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A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H2O2 from H2 and O2. These catalysts were characterized by nitrogen adsorption-desorption, low and wide-angle X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), elemental mapping and energy-dispersive X-ray (EDX) methods. It was found that the particle size, electronic interactions, morphology, and textural properties of these catalysts as well as their catalytic activity in the reaction of H2 with O2 were affected by Co addition and different calcination temperatures. Also, the results showed that while the H2O2 selectivity depends on Pd2+ species, the H2 conversion is related to Pd0 active sites. Among these catalysts, CoPd/KIT-6 calcined at 350 °C (CoPd/KIT-350 catalyst) showed the best catalytic activity with 50 % of H2O2 selectivity and 51 % conversion of H2.

Transition-metal dichalcogenide (TMD) nano-sheets have become an intensively investigated topic in the field of 2D nanomaterials, especially due to the direct semiconductor nature, and the broken inversion symmetry in the odd-layer number, of some of their family members. These properties make TMDs attractive for different technological applications such as photovoltaics, optoelectronics, valleytronics, and hydrogen evolu-tion reactions. Among them, MoX2 (X = S and Se) are turned to direct gap when their thickness is thinned down to monolayer, and thus, efforts toward obtaining large-scale monolayer TMDs are crucial for technological applications. Colloidal synthesis of TMDs has been developed in recent years, as it provides a cost-efficient and scalable way to produce few-layer TMDs having homogeneous size and thickness, yet obtaining a monolayer has proven challenging. Here, we present a method for the colloidal synthesis of mono-and few-layer MoX2 (X = S and Se) using elemental chalcogenide and metal chloride as precursors. Using a synthesis with slow injection of the MoCl5 precursor under a nitrogen atmosphere, and optimizing the synthesis parameters with a design of experiments approach, we obtained a MoX2 sample with the semiconducting (1H) phase and optical band gaps of 1.96 eV for H-1-MoS2 and 1.67 eV for 1H-MoSe2, respectively, consistent with a large monolayer yield in the ensemble. Both display photoluminescence at cryogenic and room temperature, paving the way for optical spectroscopy studies and photonic applications of colloidal TMD nanosheets.

This research aims to define a protocol for nisin adsorption onto Ti6Al4V- Extra Low Interstitial content (ELI) alloy to reduce the risk of peri-implant infections. The substrate is, first, etched to get a nanotextured surface with a high density of acidic hydroxyl groups and then functionalized with the antimicrobial peptide nisin. Nisin adsorption is performed at different pH values, in the range of 5–7. The nisin release in inorganic solutions mimicking physiological or pro-inflammatory conditions is tested. The surfaces are characterized by profilometry, SEM/EDS, contact angle and surface free energy measurements, zeta potential titrations, DLS, XPS, and UV–visible spectroscopy. Effective surface adsorption was achieved and maximized at pH 6. The coated surface has high surface energy suitable for tissue integration and it releases nisin in a time longer than 1 day. As a confirmation of the antibacterial properties due to the nisin adsorption, specimens were incubated with Staphylococcus aureus, whose metabolic activity was reduced by ≈ 70% in comparison to the untreated control, and the number of viable adhered colonies was ≈ 6 times reduced. In conclusion, coupling of nisin to a chemically treated titanium surface is promising for a bioactive and antibacterial surface for tissue integration.

Improving the perovskite/electron-transporting layer (ETL) interface is a crucial task to boost the performance of perovskite solar cells (PSCs).

Invited for this month cover is the group of Teresa Gatti at the Justus Liebig University (JLU) in Giessen, Germany, the group of Federico Bella at Politecnico di Torino (POLITO), Italy, and the group of Francesco Lamberti at the University of Padova (UNIPD), also in Italy. The image shows how waste tires can be converted in a conductive carbon powder that undergoes a green processing step to produce carbon electrodes for lead-free perovskite solar cells. Similar devices can be employed to harvest indoor light in order to power the Internet of Things (IoT) ecosystem. The Research Article itself is available at 10.1002/cssc.202201590.

We show how, in the synthesis of yellow-emissive Bi-doped Cs

Bioactive glasses (BGs) are promising for bone tissue regeneration. BG composition can be tailored, according to the application of interest, and/or functionalized with organic molecules/biomolecules to improve their per- formances. However, despite the wide knowledge concerning BGs, their interaction with proteins, fundamental for controlling the fate of the implant, has not been deeply investigated yet. Controlling or predicting protein adsorption requires a full understanding of the materials surface physico-chemical properties. In this work, four different BGs (S53P4, B25, SCNB, PhGlass) were surface-modified by four different treatments: 72 h-soaking in TRIS, 72 h soaking in simulated body fluid, APTES grafting and quaternized APTES grafting. The surfaces were then characterized both untreated and after each treatment by contact angle, zeta potential analysis, X-ray photoelectron spectroscopy, Fourier Transform InfraRed–Attenuated Total Reflectance spectroscopy and Scan- ning Electron Microscopy and Energy Dispersive Spectroscopy. Inductively Coupled Plasma – Optical Emission Spectrometry was then performed to investigate the ion leaching. The aim of this study (Part I) is the physico- chemical characterization of BGs as a function of the implemented treatments, aiming to better understand how the superficial properties are successively affecting protein adsorption. Protein adsorption on untreated and treated BGs will be discussed in a following manuscript (Part II).&nbsp

Recent years have seen the wide diffusion of composite materials in many manufacturing fields and the rapid evolution of additive manufacturing. Lately, these technologies have been combined practically allowing the fabrication of continuous-fiber reinforced polymer parts via 3D-printing. This topic is gaining attention both in the research community and among industrial users. Because of their novelty, such manufacturing methods are, however, still not thoroughly understood, and their performance limits have not yet been fully characterized. This study aims at analyzing the mechanical resistance of components made with continuous carbon fiber (CCF) thermoplastic materials by means of fused filament fabrication (FFF), focusing on the influence of the fiber orientation on such properties. In particular, both the tensile and the bending characteristics are evaluated according to the relative test standards, in specimens with both unidirectional and mixed-isotropic configurations. The experimental findings are compared with a set of reference specimens made with a base polymer filled with chopped “short” carbon fibers, allowing one to appreciate the advantages or limitations of the different fiber arrangements.

The most developed approaches for the synthesis of InAs nanocrystals (NCs) rely on pyrophoric, toxic, and not readily available tris-trimethylsilyl (or tris-trimethylgermil) arsine precursors. Less toxic and commercially available chemicals, such as tris(dimethylamino)arsine, have recently emerged as alternative As precursors. Nevertheless, InAs NCs made with such compounds need to be further optimized in terms of size distribution and optical properties in order to meet the standard reached with tris-trimethylsilyl arsine. To this aim, in this work we investigated the role of ZnCl

Advancements in electrochemical double-layer capacitor (EDLC) technology require the concomitant use of novel efficient electrode materials and viable electrode manufacturing methods. Cost-effectiveness, scalability and sustainability are key-drivers for fulfilling product development chain accepted by worldwide legislations. Herein, we report a scalable and sprayable “green” electrode material-based ink based on activated carbon and single-/few-layer graphene (SLG/FLG) flakes. We show that, contrary to commercial reduced graphene oxide, defect-free and flat SLG/FLG flakes reduce the friction of ions over the electrode films, while spray coating deposition of our ink maximises the electrolyte accessibility to the electrode surface area. Sprayed SLG/FLG flakes-based EDLCs display superior rate capability performance (e.g., specific energies of 31.5, 23.7 and 12.5 Wh kg−1 at specific powers of 150, 7500 and 30000 W kg−1, respectively) compared to both SLG/FLG flakes-free devices and commercial-like EDLCs produced by slurry-coating method. The use of SLG/FLG flakes enables our sprayed EDLCs to operate in a wide range of temperature (−40/+100°C) compatible with ionic liquid/organic solvent-based electrolytes, overcoming the specific power limits of AC-based EDLCs. A prototype EDLCs stack consisting of multiple large-area EDLCs, each one displaying a capacitance of 25 F, demonstrates the industrial potential of our technology.

Hybrid quantum wells are electronic structures where charge carriers are confined along stacked inorganic planes, separated by insulating organic moieties. 2D quantum-confined hybrid materials are of great interest from a solid-state physics standpoint because of the rich many-body phenomena they host, their tunability and easy synthesis, allowing the creation of material libraries. In addition, from a technological point of view, 2D hybrids are promising candidates for efficient, tunable, low-cost materials impacting a broad range of optoelectronic devices. Different approaches and materials have, therefore, been investigated, with the notable example of 2D metal halide hybrid perovskites. Despite the remarkable properties of such materials, the presence of toxic elements like lead is not desirable in applications and their ionic lattices may represent a limiting factor for stability under operating conditions. Therefore, non-ionic 2D materials made with non-toxic elements are preferable. In order to expand the library of possible hybrid quantum well materials, herein, we consider an alternative platform based on non-toxic, self-assembled, metal-organic chalcogenides. While the optical properties have been recently explored and some unique excitonic characters highlighted, photo-generation of carriers and their transport in these lamellar inorganic/organic nanostructures and critical optoelectronic aspects remain totally unexplored. We hereby report the first investigation on the electrical properties of the air-stable [AgSePh]∞ 2D coordination polymer in the form of nanocrystal (NC) films readily synthesized in situ and at low temperature, compatible with flexible plastic substrates. The wavelength-dependent photo-response of the NC films suggests the possible use of this material as a near-UV photodetector. We therefore built a lateral photo-detector, achieving a sensitivity of 0.8 A W-1 at 370 nm, thanks to a photoconduction mechanism, and a cut-off frequency of ∼400 Hz, and validated its reliability as an air-stable UV detector on flexible substrates.

Hollow structures made of nanoscale building blocks are of great interest as catalysts for electrochemical water splitting. Here we report a solution-phase synthesis of yolk–shell Co3O4/Co1−xRuxO2 microspheres (MSs) having a shell made of Co1−xRuxO2 nanorods and the core of Co3O4. Benefiting from the peculiar morphology and the synergy between the different materials present in the MSs, the latter exhibit enhanced electrochemical oxygen evolution activity and long-term stability in acidic media. The catalyst achieves a catalytic current density of 10 mA cm−2 at an overpotential of only 240 mV, a small Tafel slope of 70 mV dec−1, and a high mass activity of 600 A g−1 and maintains its activity throughout a 24 h chronopotentiometry tests at constant current densities of 10 and 20 mA cm−2.

Cu2ZnSn(S,Se)4 (CZTSSe) are benign and low-cost materials, overcoming the limitations of toxicity and high costs of other semiconductors such as CuInGa(S,Se)2, cadmium and lead chalcogenides, and Pb-based perovskites widely used in photovoltaic and thermoelectric applications. In order to shed light on the formation mechanism of CZTS nanoparticles using anisole as the solvent, oleylamine as the organic ligand, carbon disulphide as the sulphur source and Zn(NO3)2·6H2O as the Zn(II) precursor, we follow the conversion of binary sulphides formed in situ under solvothermal conditions into quaternary phases. Besides a careful microstructural characterization of the as-synthesized materials by X-ray diffraction (XRD), Raman spectroscopy, electron microscopy (TEM and HRTEM) and energy dispersive X-ray (EDX) spectroscopy at micron- and nano-scale, we study the evolution of particle surface properties by X-ray-photoelectron spectroscopy (XPS). The results show that CZTS particles form already during the early stages of the reaction, most probably through a nucleation and growth mechanism. In parallel, a comparably slower growth mechanism is observed that involves recrystallization between the binary phases, without evidence of ternary phase formation.

Aim: To realize and characterize a new generation of keratin-coated gold nanoparticles (Ker-AuNPs) as highly efficient photosensitive nanosized therapeutics for plasmonic photothermal (PPT) therapy. Materials & methods: The chemical, physical, morphological and photothermal properties of Ker-AuNPs are investigated using dynamic light scattering, ζ-potential, UV–Visible, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy and high-resolution thermography. In vitro experiments are performed on a human glioblastoma cell line (i.e., U87-MG), using viability assays, transmission electron microscopy, fluorescence microscopy, cytometric analyses and PPT experiments. Results: Experiments confirm the excellent biocompatibility of Ker-AuNPs, their efficient cellular uptake and localized photothermal heating capabilities. Conclusion: The reported structural and functional properties pointed out these Ker-AuNPs as a promising new tool in the field of biocompatible photothermal agents for PPT treatments against cancer-related diseases.

Various strategies have been proposed to engineer the band gap of metal halide perovskite nanocrystals (NCs) while preserving their structure and composition and thus ensuring spectral stability of the emission color. An aspect that has only been marginally investigated is how the type of surface passivation influences the structural/color stability of AMX3 perovskite NCs composed of two different M2+ cations. Here, we report the synthesis of blue-emitting Cs-oleate capped CsCdxPb1-xBr3 NCs, which exhibit a cubic perovskite phase containing also Cd-rich domains of Ruddlesden-Popper phases (RP- phases). The RP domains spontaneously transforms into pure orthorhombic perovskite ones upon NC ageing and the emission color of the NCs shifts from blue to green over days. On the other hand, post-synthesis ligand exchange with various Cs-carboxylate or ammonium bromide salts, right after NC synthesis, provides monocrystalline NCs with cubic phase, highlighting the metastability of the RP domains. When the NCs are treated with Cs-carboxylates (including Cs-oleate), most of the Cd2+ ions are expelled from the NCs, the NCs’ phase evolves from cubic to orthorhombic and their emission color changes from blue to green. Instead, when the NCs are coated with ammonium bromides, the loss of Cd2+ ions is suppressed and the NCs tend to retain their blue emission (both in colloidal dispersions and in electroluminescent devices), as well as their cubic phase, over time. The improved compositional and structural stability in these latter cases is ascribed to the saturation of surface vacancies, which may act as channels for the expulsion of Cd2+ ions from the NCs.

The search for materials substituting toxic lead in metal halide perovskites has recently placed emphasis on the Cs2AgBiBr6 double perovskite as a possible candidate. The poor light-emissive features of this species, mainly associated to the indirect nature of the band gap and the strongly bound exciton, however, currently make it unsuitable for solid-state lighting applications. Doping with lanthanides is an established strategy to implement luminescence in poorly emissive materials, with the additional advantage of tuning the wavelength of emission independently from the host band structure. We discuss here the impact of Eu- and Yb-doping on the absorption and emission properties of Cs2AgBiBr6 polycrystalline thin films, obtained from solution-processing of hydrothermally synthesized bulk crystalline powders, by combining experiments and density functional theory calculations. Eu(III) incorporation does not lead to the characteristic 5D0→7F2 emission feature at 2 eV, while only a weak sub band-gap radiative emission ascribed to a trap-assisted recombination process is reported. On the other hand, we demonstrate that Yb(III) incorporated in the bulk double perovskite leads to an intense and exclusive photoluminescence emission in the near-infrared (NIR) from thin films, as a result of the efficient sensitization of the lanthanide centered 2F5/2→2F7/2 transition, with favorable mid-gap energetic position. Yb-doping may be thus exploited for the future development of stable and sustainable perovskite NIR-light emitters.

Metallic two-dimensional transition-metal dichalcogenides (TMDs) of the group 5 metals are emerging as catalysts for an efficient hydrogen evolution reaction (HER). The HER activity of the group 5 TMDs originates from the unsaturated chalcogen edges and the highly active surface basal planes, whereas the HER activity of the widely studied group 6 TMDs originates solely from the chalcogen- or metal-unsaturated edges. However, the batch production of such nanomaterials and their scalable processing into high-performance electrocatalysts is still challenging. Herein, we report the liquid-phase exfoliation of the 2H-TaS2 crystals by using 2-propanol to produce single/few-layer (1H/2H) flakes, which are afterward deposited as catalytic films. A thermal treatment-aided texturization of the catalytic films is used to increase their porosity, promoting the ion access to the basal planes of the flakes, as well as the number of catalytic edges of the flakes. The hybridization of the H-TaS2 flakes and H-TaSe2 flakes tunes the Gibbs free energy of the adsorbed atomic hydrogen onto the H-TaS2 basal planes to the optimal thermo-neutral value. In 0.5 M H2SO4, the heterogeneous catalysts exhibit a low overpotential (versus RHE, reversible hydrogen electrode) at the cathodic current of 10 mA cm-2 (η10) of 120 mV and high mass activity of 314 A g-1 at an overpotential of 200 mV. In 1 M KOH, they show a η10 of 230 mV and a mass activity of 220 A g-1 at an overpotential of 300 mV. Our results provide new insight into the usage of the metallic group 5 TMDs for the HER through scalable material preparation and electrode processing.

Oxidized single walled carbon nanohorns (ox-SWCNH) were electrodeposited onto gold microelectrode arrays in conjunction with poly(3,4-ethylenedioxythiophene) (PEDOT) and polystirenesulfonate (PSS), and the properties of the new composite material for neural recording and stimulation were assessed. PEDOT/ox-SWCNH composites were compared with films prepared with one of the most notorious carbonaceous material in this field, the oxidized multi-walled Carbon Nanotubes (ox-MWCNT). The PEDOT/ox-SWCNH exhibited superior charge transfer capability, reflecting greater electroactive surface, as confirmed by SEM and EIS characterizations. As a consequence, a charge injection limit of 11.6mC/cm⁠2 was observed for the new composite, which is higher than the one of PEDOT/ox-MWCNT (8.7mC/cm⁠2). Having confirmed comparable neural recording performance, the PEDOT/ ox-SWCNH composite results very promising for improving therapeutic electrical stimulation in the central and peripheral nervous systems.

Here we present a colloidal approach to synthesize bismuth chalcohalide nanocrystals (BiEX NCs, in which E=S, Se and X=Cl, Br, I). Our method yields orthorhombic elongated BiEX NCs, with BiSCl crystallizing in a previously unknown polymorph. The BiEX NCs display a composition-dependent band gap spanning the visible spectral range and absorption coefficients exceeding 105 cm-1 . The BiEX NCs show chemical stability at standard laboratory conditions and form colloidal inks in different solvents. These features enable the solution processing of the NCs into robust solid films yielding stable photoelectrochemical current densities under solar-simulated irradiation. Overall, our versatile synthetic protocol may prove valuable in accessing colloidal metal chalcohalide nanomaterials at large and contributes to establish metal chalcohalides as a promising complement to metal chalcogenides and halides for applied nanotechnology.

We demonstrate efficient, stable, and fully RoHS-compliant near-infrared (NIR) light-emitting diodes (LEDs) based on InAs/ZnSe quantum dots (QDs) synthesized by employing a commercially available amino-As precursor. They have a record external quantum efficiency of 5.5% at 947 nm and an operational lifetime of ∼32 h before reaching 50% of their initial luminance. Our findings offer a new solution for developing RoHS-compliant light-emitting technologies based on Pb-free colloidal QDs.

Cu2ZnSnS4 and Cu2ZnSnSe4 (CZTS and CZTSe, respectively) and their mixed chalcogenide phase Cu2ZnSnSxSe4-x (CZTSS(e)) are benign and cheap photovoltaic absorber materials that represent a valuable alternative to the more expensive chalcogenide systems: i.e., Cu(In,Ga)SS(e)2 (CIGSS(e)). One of the main challenges related to the fabrication of CZTS(e) layers is the control over both the crystalline phase (tetragonal, cubic, or hexagonal) and the formation of binary (MS, M = Cu(II), Zn(II), Sn(II); M'2-xS, M'= Cu(I), x = 0, 0.2; M″S2, M″ = Sn(IV)) and ternary products (CTS phases, Cu2SnS3, Cu3SnS4) that hinder the performance of the corresponding devices. In the present work, we rationalize the formation pathway of the CZTS phase through binary and ternary products when salt precursors with chloride and acetate as counteranions, respectively, are employed. The results show that the counteranions have a remarkable influence on the formation pathway of CZTS nanoparticles. The use of chloride precursors leads to the predominant formation of CTSs ternary phases (Cu2SnS3, Cu3SnS4), whereas the formation of the CZTS phase is not observed even for higher temperature and longer reaction time (250 °C, 24 h). In the case of acetates the copresence of CZTS as the main product, together with binary and ternary phases, is observed in the early stages of the reaction even at lower temperature and shorter reaction time (200 °C, 2 h), while when the reaction time and temperature are increased, only the CZTS phase is observed. In addition to a careful microstructural characterization of the as-synthesized materials by Raman spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM), we shed light on the reactivity among the metal precursors, the organic ligand oleylamine, and the sulfur precursor carbon disulfide (CS2) by 13C nuclear magnetic resonance (13C NMR) and investigate in depth the effect on particle surfaces by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and XPS. A rationale for the formation pathway of CZTS nanoparticles is proposed and supported by experimental evidence.

Pt nanoparticles deposited on mesoporous carbon (Pt/C) represent a benchmark catalyst for the hydrogen evolution reaction (HER) in both acid and alkaline conditions. However, it shows an order of magnitude lower activity under alkaline media compared to acid media. Moreover, the activity of this catalyst decreases rapidly under operational conditions due to both migration and aggregation of the metal particles, leading to a rapid decline in the number of active sites. We show here a Cu and Ru-based catalyst fabricated by slow electrodeposition of Ru onto a nanostructured Cu layer grown, in turn, on the top of a Ti substrate. Our catalyst has a high and stable HER activity, outperforming the benchmark Pt/C catalyst under alkaline conditions. The high activity and prolonged stability are attributed to the peculiar structure of our electrode, in which Cu nanoplates are directly attached perpendicular to the Ti substrate, providing a high surface area support onto which Ru nanocrystals are bound. This makes the Cu–Ru/Ti electrode one of the most active (−10 mA cm2 of HER current at only −23 mV overpotential) and stable electrocatalysts (no activity degradation for 100 h at −0.2 V) reported to date for the alkaline hydrogen evolution reaction.

Focused ion beam (FIB) has recently been used to tune the optical properties of lead halide perovskites (LHPs), opening an interesting avenue for applications in optoelectronic devices. However, it has remained an open question to date whether FIB can be used to locally enhance the photoluminescence (PL) of LHPs. In this work we irradiate MAPbBr3 (MA = methylammonium) single crystals with a high energy micron-sized ion probe of different ionic masses (3 MeV He+, 12.5 MeV Br5+, and 20 MeV I7+) and study the PL as a function of the damage induced by the ion beam. We find that at low damage levels the PL is enhanced about six times with respect to the pristine material, while increasing the damage level produces a progressive PL decrease, and, above a threshold, the PL is finally quenched below the value of the pristine crystal. We attribute this behavior to the interaction of free carriers with irradiation induced surface defects: at low damage levels the migration of carriers toward the bulk is inhibited via trapping–detrapping events at surface defects, allowing their radiative recombination near the surface; at higher damage, though, the probability for non-radiative recombination increases and gradually becomes dominant. We thus present a method to locally increase the PL of bulk LHP, which could be applied in a wide range of fields, such as highly sensitive ion beam detection or future optoelectronic device design.

Light-emitting diodes (LEDs) based on lead halide perovskite (LHP) nanocrystals (NCs) have received plenty of attention in recent years, owing to their excellent colour purity and easily tunable emission colour. However, the efficiency of LHP NC-based LEDs generally lags behind that of polycrystalline LHP thin-film-based LEDs, especially for blue LEDs. In this work, we synthesize bromide-based LHP NCs, treat them with CuCl2 in a simple post-processing way, and apply the obtained NCs for the fabrication of sky-blue LEDs. The results of device characterization indicate a significant impact of the solvent used in the NC dispersion on the efficiency and spectral stability of the LEDs. The champion device, based on NCs with optimized ligands, results in an external quantum efficiency (EQE) of 5.02% and a luminance of 130 cd m−2 at the maximum EQE. This work provides a novel and promising way for the fabrication of highly efficient LHP NC-based blue LEDs.

Perovskite solar cells (PSCs) are currently the leading thin-film photovoltaic technology owing to their high power conversion efficiency (PCE), as well as their low-cost and facile manufacturing process. Two-dimensional (2D) materials have been reported to improve both the PCE and the stability of PSCs when incorporated across the device's layered configuration. Hereby, a two-fold engineering approach is implemented in inverted PSCs by using ultra-thin Bi2Te3 flakes, i.e.: (1) to dope the electron transport layer (ETL) and (2) to form a protective interlayer above the ETL. Thorough steady-state and time-resolved transport analyses reveal that our first engineering approach improves the electron extraction rate and thus the overall PCE (+6.6% vs. reference cells), as a result of the favourable energy level alignment between the perovskite, the ETL and the cathode. Moreover, the Bi2Te3 interlayer, through the second engineering approach, facilitates further the electron transport and in addition protects the underlying structure against chemical instability effects, leading to enhanced device performance and stability. By combining the two engineering approaches, our optimised PSCs reach a PCE up to 19.46% (+15.2% vs. reference cells) and retain more than 80% of their initial PCE, after the burn-in phase, over 1100 h under continous 1 sun illumination. These performances are among the highest reported in the literature for inverted PSCs.

Recent studies on anatase TiO2 have demonstrated its capability of performing as an anode material for sodium-ion batteries (SIBs) even though, due to poor conductivity, realistic applications have not yet been foreseen. In order to try to address this issue, herein, we shall introduce a cost effective and facile route based on the co-precipitation method for the synthesis of Mo-doped anatase TiO2 nanoparticles with AlF3 surface coating. The electrochemical measurements demonstrate that the Mo-doped anatase TiO2 nanoparticles deliver an ∼40% enhanced reversible capacity compared to pristine TiO2 (139.8 vs. 100.7 mA h g−1 at 0.1 C after 50 cycles) due to an improved electronic/ionic conductivity. Furthermore, upon AlF3 coating, the overall system can deliver a much higher reversible capacity of 178.9 mA h g−1 (∼80% increase with respect to pristine TiO2) with good cycling stability and excellent rate capabilities of up to 10 C. The experimental results indicate that the AlF3 surface coating could indeed effectively reduce the solid electrolyte interfacial resistance, enhance the electrochemical reactivity at the surface/interface region, and lower the polarization during cycling. The improved performance achieved using a cost-effective fabrication approach makes the dually modified anatase TiO2 a promising anode material for high-performance SIBs.

Poly(3,4-ethylentedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most studied materials for organic bioelectronics, supercapacitors and organic photovoltaics. Its low impedance is ascribed to the so-called volumetric capacitance, a property that phenomenologically correlates the capacitive coupling/charge storage in devices to the PEDOT:PSS volume/thickness. Here we investigate the correlation between the capacitance and the electroactive surface area (ESA) for large-volume spin-cast PEDOT:PSS electrodes. We measure the capacitance with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and characterize the surface morphology by atomic force microscopy and X-ray photoelectron spectroscopy. Capacitance of PEDOT:PSS films scales with volume up to ~5 × 106 ?m3 but is saturated at larger volumes. This scaling behavior is paralleled by the scaling of the ESA, hence the ratio between the effective capacitance and ESA remains constant across the whole data set, thus showing that the specific areal capacitance is indeed the relevant material property of PEDOT:PSS. EIS data fit supports the experimental evidence obtained by CV, further revealing that the diffusion time constant is also saturated at high volumes. This supports the scenario where the effective capacitance relates to the ion accessible ESA, and shows that the saturation of the capacitance arises from a change of ion penetration from a diffusive (at small volumes) to a non-diffusive regime at large volumes.

The photocatalytic activity of TiO2 polymorphs has been frequently debated in literature. Numerous studies reported that rutile TiO2 exhibits low photocatalytic activity, and it is generally accepted that rutile has lower photoactivity than the anatase phase. Herein, we studied the photocatalytic activity of phase-pure rutile TiO2 nanoparticles prepared via microwave-assisted hydrothermal method (MW-R NPs). The syntheses were performed with relatively short reaction time (1−3h) at 180 °C using a microwave digestion system. The samples were characterized in detail and then tested in the photodegradation of methyl orange (MO). We demonstrate that the photodegradation of MO with MW-R NPs is highly efficient in the presence of H2O2. By employing 4.4 mM H2O2, ~90% of total decolorization was achieved after 2 min of UV-A irradiation. At the same experimental conditions, MO degradation with Degussa P25 TiO2 was only ~7%. The superior photoactivity of MW-R NPs was related to the effective photogeneration of O2•− radicals as revealed by EPR investigation. These rutile nanoparticles are excellent photocatalysts in the presence of H2O2, signifying that this oxygen source react easily with the photogenerated holes on the MW-R NPs, and thus the interfacial charge transfer lead to the formation of a large amount of O2•− radicals.