDOT, in the presence of unsubstituted EDOT monomers in solution, triggers the cationic polymerization of EDOT, resulting in the incorporation of PEDOT chains into APTES-EDOT. As a result, the modified PEDOT film (Si-PEDOT) is covalently bound to the FTO surface and easily withstands mechanical stresses that are critical for the adhesion of regular PEDOT. When tested with Co(III)/(II) redox shuttles, electrodeposited Si-PEDOT films showed decreased charge transfer and mass transport resistances with respect to both platinum and conventional PEDOT films, leading to enhanced relative efficiencies (≈10%) when employed as counter electrode in transparent dye sensitized solar cells.

The photoelectrochemical properties and stability of dye sensitized solar cells containing Mn(beta-diketonato)(3) complexes, [Mn-III(acac)(3)] (1) (acac = acetylacetonate), [Mn-III(CF2)(3)] (2) (CF2 = 4,4-difluoro-1-phenylbutanate-1,3-dione), (Mn-III(DBM)(3)] (3) (DBM = dibenzoylmethanate), [Mn-II(CF2)(3)]TBA (TBA = tetrabutylammonium) (4) and [Mn-II(DBM)(3)]TBA (5), have been evaluated. At room temperature, the complexes undergo ligand exchange with 4-tert-butyl-pyridine, an additive commonly used in the solar device to reduce charge recombination at the photoanode. An increased device stability was achieved by using the Z907 dye and passivating the photoanode with short chain siloxanes. It was also found that the Mn(II)/(III) couple is involved in the dye regeneration process, instead of Mn(III)/(IV) (E-1/2 > 1 V vs. SCE) previously indicated in the literature.

The indication for using chemical devices as an adjunct of domestic oral hygiene has gained increased attention in last decades. The efficacy of chemical devices for oral biofilm control is proven by evidence from clinical studies. The purpose of this study was to assess the effect of a new oral gel named ADC to reduce oral bacterial loading investigated by means of Polymerase Chain Reaction (PCR). Materials and methods A total of 20 patients with a diagnosis of chronic periodontitis in the age group >25 years, were selected. None of these patients had received any surgical or non-surgical periodontal therapy and demonstrated radiographic evidence of moderate bone loss. The study sample was divided into two groups of 10 patients each, homogeneous by age and sex. The study group was given a little bottle containing ADC gel, while the control group was given an identical pack-containing placebo, a gel similar to ADC for consistence, colour, taste and odour. Four sites in separate quadrants were selected in each patient for testing the efficacy of the new medical device. Microbial analysis (MA) was performed at baseline and at day 15. Paired T-Test was used to detect statistical significant reduction of total bacterial loading and specific bacteria. Results Specimens of subgingival plaque from patients were investigated for the presence of six bacterial species and for total bacterial loading by quantitative PCR. There was a statistically significant reduction total bacterial loading detected pre and post treatment (p= 0.029) in the study group. In the control group the reduction of total bacterial loading was not significant (p= 0,279). The ADC gel did not show any side effects and was not observed to cause discomfort or to produce adverse reactions in time. No patient reported pain, burning, tingling sensation or numbness. Conclusion The aim of our study was to test the efficacy of a new chemical formulation with antibacterial properties to use for domestic oral hygiene with a preliminary study. Although the reported data show a statistically significant drop in total bacterial loading after treatment our limited results do not allow us to draw final conclusions about the clinical efficiency of the ADC gel. There is currently a trend in the increased use of antimicrobial agents. The effectiveness of antimicrobial therapies depends on host defence mechanisms and virulence factors. Further research, with relatively larger sample size and longer follow-up period, will be performed to better validate the efficacy of ADC gel as an effective local drug delivery agent in daily oral hygiene.

The study of redox couples based on Fe(III)/(II) and Co(II)/(I) organic complexes has demonstrated chemically reversible redox processes as well as good stability in organic solvents. These active complexes, obtained with polypyridine ligands, present low cost, low toxicity and good chemical stability. Moreover, they demonstrated fast redox kinetics and for that, they are candidate for active species in redox flow cells. A wide library of polypyridine complexes have been prepared and tested as acceptor ligands to reach an open circuit voltage up to 2 V, in a mixture of ethylene carbonate and propylene carbonate (EC/PC) chosen for their low volatility and electrochemical stability. Solubility data are presented after tuning ligand design to optimize metal-complex solubility. The best compounds were [Fe(bpy)3]Tf2 (Tf = CF3SO3−, bpy = 2.2′-bipyridine) and [Co(bpy)3]Tf2 which generated current densities of the order of 30 mA/cm2 in thin layer static cells. These complexes were also preliminary tested in a complete flow cell equipped with a Nafion membrane, with LiTf electrolyte, and ca. 90% coulombic efficiency was observed. The decrease of performance observed after 8 h is under investigation and assigned, for now, to membrane degradation. A change of membrane characteristics should be considered to exploit the full potentiality of these redox mediators.

We present here a complete study on four synthetic environmentally friendly flavylium salts employed as sensitizers for dye-sensitized solar cells (DSSCs). The effect of several donor groups on the molecular structure of flavylium ions was investigated by combining electrochemical, spectroscopic and computational means. The computational investigation indicated that these molecules can interact strongly with the TiO

We report here on the preparation and on the electronic properties of a panchromatic Ru(ii) sensitizer based on a new ligand which allows for higher molar extinction coefficients in the visible and better performances (32% efficiency improvement) over conventional "black dye" in transparent DSSC.

Background. Titanium is the gold standard for dental implants, since it has demonstrated excellent biocompatibility and osseointegration properties. The rate of osseointegration is however affected by the surface morphology and peri-implant infections may affect fixture and the long-term osseointegration outcome. Thus chemical composition of a coating at the implant-abutment junction (IAJ) surface is expected to play a key role in preventing bacterial infection. Purpose. In the present study a new antimicrobial polysiloxane coating functionalized with chlorexidine digluconate (PXT) has been tested in an in vitro model. Materials and methods. Twenty implants were coated in the internal chamber with PXT and twenty were used as controls. Results and conclusions. Ten of the coated implants, preliminarily tested against Gram positive and negative bacteria and fungi, showed a complete inactivation of the microbial species after a 15 min contact. On the remaining ten treated implants a series of microbiological tests and PCR analysis, after contamination of the implant external medium, in which the implant have been immersed, with genetic modified Tannerella forsythia (TF) and Porphyromonas Gingivalis (PG), leads to the conclusion that the coating is capable of inactivating the microbial species penetrating the internal of the implant through the implant abutment junction.

The combination of ?-substituted Zn2+ porphyrin dyes and copper-based electrolytes represents a sustainable route for economic and environmentally friendly dye-sensitized solar cells. Remarkably, a new copper electrolyte, [Cu(2-mesityl-1,10-phenanthroline) 2]+/2+, exceeds the performance reached by Co2+/3+ and I-/I3- reference electrolytes.

Transient optical studies, at the nanosecond and femtosecond time scales, have been carried out on three structurally different porphyrin dyes to probe their charge transfer dynamics relevant to spectral sensitization and dye-sensitized solar cell (DSSC) operation. Two of them, showing a ? substitution pattern, were previously reported: ZnB bearing an ethynylphenyl cyanoacrylic acceptor group and ZnBT bearing an additional ?-conjugated dithienylethylene (DTE) chromophore in the acceptor pendant. The new porphyrin ZnMT, showing a donor-acceptor system in 5,15-meso position and the DTE unit as well, is characterized by a smaller HOMO-LUMO energy gap and by a more significant push-pull character which guarantees more intense and red-shifted absorption bands compared to ?-substituted dyes. Besides, the introduction of the DTE unit promotes a remarkable gain in spectral sensitization both in ? and meso positions. We have demonstrated that the population of the absorption manifold resulting from the presence of the additional DTE chromophore leads to charge separation on a time scale of ca. 200 fs, irrespective of either the meso or ? substitution position, resulting in the generation of a long-lived charge-separated state surviving for several microseconds after injection. Thus, dyes equipped with the DTE bridge display the ability to convert photons in the 450-550 nm range, where more common push-pull designs do not show optimal absorption. Further, we have confirmed that ? substitution may represent an effective strategy to combine extended spectral sensitization and optimal charge transfer rates with a synthetic and up-scalable feasibility.

WO3 absorbs light up to 470 nm and when illuminated in the presence of water generates OH• radicals, which promote oxidation of organic pollutants, such as drugs. In the case of WO3 photoanodes, a considerable acceleration (4–5 times) of degradation kinetics is obtained through the application of a 1.5 V potential bias, which is instrumental to optimize the charge separation within the films and to maximize holes transfer rate to the electrolyte. Moreover, after sufficiently long irradiation, complete mineralization of the organics is achieved. Photoelectrocatalysis is observed even in diluted supporting electrolyte conditions, representing the average salinity of natural freshwater samples, demonstrating the practical feasibility of this approach.

A successful general strategy for improving the electron collection efficiency in Dye Sensitized Solar Cells based on common Ru(II) complexes like Z907 and kinetically fast redox mediators based on the [Co(bpy) 3 ] 3+/2+ couples was investigated. The post-treatment of the dyed photoanode with commercially available tri-alkoxy silanes was effective in screening the TiO 2 surface by electron recapture involving Co(III), but, interestingly, silanes endowed with relatively short propyl chains like aminopropyl-triethoxysilane (APTS) and trimethylammoniumpropyl-trimethoxysilane (TMAS) bearing a cationic charge, proved to be more effective than longer and more sterically hindered C16 chains in suppressing the dark current. In the best cases (TMAS and APTS), the siloxane treatment resulted in overall improvements of the cell efficiency of the order of respectively 600% and 500% by comparison with the untreated photoanode based on the Z907 Ru(II) Dye. This approach may represent a viable procedure for improving the electron collection efficiency in cobalt mediated DSSCs even without the use of highly sterically hindered dyes specifically designed to work in conjunction with kinetically fast metal based mediators.

Time-resolved photophysical and photoelectrochemical investigations have been carried out to compare the electron transfer dynamics of a 2-beta-substituted tetraarylporphyrinic dye (ZnB) and a 5,15-meso-disubstituted diarylporphyrinic one (ZnM) at the electrolyte/dye/TiO2 interface in PSSCs. Although the meso push-pull structural arrangement has shown, up to now, to have the best performing architecture for solar cell applications, we have obtained superior energy conversion efficiencies for ZnB (6.1%) rather than for ZnM (3.9%), by using the I-/I-3(-)-based electrolyte. To gain deeper insights about these unexpected results, we have investigated whether the intrinsic structural features of the two different porphyrinic dyes can play a key role on electron transfer processes occurring at the dye-sensitized TiO2 interface. We have found that charge injection yields into TiO2 are quite similar for both dyes and that the regeneration efficiencies by I-, are also comparable and in the range of 75-85%. Moreover, besides injection quantum yields above 80%, identical dye loading, for both ZnB and ZnM, has been evidenced by spectrophotometric measurements on transparent thin TiO2 layers after the same adsorption period. Conversely, major differences have emerged by DC and AC (electrochemical impedance spectroscopy) photoelectrochemical investigations, pointing out a slower charge recombination rate when ZnB is adsorbed on TiO2. This may result from its more sterically hindered macrocyclic core which, besides guaranteeing a decrease of pi-staking aggregation of the dye, promotes a superior shielding of the TiO2 surface against charge recombination involving oxidized species of the electrolyte.

In the version of this Article originally published, in the graphical abstract the y-axis units of the plot read 'mA cm-2', but should have read 'μA cm-2'. Additionally, an erroneous gap appeared in the red trace. These errors have now been corrected.

The electrochemical properties of both pristine single walled carbon nanohorns (SWCNHS) and their chemically oxidized form (ox-SWCNHS) spray coated onto fluorine doped SnO2 (FTO) were investigated in the framework of the fabrication of cobalt based transparent dye sensitized solar cells (DSSCs). These new nanocarbon substrates, evaluated in conjunction with the Co(bpy)3(2+/3+) (bpy = 2,2'-bipyridine) redox mediator, are endowed with excellent electrocatalytic properties, ease of fabrication, and very promising stability and display a great potential for replacing the best noble metal and conductive polymer catalytic materials in the building of semitransparent counter electrodes in new generation photoelectrochemical devices.

Iron (III) oxide applications as anodic material in electrocatalysis and photoelectrochemical cells are currently limited by its poor electric properties. To overcome these issues, doping has been applied with some success and high-temperature (800 °C) treatment on fluorine doped tin oxide substrates, leading to tin-doping, is now a widely employed procedure to activate hematite anodes. In this paper we undertake a systematic investigation of the effects of tin doping on the structural, optical and electrochemical properties of hematite thin films, focusing on the anodic performance towards water splitting. To isolate the effect of doping from those of morphology and crystallinity, we devise a fabrication method based on radio-frequency magnetron sputtering yielding crystalline hematite at room temperature, thus enhancing the compatibility towards substrates and the potential for application. Doping in the range 1-12% (atomic) induces lattice distortion with cell volume increase and a substantial extension of the visible absorption range due to a band-gap narrowing of about 0.45 eV for the highest doping level. The electrode metrics are greatly improved, with a shift of up to 60 mV towards less positive overpotentials and Tafel slopes about the half of the original value. The best performance is found for a 6.2 at. % doping, with η = 441 mV (at j = 1 mA/cm2) and a 48 mV/dec Tafel slope, in line with current state-of-the-art results reported for amorphous iron based catalysts. In our case tin doping leads to improved conductivity and to a decreased (up to 1 order of magnitude) interfacial charge transfer resistance, as revealed by electrochemical impedance spectroscopy.

The photoanodic response of two different types of nanocrystalline WO3 electrodes prepared by following either the sol gel approach or the accelerated anodization route was explored in sulfate containing electrolytes with the aim of exploring the mechanism of charge separation at WO3/electrolyte interfaces. Combined evidence by electrochemical impedance spectroscopy and transient absorption spectroscopy indicates that hole transfer occurs through the valence band and that, under applied bias, the voltage drop involves predominantly the space charge layer of the semiconductor, controlling the photocurrent via potential-induced variations of hole density at the surface of WO3. OH radicals were found among the primary water oxidation intermediates, and are partly responsible for mediated back recombination. The generation of hydroxyl radicals suggests, however, that WO3 based materials can find promising applications in environmental photoremediation under visible light, promoting (OH)-O-center dot mediated oxidation of impervious contaminants. In principle, the removal of (OH)-O-center dot by organic scavengers will also optimize the photocurrent generation in photoelectrochemical cells where the generation of hydrogen can be coupled to environmental decontamination.

A tetracoordinated redox couple, made by [Cu(2-mesityl-4,7-dimethyl-1,10-phenanthroline)2][PF6], 1, and its Cu(II) form [Cu(2-mesityl-4,7-dimethyl-1,10-phenanthroline)2][PF6]2, 2, has been synthesized, and its electrochemical and photochemical features have been investigated and compared with those of a previously published Cu(2+)/Cu(+) redox shuttle, namely, [Cu(2,9-dimethyl-1,10-phenanthroline)2][PF6], 3, and its pentacoordinated oxidized form [Cu(2,9-dimethyl-1,10-phenanthroline)2Cl][PF6], 4. The detrimental effect of the fifth Cl(-) ancillary ligand on the charge transfer kinetics of the redox shuttles has been exhaustively demonstrated. Appropriately balanced Cu-based electrolytes have been then formulated and tested in dye solar cells in combination with a π-extended benzothiadiazole dye. The bis-phenanthroline Cu-complexes, 1 and 2, have been found to provide an overall 4.4% solar energy conversion efficiency, which is more than twice that of the literature benchmark couple, 3 and 4, employing a Cl-coordinated oxidized species and even comparable with the performances of a I(-)/I3(-) electrolyte of analogous concentration. A fast counter-electrode reaction, due to the excellent electrochemical reversibility of 2, and a high electron collection efficiency, allowed through the efficient dye regeneration kinetics exerted by 1, represents two major characteristics of these copper-based electron mediators and may constitute a pivotal step toward the development of a next generation of copper-based efficient iodine-free redox shuttles.

Integrated absorber/electrocatalyst schemes are increasingly adopted in the design of photoelectrodes for photoelectrochemical cells because they can take advantage of separately optimized components. Such schemes also lead to the emergence of novel challenges, among which parasitic light absorption and the nature of the absorber/catalyst junction features prominently. By taking advantage of the versatility of pulsed-laser deposition technique, we fabricated a porous iron(III) oxide nanoparticle-assembled coating that is both transparent to visible light and active as an electrocatalyst for water oxidation. Compared to a compact morphology, the porous catalyst used to functionalize crystalline hematite photoanodes exhibits a superior photoresponse, resulting in a drastic lowering of the photocurrent overpotential (about 200 mV) and a concomitant 5-fold increase in photocurrents at 1.23 V versus reversible hydrogen electrode. Photoelectrochemical impedance spectroscopy indicated a large increase in trapped surface hole capacitance coupled with a decreased charge transfer resistance, consistent with the possible formation of an adaptive junction between the absorber and the porous nanostructured catalyst. The observed effect is among the most prominent reported for the coupling of an electrocatalyst with a thin layer absorber.