The influence of coating with aminopropyl triethoxysilane and CuO/Cu2O nanoparticles on antimicrobial activity of cotton fabrics under dark conditions

A novel impregnation process for the fabrication of cotton nanocomposite with strong antimicrobial activity against antibiotics-resistant bacteria and yeast was developed. The impregnation process includes the sol–gel treatment of fabric with (3-aminopropyl)triethoxysilane in the first step, and synthesis of the CuO/Cu₂O nanoparticles (NPs) on the fabric surface in the second step. The in situ synthesis of the CuO/Cu₂O NPs was based on the adsorption of Cu²⁺-ions by the introduced amino groups of the sol–gel coating. The adsorbed Cu²⁺-ions are subsequently reduced in the alkaline solution of NaBH₄. X-ray diffraction measurements confirmed the formation of CuO/Cu₂O NPs. Scanning electron microscopy and atomic absorption spectrometry analyses indicate that the particle size, agglomeration, and amounts of synthesized NPs were highly affected by the initial concentration of CuSO₄ solution. The toxicity of nanocomposites to human keratinocytes (HaCaT) and antimicrobial activity against Gram-negative Escherichia coli ATCC 25922, E. coli ATCC BAA 2469, and Klebsiella pneumoniae ATCC BAA 2146, and Gram-positive bacteria Staphylococcus aureus ATCC 25923, S. aureus ATCC 43300 and yeast Candida albicans ATCC 24433 strongly depended on the copper content. In addition to excellent antimicrobial activity, controlled release of Cu²⁺-ions from the fabrics into physiological saline solution was obtained.     

Electro-conductive modification of polyethylene terephthalate fabric with nano carbon black and washing fastness improvement by dopamine self-polymerized layer

Modification of textiles with new applications target such as electroconductive fabrics has recently attracted researchers. In this article, carbon black nanoparticles (CB NPs) were applied to polyester fabric through two separate high temperature (HT) exhaustion processing with NaOH and cetyltrimethylammonium bromide (CTAB) as alkali hydrolysis catalyst and dispersing agents. To improve the stability of CB NPs on the fabric a self-polymerized compound, dopamine (DA) was used in a simple dipping method at room temperature for 24 h to form a thin layer of PDA on CB NPs-treated fabric. Field emission scanning electron microscopy (FESEM) was used to study the morphology of the fabrics confirming presence of CB NPs. EDX and mapping patterns showed the percentage and distribution of carbon, nitrogen, and oxygen elements on the fabric surface. The treated fabric indicated an electrical resistance of 14 kΩ turns a LED device on with a 10 V power supply. Self-polymerized DA on the fabric surface led to more nitrogen and oxygen caused higher CB NPs stability. Furthermore, the tensile strength results revealed a 25.8% lower tenacity on the treated fabric. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48035.     

Cationization of cellulose/polyamide on UV protection,bio‐activity,and electro‐conductivity of graphene oxide‐treated fabric

In this work, cationized cotton/nylon fabric was treated with reduced graphene oxide (rGO) to produce highly conductive fabric. The fabric was cationized with 3‐chloro‐2‐hydroxy propyl trimethyl ammonium chloride to attract more anionic GO. The fabric was then treated with GO followed by reduction with sodium dithionite. The results of energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy indicated entire coverage of the fabric surface with rGO. The color of fabrics changed to gray‐black and the electrical resistance decreased to 0.6 × 103 Ω sq^?1. The washing fastness was measured according to ISO 105‐CO5 for color change and also electrical resistance of the samples demonstrated well stability of rGO on the fabric surface. The antibacterial activities of the treated fabrics improved against Gram‐negative bacteria including Escherichia coli (84.8%) and Pseudomonas aeruginosa (96.4%) and also Gram‐positive bacteria consisting Staphylococcus aureus (100%) and Enterococcus faecalis (98.4%). Further, the treated fabrics indicated an excellent UV reflectance of 100%. Finally heating of the cationized rGO fabric at 220 °C displayed a lower electrical resistance of 0.5 × 103 Ω sq^?1. The thermogravimetric analysis showed that heating has a slight effect on the dimensional thermal stability of the treated fabric as shrunk 2.43%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45493.     

Hydrogenation of methyl acetate to ethanol by Cu/ZnO catalyst encapsulated in SBA‐15

The hydrogenation of methyl acetate (MA) is one of the important key processes for synthesis of ethanol from syngas. This work reports a highly efficient Cu‐ZnO/SBA‐15 catalyst prepared by facile solid‐state grinding method. Both copper and zinc species were encapsulated in SBA‐15 in high dispersion with the presence of organic template. The mixed homogeneity and interaction between copper and zinc species was enhanced as well with the help of organic template, resulting in the formation of Cu⁺ species in the reduced catalysts. Moreover, TOF_Cu(0) linearly increased with the Cu⁺/Cu⁰ ratio, indicating that a high proportion of Cu⁺/Cu⁰ induced by ZnO should be a key prerequisite to achieve favorable hydrogenation performance. It seems that the Cu⁺ species originated from Cu‐ZnO_x species are more active than that from Cu‐O‐Si species in the activation of MA. These results may provide an inspiration in rational design of Cu‐ZnO‐based catalysts for esters hydrogenation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2839–2849, 2017     

Crosslinking cotton with poly(itaconic acid) and in situ polymerization of itaconic acid: Fabric mechanical strength retention

Polycarboxylic acids have been used as nonformaldehyde durable press finishing agents for cotton fabrics. Previously, we found that itaconic acid (IA) polymerized in situ on cotton fabric and also in an aqueous solution in the presence of a K₂S₂O₈/NaH₂PO₂ initiation system. Both poly(itaconic acid) (PIA) and the polymer formed by in situ polymerization of IA are able to crosslink cotton cellulose, thus imparting wrinkle resistance to cotton. In this research, we compared the performance of the cotton fabric crosslinked by PIA and that crosslinked by in situ polymerization of IA. The fabric treated with PIA and that treated with IA had similar wrinkle recovery angles. The cotton fabric treated with IA, however, lost more tensile strength than that treated with PIA due to cellulose degradation. We determined the magnitude of the fabric tensile strength loss attributed to crosslinking by separating the tensile strength loss due to cellulose degradation from the total tensile strength loss, and found that the tensile strength loss caused by crosslinking for the fabric treated with PIA was significantly higher than that for the fabric treated with IA. This can probably be attributed to more concentrated crosslinkages formed on the near surface of the PIA‐treated cotton fabric. PIA had poorer penetration into the amorphous cellulose region in fiber interior due to its much larger molecular size, thus increasing its concentration on the fabric's near surface. The data also suggest that more concentrated crosslinkages on the fabric surface reduced fabric abrasion resistance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2023–2030, 2003     

A coloured polyester fabric with antimicrobial properties conferred by copper nanoparticles

In this study, we aimed to produce a coloured polyester fabric through the in situ sonosynthesis of copper nanoparticles using copper sulphate, hydrazine, sodium hydroxide and polyvinylpyrrolidone. The treated fabrics were characterised by X‐ray diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and elemental mapping. Moreover, mechanical properties, wettability and antibacterial/antifungal activities of the treated fabrics were evaluated. Central composite design based on the response surface methodology was used to study the effect of copper sulphate, hydrazine hydrate and sodium hydroxide on the weight gain and colour of the treated fabrics. In addition to their roles as reducing agents, hydrazine and sodium hydroxide were responsible for the simultaneous aminolysis and hydrolysis of polyester, increasing the adsorption of nanoparticles on the surface. According to the results, the reddish brown samples treated with copper nanoparticles showed excellent antibacterial and antifungal efficiencies, improved tensile strength and decreased wettability.     

Flame retardant finishing of the polyester/cotton blend fabric using a cross‐linkable hydroxy‐functional organophosphorus oligomer

Blend fabrics of cotton and polyester are widely used in apparel, but high flammability becomes a major obstacle for applications of those fabrics in fire protective clothing. The objective of this research was to investigate the flame retardant finishing of a 50/50 polyester/cotton blend fabric. It was discovered previously that N,N′‐dimethyloldihydroxyethyleneurea (DMDHEU) was able to bond a hydroxy‐functional organophosphorus oligomer (HFPO) onto 50/50 nylon/cotton blend fabrics. In this research, the HFPO/DMDHEU system was applied to a 50/50 polyester/cotton twill fabric. The polyester/cotton fabric treated with 36% HFPO and 10% DMDHEU achieved char length of 165 mm after 20 laundering cycles. The laundering durability of the treated fabric was attributed to the formation of polymeric cross‐linked networks. The HFPO/DMDHEU system significantly reduced peak heat release rate (PHRR) of cotton on the treated polyester/cotton blend fabric, but its effects on polyester were marginal. HFPO/DMDHEU reduced PHRR of both nylon and cotton on the treated nylon/cotton fabric. It was also discovered that the nitrogen of DMDHEU was synergistic to enhance the flame retardant performance of HFPO on the polyester/cotton fabric.     

Direct graphene growth on (111) Cu2O templates with atomic Cu surface layer

This work explores nucleation and epitaxy of graphene on crystalline Cu₂O templates formed via self-assembly and surface reduction of Cu₂O nanocrystallites on the cubic textured (100) orientation Cu (CTO-Cu) and polycrystalline Cu (poly-Cu) substrates, respectively. It has been found that the presence of sub-surface oxygen causes the reconstruction of Cu surface due to the formation of oriented Cu₂O nanocrystallites at a low H₂ gas flow. Self-assembly of the Cu₂O nanocrystallites into a textured surface template provides direct nucleation sites for graphene growth after the oxygen-sublattice on the template surface is reduced. The atomic Cu surface layer provides advantages of high graphene growth rate due to the catalytic role of Cu and in-plane alignment of graphene nuclei. It is particularly important that the Cu₂O crystallites have predominantly (111) orientation aligned to each other in the plane of the (100) CTO-Cu substrates, which allows epitaxy of graphene with much lower defect density as compared to that in the poly-Cu case. Since Cu₂O (111) templates may be developed on lattice matched (100) surfaces of other dielectric materials, this self-assembly approach provides a promising pathway for large-scale, transfer free graphene epitaxy on nonmetallic surfaces.     

Adsorption of Cu2+ ions with poly(N‐isopropylacrylamide‐co‐methacrylic acid) micro/nanoparticles

Chelation efficiency of stimuli‐responsive poly(N‐iospropylacrylamide‐co‐methyacrylic acid) (PNIPAAm‐MAA) nanoparticles with Cu²⁺ ions from CuSO₄·5H₂O solution and from wood treated with copper‐based preservatives was studied. It was shown that particle size played a very important role in the adsorption process. The nano‐scale particles showed much improved Cu ion adsorption efficiency, compared with the micro hydrogels. The amount of Cu ion adsorption increased with increase of MAA ratio in copolymers and adsorption efficiency decreased with increased particle size. Furthermore, the adsorption amount varied with adsorption temperature at temperatures both below and above the corresponding low critical solution temperature (LCST). The high adsorption efficiency of Cu ions by PNIPAAm‐MAA polymer particles provides an effective technique for recovering metal ions (e.g., Cu²⁺) from wood treated with metal‐based preservatives. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Shade darkening effect of polyorganosiloxane modified with amino and hydroxy groups on dyed polyester microfiber fabric

The novel polyorganosiloxane material S‐101 modified with amino and hydroxy groups is synthesized. Shade darkening effect of modified polyorganosiloxane on dyed polyester microfiber fabric is investigated by reflectance spectrum, color yield (K/S), and the color differences (ΔE). The colorimetric data of CIELAB is discussed. The results show that the novel material of silicone polymer modified with amino and hydroxy groups has excellent shade darkening effect on dyed polyester microfiber fabric. The rates of the color yield increase (I%) of all dyed fabric with four dyes (Disperse Yellow S‐4RL, Red GS, Blue 2BLN, and Black SF‐R) exceed 10%. The shapes of the reflectance spectra curves of the dyed fabrics before and after treated with S‐101 are not noticeable change. The dyed fabrics with the polymer have not significant effect on the wash fastness and wet rubbing fastness. The low reflectance thin film on dyed fabrics is formed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Multifunctional properties of polyester fabrics modified by corona discharge/air RF plasma and colloidal TiO2 nanoparticles

In this study the possibility of tailoring the textile nanocomposite materials based on the polyester fabric and TiO₂ nanoparticles that can simultaneously provide desirable level of antibacterial activity, UV protection, and self‐cleaning effects with long‐term durability was investigated. To enhance the binding efficiency of colloidal TiO₂ nanoparticles, the surface of polyester fabrics was activated by low‐pressure RF air plasma, and corona discharge at atmospheric pressure. Obtained functionalized textile materials provided maximum antibacterial efficiency against gram‐negative bacterium E. coli. High values of UV protection factor (UPF) indicate the maximum UV blocking efficiency (50+) of these fabrics. The results of self‐cleaning test with blueberry juice stains and photodegradation of methylene blue in aqueous solution confirmed excellent photocatalytic activity of TiO₂ nanoparticles deposited on the fiber surface. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Properties of Cu nanoparticles–poly(N‐methylpyrrole) composites

Spherical copper nanoparticles (Cu‐NPs) have been immobilized on the compact surface of potentiostatically generated poly(N‐methylpyrrole) (PNMPy) films by applying a reduction potential of −0.60 V to a deionized water solution of CuCl₂. Although the number density of Cu‐NPs obtained using this procedure is not high (4·10⁶ cm⁻²), the average diameter is relatively high (∼50 nm). The surface topology and roughness of films with Cu‐NPs–PNMPy are intermediate between those obtained for as prepared PNMPy and reduced PNMPy. Analysis of the electrochemical properties indicates that Cu‐NPs promote the electroactivity of the PNMPy, this effect being more evident for composited made with the thinnest PNMPy films. In opposition, the electrostability and electrical conductivity are not enhanced by deposited Cu‐NPs. Similar findings are obtained for bilayered PNMPy–Cu‐NPs–PNMPy films. POLYM. COMPOS., 37:594–601, 2016. © 2014 Society of Plastics Engineers     

Preparation of waste-based Cu–Cu2O/SiO2 photocatalyst from serpentine tailings and waste printed circuit boards and photoreduction of Cr(VI)

In China, a large amount of serpentine tailings and waste printed circuit boards (WPCBs) are produced every year. Serpentine tailings contain about 43% SiO₂ and WPCBs contain about 20% Cu. Reusing their resources can not only solve the problem of environmental pollution, but also produce certain economic benefits. In this study, waste-based SiO₂ support, waste-based Cu–Cu₂O and Cu–Cu₂O/SiO₂ photocatalyst were prepared using serpentine tailings and WPCBs as Si and Cu sources. The waste-based SiO₂ of 750 nm particle size was obtained by precipitation of 0.7 mol/L Na₂SiO₃ solution from the serpentine tailings and its specific surface area reached 57.72 m²/g after 600 °C calcination. Cu and the waste-based Cu–Cu₂O were loaded on the waste-based Cu₂O and SiO₂ support, respectively, and the phase structure of the catalysts has not changed by the characterization of SEM, XRD and XPS. The activity of the photocatalytic reduction of Cr (VI) with the waste-based catalysts showed in the following order: Cu₂O < Cu₂O/SiO₂<Cu–Cu₂O < Cu–Cu₂O/SiO₂, inferring by the investigation of photoelectric properties that Cu prevented the recombination of Cu₂O electron-hole pairs, the Cu–Cu₂O dispersed on SiO₂ support surface to obtain a higher specific surface area. The waste-based Cu–Cu₂O/SiO₂ photocatalyst showed no obvious deactivation after 5 cycles. The mechanism revealed that photogenerated electrons are the major reactive species for the photodegradation of Cr (VI). The study indicates that the waste-based Cu–Cu₂O/SiO₂ is potentially a developed, low-cost catalyst from sustainable resources. The production of Cu–Cu₂O/SiO₂ photocatalyst by using WPCBs and serpentine tailings represents the potential usage of waste into valuable material.     

Electrochemically synthesized polypyrrole and Cu‐plated nylon/spandex for electrotherapeutic pad electrode

Electroconductive fabrics were prepared to improve the properties of conductive electrode pad material used for electrotherapy when it is subjected to various movements of the human body. Highly stretchable and conductive fabrics were prepared by in situ electrochemical polymerization of polypyrrole (PPy) on nylon/spandex stretchable fabric in aqueous solutions with 0.05M pyrrole and 0.05M anthraquinone‐2‐sulfonic acid, sodium salt monohydrate (AQSA) at room temperature for 2 h. Electroless Cu plating was also applied after chemical polymerization of PPy to improve the conductivity of the fabric pad. Performance of prepared stretchable conductive fabric pad was evaluated in terms of conductivity changes as a function of extension and continuous current application time, and clinical test. As a result, the fabric conductivity was well maintained with extension up to 60% and prolonged treatment time over 30 min. The effect of transcutaneous electrical nerve stimulation (TENS) was observed with prepared TENS pad in this study and conventional TENS pad for medical use. The significant effect of TENS was observed with a pad made of conductive fabric by Cu plating and a conventional TENS pad (P < 0.05, respectively). Even though the efficiency of an experimental pad made of fabric composite with electrochemically polymerized PPy was not as good as conventional TENS pad for medical use in this experiment, it can possibly be used for other applications where relatively low‐strength electrical pulse is required. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4064–4071, 2004     

Modification of polyester fabric properties by surfactant‐aided surface polymerization

Poly(methyl methacrylate) (PMMA) was applied to polyester fabric using a surface analog of emulsion polymerization. The admicellar polymerization was carried out using 1.5 mM dodecylbenzenesulfonic acid (DBSA) at pH 4 with 0.15M NaCl, 1 : 8 DBSA:monomer, and 1 : 10 initiator:monomer molar ratio. The PMMA film, which was formed, was characterized by SEM and FTIR. Hydrolysis of the PMMA film on polyester fabric was carried out to introduce carboxylic acid groups to the polyester surface to increase its hydrophilicity. The results show that a PMMA thin film was successfully formed on the polyester fabric. The water contact angle of the PMMA‐coated polyester fabric after hydrolysis by 10M H₂SO₄ for 5 h was reduced from 117.3° to 0° and there was a significant increase in the moisture‐regain value of the treated fabric. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4059–4064, 2007     

Facile preparation of superhydrophobic polyester surfaces with fluoropolymer/SiO2 nanocomposites based on vinyl nanosilica hydrosols

A facile method to prepare superhydrophobic fluoropolymer/SiO₂ nanocomposites coating on polyester (PET) fabrics was presented. The vinyl nanosilica (V? SiO₂) hydrosols were prepared via one‐step water‐based sol‐gel reaction with vinyl trimethoxy silane as the precursors in the presence of the base catalyst and composite surfactant. Based on the V? SiO₂ hydrosol, a fluorinated acrylic polymer/silica (FAP/SiO₂) nanocomposite was prepared by emulsion polymerization. The FAP/SiO₂ nanocomposites were coated onto the polyester fabrics by one‐step process to achieve superhydrophobic surfaces. The results showed that silica nanoparticles were successfully incorporated into the FAP/SiO₂ nanocomposites, and a specific surface topography and a low surface free energy were simultaneously introduced onto PET fibers. The prepared PET fabric showed excellent superhydrophobicity with a water contact angle of 151.5° for a 5 μL water droplet and a water shedding angle of 12° for a 15 μL. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40340.     

Water and oil repellency of polysiloxanes with highly fluorinated alkyl side chains

A series of fluorinated polysiloxanes (FLSs) with the 3,3,4,4,5,5,6,6,6‐nonafluorohexyl group (C₄F₉C₂H₄? ), 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11‐heptadecafluoroundecyl group (C₈F₁₇C₃H₆? ), 3‐(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluorononanamido) propyl group [HDFNAG; C₈F₁₇(C?O)NHC₃H₆? ], and 3‐(N‐methyl‐2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluorononanamido) propyl group [C₈F₁₇(C?O)N(CH₃)C₃H₆? ] were synthesized. Their homopolymers (homo‐FLSs) and copolymers with dimethylsiloxane (co‐FLSs) were included. The polyester fabrics were treated with these FLSs, and their water and oil repellency was evaluated. These fabrics showed a moderate to good level of water repellency but a poor to zero level of oil repellency, except for those fabrics treated with homo‐FLSs with HDFNAG. The characterization of the surface chemical composition by X‐ray photoelectron spectroscopy showed that the concentration of fluorine at the surface was not particularly high for poly(ethylene terephthalate) films treated with homo‐FLSs with HDFNAG. Differential scanning calorimetry measurements of these FLSs revealed that only homo‐FLSs with HDFNAG had a high melting temperature of 75.7°C. These two measurements suggested that the reason the fabrics treated with homo‐FLSs with HDFNAG showed good oil repellency was not because the concentration of fluorine at the surface was much higher than for the others but because the reorientation of HDFNAG did not take place for its packing after contact with oil. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1085–1091, 2003     

Core‐shell ZrO2/PMMA composites via dispersion polymerization in supercritical fluid: Synthesis,characterization and mechanism

In this study, the polyester (PET) fabric was hydrolyzed with alkali to increase the surface activity and enhance the nano titanium dioxide (nano-TiO₂) adsorption to produce higher functionality. The PET fabric was first treated with sodium hydroxide along with cetyl trimethyl ammonium bromide as a cationic surfactant and then dipped into an ultrasound bath containing nano-TiO₂ followed by curing at high temperature. The weight loss, vertical wicking, and water droplet adsorption time were evaluated and are reported. The photocatalytic activity of TiO₂ nanoparticles deposited on the PET fabric was examined by the degradation of methylene blue as a model stain under daylight irradiation. The residual TiO₂ on the fabric surface after 1 and 10 successive washings was determined to indicate the washing durability of the finished fabric. Also, the UV protection was assessed by UV reflectance spectroscopy. The scanning electron microscopy pictures and energy-dispersive X-ray spectra of some fabrics are also reported. The surface hydrolysis of the PET fabric with sodium hydroxide created some voids and hydrophilic groups on the fabric surface; this led to the higher adsorption of nano-TiO₂ particles and enhanced the wettability, vertical wicking, and higher durability against repeated washings of the nano-TiO₂ treated fabric. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Photocatalytic decomposition of N2O on Cu+/Y-zeolite catalysts prepared by ion-exchange

Insitu characterization of Cu⁺/Y-zeolite catalysts and their photocatalytic reactivities for the decomposition of N₂O into N₂ and O₂ have been investigated by means ofin situ photoluminescence, XAFS, and ESR techniques along with an analysis of the reaction products. It was found that Cu(I) ions included within the nanopores of Y-zeolite exist as the [Cu(I)--Cu(I)] dimer species as well as the isolated Cu(I) monomer species, their ratio being much dependent on the SiO₂/Al₂O₃ ratio of Y-zeolite. UV irradiation of these Cu⁺/Y-zeolite catalysts in the presence of N₂O led to the photocatalytic decomposition of N₂O into N₂ and O₂ at temperatures as low as 275 K. The electronically excited state of Cu(I) ion (3d⁹4s¹ state) plays a vital role in the photocatalytic decomposition of N₂O into N₂ and O₂. The photocatalytic reactivity of these Cu⁺/zeolite catalysts was found to be strongly affected by the local structure of the Cu(I) ions which could easily be modified by changing the SiO₂/Al₂O₃ ratio of Y-zeolite. The isolated linear 2 coordinated Cu(I) monomer species formed on Y-zeolite having a moderate SiO₂/ A1₂O₃ ratio exhibited a high photocatalytic reactivity for the direct decomposition of N₂O into N₂ and O₂, clearly showing the importance of the coordinative unsaturation of the active sites.     

Oxidation of methanol on the surfaces of model Cu/ZnO catalysts containing Cu1+ and Cu0 species

Interaction of CH₃OH with Cu clusters deposited on ZnO films grown on a Zn foil as well as on a ZnO(0001)-Zn crystal, has been examined by X-ray photoelectron spectroscopy. On clean Cu clusters, reversible molecular adsorption or formation of CH₃O is observed. However if the Cu clusters are pretreated with oxygen, both CH₃O and HCOO^- species are produced. Model Cu/ZnO catalyst surfaces, containing both Cu¹⁺ and Cu⁰ species, show interesting oxidation properties. On a Cu⁰-rich catalyst surface, only CH₃O species is formed on interaction with CH₃OH. On a Cu¹⁺-rich surface, however, HCOO^- ion is the predominant species. This revised version was published online in July 2006 with corrections to the Cover Date.