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Exacerbation of climate change has highlighted the need for new environmentally-friendly energy sources. Fuel cells, which are devices capable of extracting electricity directly from internal chemical reactions, represent one promising concept that allows electricity generation without burning fossil fuels. Direct methanol fuel cells are one of the most popular types, and they use methanol as the fuel for electricity production. However, the current lack of suitable electrocatalytic materials limits the application of such devices on an industrial scale. This report presents a simple, one-step method for the preparation of electrocatalytic materials for methanol oxidation. The developed composite materials contain two metals (nickel and cobalt), which both exhibit catalytic properties relevant for methanol electrooxidation, and graphene, which is a carbon nanomaterial that promotes facile charge transfer and enhanced material dispersion. The tested electrodes were prepared using an electrochemical deposition process, which allowed easy control of the process conditions, such as current density, and thus easy manipulation of the final material's properties. Following this process, stable electroactive materials were prepared, and the optimal results were obtained with the electrode prepared with a current density of 3.5 A dm−2 for 15 min: this electrode had a peak current density of 15.82 mA cm−2 in 1 M KOH +1 M methanol solution.

Herein, we present a new strategy for the development of efficient heavy-atom free singlet oxygen photosensitizers based on rigid borafluorene scaffolds. Physicochemical properties of borafluorene complexes can be easily tuned through the choice of ligand, thus allowing exploration of numerous organoboron structures as potent 1O2 sensitizers. The singlet oxygen generation quantum yields of studied complexes vary in the range of 0.55-0.78. Theoretical calculations reveal that the introduction of the borafluorene moiety is crucial for the stabilization of a singlet charge transfer state, while intersystem crossing to a local triplet state is facilitated by orthogonal donor-acceptor molecular architecture. Our study shows that quantitative oxidation of selected organic substrates can be achieved in 20-120 min of irradiation with only 0.05 mol % loading of a photocatalyst.

This paper describes a formation of hybrid coatings on a Ti–2Ta–3Zr–36Nb surface. This is accomplished by plasma electrolytic oxidation and a dip-coating technique with poly(adipic anhydride) ((C6H8O3)n) that is loaded with drugs: amoxicillin (C16H19N3O5S), cefazolin (C14H14N8O4S3) or vancomycin (C66H75Cl2N9O24 · xHCl). The characteristic microstructure of the polymer was evaluated using scanning electron microscopy and confocal microscopy. Depending on the surface treatment, the surface roughness varied (between 1.53 μm and 2.06 μm), and the wettability was change with the over of time. X-ray photoelectron spectroscopy analysis showed that the oxide layer did not affect the polymer layer or loaded drugs. However, the drugs lose their stability in a phosphate-buffered saline solution after 6.5 h of exposure, and its decrease was greater than 7% (HPLC analysis). The stability, drug release and concentration of the drug loaded into the material were precisely analyzed by high-performance liquid chromatography. The results correlated with the degradation of the polymer in which the addition of drugs caused the percent of degraded polymer to be between 35.5% and 49.4% after 1 h of material immersion, depending on the mass of the loaded drug and various biological responses that were obtained. However, all of the coatings were cytocompatible with MG-63 osteoblast-like cells. The drug concentrations released from the coatings were sufficient to inhibit adhesion of reference and clinical bacterial strains (S. aureus). The coatings with amoxicillin showed the best results in the bacterial inhibition zone, whereas coatings with cefazolin inhibited adhesion of the above bacteria on the surface., Graphical abstract Image 1, Highlights • Hybrid layers containing fast degradable poly(adipic anhydride) (PADA) were performed. • Drugs stability, concentration of released and loaded drugs were evaluated using HPLC. • Adhesion of S. aureus clinical and reference strains confirmed the antibaterial properties. • Performed hybrid layers were cytocompatible (MG-63 tests).

We report the use of efficient visible-light sensitive allyl (QA) and epoxidized (QE) quinizarin derivatives as photoinitiating systems when combined with an appropriate electron donor (methyldiethanol amine, MDEA), an electron acceptor (iodonium salt, Iod), or a H donor (thiol derivative), for free-radical photopolymerization (FRP), cationic photopolymerization (CP), and a thiol–ene process. These systems have demonstrated excellent initiating properties under air or in laminated conditions under visible-light irradiation (LEDs@405, 455, and 470 nm or Xe lamp) for FRP, CP, or the thiol–ene process and appear more efficient than the well-known camphorquinone-based photoinitiating systems. As highlighted by electron paramagnetic resonance (EPR) and laser flash photolysis experiments, QA (or QE) acts either as an electron donor via a photoinduced electron transfer pathway with Iod or as a proton/proton-coupled electron transfer promoter with MDEA or a thiol derivative. Two types of interpenetrated polymer n...

This investigation demonstrates the excellent photoinitiating properties of novel visible-light absorbing diphenylporphyrins (DPPs) for free-radical (FRP), cationic (CP) and thiol–ene polymerizations under visible LED irradiation (405 and 530 nm) at low intensities, under air or in laminate. Kinetics results on FRP and CP showed that DPPs are much more efficient photoinitiators than common Type II photosensitizers, i.e. camphorquinone or benzophenone. As confirmed by EPR and laser flash photolysis studies, DPPs play a dual role as an electron donor and in the H-abstraction reaction when combined with iodonium salt (Iod), N-methyldiethanol amine (MDEA) or thiol derivative, respectively.

We report for the first time the synthesis and use of a visible light-sensitive anthraquinone functional phthalocyanine (AQ-ZnPc) in combination with a suitable electron donor (methyldiethanol amin...

A facile strategy for the synthesis of nitrogen-doped, porous carbon materials was developed, with the first use of carbohydrate ionic liquids and salts as versatile precursors. Transformation of c...

Carbohydrate moieties were combined with various cross-linkable anions (thiocyanate [SCN], tetracyanoborate [TCB], tricyanomethanide [TCM], and dicyanamide [DCA]) and investigated as precursors for the synthesis of nitrogen-doped and nitrogen-/sulfur-co-doped carbons. The influence of the molecular structures of the precursors on their thermophysical properties and the properties of the derived carbon materials was elucidated and compared to petroleum-derived analogs. A carbohydrate-based ionic liquid featuring an [SCN] anion yielded more carbon residues upon carbonization than its 1-ethyl-3-methylimidazolium analog, and the resulting dual-doping of the derived carbon material translated to enhanced catalytic activity in the oxygen reduction reaction.

The photoactive layers of poly(terthiophene) with covalently attached fullerene photosensitizers were formed on indium–tin oxide (ITO) substrate in the process of electrochemical polymerization fro...

For many years, the research on conjugated polymers (CPs) has been mainly focused on their application in organic electronics. Recent works, however, show that due to the unique optical and photophysical properties of CPs, such as high absorption in UV–Vis or even near-infrared (NIR) region and efficient intra-/intermolecular energy transfer, which can be relatively easily optimized, CPs can be considered as an effective light-activated source of versatile and highly reactive singlet oxygen for medical or catalytic use. The aim of this short review is to present the novel possibilities that lie dormant in those exceptional polymers with the extended system of π-conjugated bonds.

Two highly efficient commercial organic photosensitizers—azure A (AA) and 5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin (APTPP)—were covalently attached to the glass surface to form a photoactive monolayer. The proposed straightforward strategy consists of three steps, i.e., the initial chemical grafting of 3-aminopropyltriethoxysilane (APTES) followed by two chemical postmodification steps. The chemical structure of the resulting mixed monolayer (MIX_TC_APTES@glass) was widely characterized by X-ray photoelectron (XPS) and Raman spectroscopies, while its photoactive properties were investigated in situ by UV–Vis spectroscopy with α-terpinene as a chemical trap. It was shown that both photosensitizers retain their activity toward light-activated generation of reactive oxygen species (ROS) after immobilization on the glassy surface and that the resulting nanolayer shows high stability. Thanks to the complementarity of the spectral properties of AA and APTPP, the effectiveness of the ROS photogeneration under broadband illumination can be optimized. The reported light-activated nanocoating demonstrated promising antimicrobial activity toward Escherichia coli (E. coli), by reducing the number of adhered bacteria compared to the unmodified glass surface.

There are many methods for incorporating organic corrosion inhibitors to oxide coatings formed on aluminum alloys. However, typically they require relatively concentrated solutions of inhibitors, possibly generating a problematic waste and/or are time-/energy-consuming (elevated temperature is usually needed). The authors propose a three-step method of oxide layer formation on 6061-T651 aluminum alloy (AAs) via alternating current (AC) plasma electrolytic oxidation (PEO), impregnation with an 8-hydroxyquinoline (8-HQ) solution, and final sealing by an additional direct current (DC) polarization in the original PEO electrolyte. The obtained coatings were characterized by scanning electron microscopy, roughness tests, contact angle measurements, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Additionally, corrosion resistance was assessed by potentiodynamic polarization in a NaCl solution. Two types of the coating were formed (A&mdash, thicker, more porous at 440 mA cm&minus, 2, B&mdash, thinner, more compact at 220 mA cm&minus, 2) on the AA substrate. The 8-HQ impregnation was successful as evidenced by XPS. It increased the contact angle only for the B coatings and improved the corrosion resistance of both coating systems. Additional DC treatment destroyed superficially adsorbed 8-HQ. However, it served to block the coating pores (contact angle &asymp, 80&deg, ) which improved the corrosion resistance of the coating systems. DC sealing alone did not bring about the same anti-corrosion properties as the combined 8-HQ impregnation and DC treatment which dispels the notion that the provision of the inhibitor was a needless step in the procedure. The proposed method of AA surface treatment suffered from unsatisfactory uniformity of the sealing for the thicker coatings, which needs to be amended in future efforts for optimization of the procedure.

Herein, we examine the synthesis of new polymers and characterize their physicochemical properties. A series of novel polymers based on polymethylsiloxane by catalytic hydrosilylation were successfully designed and synthetized. In order to enhance the polymers solubility, perylene diimide acted as the active functional group and poly(ethylene glycol) acted as the property modifying agent. Their structure was studied using 1H NMR and infrared spectroscopy. Grafting of PDI-allyl on polysiloxane led to mostly insoluble polymer. In contrast, the addition of poly(ethylene glycol)s co-grafts promoted good solubility in common solvents. UV-Vis and fluorescence spectroscopy, and atomic force microscopy were used to characterize the polymers. The generation of singlet oxygen by the prepared polymers, in which perylene diimide was the photosensitizer, demonstrated their applicability.

A performing photoinitiating system based on paprika spice was developed (i) to efficiently initiate, according to a green photoinduced process, the cationic polymerization of a biosourced and renewable monomer, e.g., gallic acid, and (ii) to synthesize environmentally friendly antibacterial coatings in a reduced time. A decrease of 100% of the adhered bacteria was demonstrated upon visible light illumination without any remaining live bacteria.

The work describes the in-situ Raman spectroelectrochemical studies on thionine layer covalently bound to the gold surface (Th/Au). The thionine layer was deposited on Au substrate via electrochemical reduction of corresponding diazonium salt. Due to the presence of system of conjugated bonds in the film’s structure, grafted thionine reveals electrochemical response analogical to unbound thionine. It is shown that bound Th can undergo irreversible oxidation leading to the formation of surface-bound radical cation and thus thionine dimers, as supported by cyclic voltammetry and Raman spectroelectrochemistry studies.

The selected group of four amine-derivatives of phenothiazine was covalently grafted to the glassy carbon surface in the four-step procedure consisting of the electrochemical reduction of the diazonium salt followed by the electrochemical and chemical post-modification steps. The proposed strategy involves the bonding of linker molecule to which the photosensitizer is attached. The synthesized organic layers were characterized by means of cyclic voltammetry, XPS and Raman Spectroscopy. It was shown that the phenothiazines immobilized via proposed strategy retain their photochemical properties and are able to generate 1 O 2 when activated by the laser radiation. The effectiveness of in situ singlet oxygen generation by those new solid photoactive materials was determined by means of UVVis spectroscopy. The reported, covalently modified solid surfaces may find their application as the singlet oxygen photogenerators in the fine chemicals’ synthesis or in the wastewater treatment.

Five selected amine-derivatives of phenothiazine were electropolymerized on an ITO/glass substrate and then used in the daylight-activated process to produce in situ singlet oxygen which degrades phenol in a solution. The phenothiazines were immobilized in a simple electrochemical procedure in an acidic solution which led to the formation of an ultrathin transparent polymeric film. All films obtained on the ITO substrate including azure A (AA), azure C (AC), methylene blue (MB), toluidine blue (TBO), and thionine (Th) had a comparable surface coverage at the level of picomoles/cm 2 . The activity of these materials was then compared and presented in terms of an efficiency of the phenol degradation process in an aqueous solution by photogenerated singlet oxygen. That efficiency was determined by the UV–vis spectroscopy employing a phenol/4-aminoantipyrine complex. All the phenothiazine ultrathin polymeric films were capable of generating the singlet oxygen in the aqueous solution under daylight activation, which was used in the consecutive process of phenol degradation. The highest efficiency at a level of 51.4% and 45.4% was found for the AC/ITO and MB/ITO layers, respectively.

Four amine-derivative phenothiazines were converted to the corresponding diazonium salt forms prior to their electrochemical grafting on the GC electrode with the aim to assess their ability to generate singlet oxygen. It was demonstrated by cyclic voltammetry and XPS spectroscopy that the molecular layers were effectively bound to the GC surface by applying the reductive potential in situ in the reaction diazo-mixture. The chosen procedure without the product separation step, appears to be especially useful due to the high solubility of the resulted phenothiazine diazonium salts. The effectiveness of singlet oxygen generation was measured for all of the grafted surfaces by UVVis spectra monitoring of the adjacent solution phase of 1,3-diphenylisobenzofuran (DPBF), which is well known trapping molecule used in detection of singlet oxygen. The data presented in the work prove that all of the molecular layers are effective singlet oxygen generators that might be used for various areas of applications where a highly oxidative reactant is required.

New conjugated polymers with perylene diimides (PDI) as pendant groups were synthesized and deposited on glass substrates by the spin coating. The resulting thin films were characterized by UV–vis, Raman spectroscopy, atomic force microscopy and profilometry. It was shown that PDI photosensitizers retain its photoactivity after covalent immobilization and the formed layers can be applied as efficient and environmentally stable source of singlet oxygen, 1O2, as tested with 1,3-diphenylisobenzofuran (DPBF) specific trap. Additionally, α-terpinene heterogeneous photooxidation was studied as the practical use of singlet oxygen generated by this novel PDI-based materials. The use of such heterogeneous source of singlet oxygen can be beneficial for the fine chemicals synthesis, due to simplified products isolation and purification step.

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.

Thionine (Th) was electrochemically grafted to the glassy carbon (GC) surface from its corresponding diazonium salt to investigate it as a singlet oxygen source under light excitation. As confirmed by cyclic voltammetry data the Th molecules may form a monolayer structure in the reduction process carried out directly from the diazotization reaction mixture without a time-consuming separation step. It was found that illuminated grafted Th at a level of monolayer coverage on GC surface is able to generate singlet oxygen at a constant rate. To determine efficiency of the photogeneration process a singlet oxygen selective trap, 1,3-diphenylisobenzofuran (DPBF), was employed, which was monitored using UVVis spectroscopy. The progress of the trap decay was determined in terms of its half-life. Keywords: Singlet oxygen, Phenothiazines, Photosensitizers, Photochemical generation, Electrografting

The paper presents results of investigations on a potential for utilisation of waste materials, containing silver powders, ceramics and polymer, for production of PTFE-matrix composites. The waste is a mix of Ag powders (10 – 15%), SiC and Al2O3 powders (20 – 50%) and polymeric powders (20 –50%). For composite production, high-temperature press moulding method was applied. Reinforcing materials and the matrix powder were mixed and subjected to the pressing process in a graphite mould at 350oC. Composite specimens containing 25% Ag, 50% Ag and 75% Ag were obtained. For the obtained composites, density, HB hardness and a friction coefficient were determined. The friction coefficient was evaluated in the “pin-on-block” test with the sliding distance of 2500 m and a load of 25 N with no lubrication. Wear of the composites was assessed based on a profilometry analysis. The obtained results suggest that the composites may be applied for manufacturing of components resistant to abrasive wear with a required, low friction coefficient.

The selected group of five amine-derivative phenothiazines was used to form their electropolymerized films in aqueous acidic solution with the aim to assess their ability to generate singlet oxygen. The films were characterized using cyclic voltammetry, UVVis spectroelectrochemistry, and Raman spectroscopy. The data of all the films were compared with properties of their monomer analogs. It was demonstrated that the electrochemically prepared films similarly to the known process of the corresponding monomers in solution phase are able to generate singlet oxygen in a photochemical surface process activated by laser radiation. These photogeneration process of the short-living species was monitored using the selected trap, which is detectable using UVVis spectroscopy. The effectiveness of the surface photogeneration reaction for each polymeric structure was determined in terms of half-life of the trap decay. The presented heterogeneous process of singlet oxygen photogeneration is believed to extend the area of applications of that highly oxidative reactant as compared to known homogeneous systems employing unbounded active species.

The work describes the in situ Raman spectroelectrochemical studies on polyaniline (PANi) thin films covalently bound to the modified gold surface. The PANi thin films were synthesized via surface-initiated electrochemical polymerization on gold substrates initially modified by the formation of self-assembled monolayer of 4-aminothiophenol, or comparatively by the electrografting of 4-nitrobenzenediazonium salt followed by the electrochemical reduction of aromatic nitro-groups to form aniline-containing monolayer. Due to the defined surface-chain bonding and the ordered polymer structure, the obtained thin PANi films exhibit a narrow peak separation of the polymer redox transitions and negatively shifted potential of its full oxidation, as revealed by the PANi Raman spectra recorded at controlled potentials and cyclic voltammetry measurements.

Fullerene, C60 photosensitizer was incorporated into poly(Azure A) in the process of electrochemical polymerization from the solution of corresponding dye and fullerene. The synthesized organic layer (PAA_C60/ITO) was characterized by means of cyclic voltammetry, UV–Vis, Raman and X-ray photoelectron spectroscopies. It was shown that PAA_C60/ITO exhibits strong absorption in both UV and Vis regions and that both immobilized photosensitizers, i.e. Azure A and C60, retain their photochemical activity towards 1O2 generation under illumination as tested with 2,3,4,5-tetraphenylcyclopentadienone (TPCPD) singlet oxygen quencher. The electrodeposited photoactive layer composed of two photosensitizers was investigated as a source of 1O2 in the process of α-terpinene oxidation.

A selenophene-containing fullerene dyad (C60Se) was electrochemically co-deposited with bis-selenophene (BisSe) to form a visible light absorbing poly(selenophene) layer with incorporated fullerene photosensitizers on platinum (Pt) or indium-tin oxide (ITO) substrates. The resulting photoactive films (P(C60Se_BisSe)) were characterized by cyclic voltammetry, UV–Vis, IR, Raman and X-ray photoelectron spectroscopies. The efficiency of P(C60Se_BisSe) towards singlet oxygen photogeneration was investigated by applying reactions with chemical traps, i.e. α-terpinene and 1,3–diphenylisobenzofuran (DPBF), monitored by UV–Vis spectroscopy. The composition of the electropolymerized layer was controlled by varying the monomers ratio in the feed solution and it had a strong influence on the spectroscopic and photosensitizing properties of the deposited film. It has been shown that the efficiency of the visible light-driven singlet oxygen generation can be increased by optimizing the ratio between C60 photosensitizers and organic units in the layer.