Decomposition Of 2-propanol Research Articles

Cascade Reaction of Ethanol to Butadiene over Ag-Promoted, Silica- or Zeolite-Supported Ta, Y, Pr, or La Oxide Catalysts

Ethanol converts to 1,3-butadiene in the presence of suitable multifunctional catalysts. In this work, Lewis acid cations Ta, Y, Pr, and La were dispersed on amorphous silica or β zeolite, and after physically mixing with silica-supported Ag nanoparticles, were tested in the cascade reaction of ethanol to butadiene at 573 K. The Lewis acid catalysts were characterized by X-ray fluorescence, N2 physisorption, scanning transmission electron microscopy (STEM), X-ray diffraction, and diffuse reflectance (DR) UV–vis and X-ray photoelectron spectroscopies. High-resolution STEM images confirmed the small oxide cluster size on the silica support. Results from DR UV–vis spectroscopy showed that zeolite-supported Ta and Pr catalysts had a smaller metal oxide cluster size, relative to their SiO2 counterparts. X-ray photoelectron spectroscopy confirmed that the oxidation state of the cations supported on the zeolite remained the same as that of their SiO2-supported analogues. The selectivity of the C4 coupling products toward butadiene relative to butanol correlated with the acid strength of the Lewis acid cations, as evaluated by the 2-propanol decomposition reaction to propene and acetone, with Ta being the most selective. The rate of C–C coupling over the zeolite-supported cations was enhanced by an order of magnitude compared to those cations supported on amorphous SiO2.

Apatite-coated Ag/AgBr/TiO2 nanocomposites: Insights into the antimicrobial mechanism in the dark and under visible-light irradiation

For the first time, titania-based photocatalysts with different crystalline compositions (anatase/rutile) and morphology (irregular and faceted nanoparticles) were modified with Ag/AgBr and apatite (HA). The antimicrobial activity was tested for Escherichia coli (E. coli) bacteria and Candida albicans (C. albicans) fungi under visible-light illumination and in the dark for HA-covered and uncovered nanocomposites. It has been found that antimicrobial inactivation mechanism follows two different pathways, depending on the conditions (dark vs. irradiation), i.e., HA loading on the photocatalyst surface affects only the microorganism nourishment from the surrounding media (growth inhibition) in the dark, but significantly induces outer cell wall destruction (leading even to the mineralization) in the presence of light. Furthermore, 2-propanol oxidative decomposition was also investigated. The obtained results suggest that the improved photocatalytic activity of HA-covered samples originates from phosphate anions in HA, hindering the charge carriers’ recombination. In bacteria case, titania's properties are key factor for high bactericidal effects, such as anatase form (electrostatic attraction between microorganisms and photocatalyst surface) and fine crystallites, as opposed to yeast inactivation resembling 2-propanol oxidation, i.e., photocatalytic mechanism, based on reactive oxygen species. Concluding, HA/Ag/AgBr/TiO2 samples are promising “green” materials for decomposition of both microbiological and chemical pollutants.

Activation of Ethanol Transformation on Copper-Containing SBA-15 and MnSBA-15 Catalysts by the Presence of Oxygen in the Reaction Mixture.

The aim of this study was to get insight into the pathway of the acetaldehyde formation from ethanol (the rate-limiting step in the production of 1,3-butadiene) on Cu-SBA-15 and Cu-MnSBA-15 mesoporous molecular sieves. Physicochemical properties of the catalysts were investigated by XRD, N2 ads/des, Uv-vis, XPS, EPR, pyridine adsorption combined with FTIR, 2-propanol decomposition and 2,5-hexanedione cyclization and dehydration test reactions. Ethanol dehydrogenation to acetaldehyde (without and with oxygen) was studied in a flow system using the FTIR technique. In particular, the effect of Lewis acid and basic (Lewis and BrØnsted) sites, and the oxygen presence in the gas reaction mixture with ethanol on the activity and selectivity of copper catalysts, was assessed and discussed. Two different reaction pathways have been proposed depending on the reaction temperature and the presence or absence of oxygen in the flow of the reagents (via ethoxy intermediate way at 593 K, in ethanol flow, or ethoxide intermediate way at 473 K in the presence of ethanol and oxygen in the reaction mixture).

An Experimental Study of 2-Propanol Pyrolysis Chemistry.

In the present study, 2-propanol pyrolysis experiments were conducted in a rapid compression facility for a range of temperatures from 965 to 1193 K, pressures from 4.4 to 10.0 atm conditions, and times ranging from 2 to 47 ms after end-of-compression. Mixtures were composed of 2-propanol, nitrogen, and argon with the 2-propanol concentration held constant at 1.5% by mole fraction. The production of seven stable intermediate species (methane, acetylene, ethene, ethane, acetaldehyde, propene, and acetone) were measured using fast-gas sampling and gas chromatography. The high concentrations of propene observed experimentally indicated thermal decomposition of 2-propanol via dehydration was significant at all conditions studied. The observation of the simultaneous presence of methane and acetone indicated H atom abstraction from 2-propanol by H and CH3 radicals was also significant at all conditions. The relative concentrations of methane and acetone indicated an increase in the 2-propanol + CH3 channel at higher temperature. The experimental data showed negligible sensitivity to over a factor-of-two increase in pressure, indicating pressure-dependent reactions, like the thermal decomposition of 2-propanol via dehydration, were in the high-pressure limit. The experimental results were compared with model predictions made using a recently developed kinetic mechanism for C3-C4 alcohols, and the results showed generally good agreement. The most significant discrepancies were for 2-propanol consumption at the highest temperature condition (T = 1193 K), where 2-propanol consumption was predicted as much higher by the model (by more than an order of magnitude) compared with the experimental results, and at the lowest temperature (T = 965 K), ethane production was predicted as much lower (by more than an order of magnitude) compared with the experimental results.

MgO-containing porous carbon spheres derived from magnesium lignosulfonate as sustainable basic catalysts

The presence of alkalis in lignosulfonate allows an easy preparation of sustainable MgO-containing carbon catalysts with surface basicity by carbonization of magnesium lignosulfonate and/or further partial gasification of the produced char with CO2. Carbon spheres with different chemical and physical properties were obtained from lignosulfonate treated at temperatures ranging from 500 to 900 ºC. Carbonization at 900 °C generates hollow porous carbon spheres (pore volume of 0.20 cm3/g and apparent surface area of 465 m2/g) with magnesium content of 12%. A kinetic study of CO2 gasification of the carbon spheres obtained at 900 °C at temperatures in the range of 700 – 800 °C revealed that the gasification rate can be accurately described by the random pore model up to conversion values of 0.5. Based on this study, in order to develop additional porosity on the carbon spheres obtained at 900 °C, a partial gasification with CO2 at 750 °C for 30 min was carried out, reaching surface areas higher than 700 m2/g and 15.3% of Mg loading, with an overall preparation yield of 30%. All the obtained carbon materials were tested as catalyst for 2-propanol decomposition, showing a high selectivity to acetone, evidencing the basic character of these carbon catalysts. The highest activity and selectivity were shown by the CO2-activated carbon spheres (conversion and acetone selectivity higher than 90% at 420 °C), indicating that magnesium lignosulfonate is an attractive raw material for the preparation of sustainable carbon catalysts for biorefinery applications.

Ecomposition of 2-propanol over Alumina supported Thoria and Potassium ion modified catalysts

A series of alumina and K ion modified supported thoria catalysts were prepared using thorium nitrate hexahydrate at different loading levels (3–20 wt% of thoria) by the impregnating method. The decomposition of 2-propanol on the surface of these catalysts was investigated. Pure g-alumina catalyst shows low activity and higher selectivity towards dehydration reaction. In contrast, thoria catalyst shows low activity and higher selectivity towards dehydrogenation reaction. The activity and selectivity of alumina supported thoria catalyst towards dehydrogenation reaction was increased with increasing the amount of ThO2 on g-alumina. However, the activity and selectivity of these catalysts towards dehydration reaction were observed to be decreased with increasing the amount of ThO2. The surface of dehydrogenation reaction of 2-propanol was increased with increasing the addition of K ion on the surface of alumina supported thoria catalysts

Microwave-Assisted Base-Free Oxidation of Glucose with H2O2 on Gold- and Manganese-Containing SBA-15-Insight into Factors Affecting the Reaction Pathway.

The aim of this work was to gain insights into the role of manganese in MnSBA-15 support for gold in the base-free glucose oxidation with H2O2 using a microwave reactor. MnSBA-15 (manganese—acidity source) and SBA-15 (for comparison) were modified with Au (2.2 wt. %) and Cu (for comparison). The physicochemical properties of the catalysts were investigated by XRD, N2 ads/des, TEM, UV-vis, XPS, pyridine adsorption combined with FTIR, ATR-FTIR, and 2-propanol decomposition. The effects of the Mn presence in the support, Au NPs size that determines the number of active Au centers, and the Fermi energy (EF), together with the effects of the pore size, reaction temperature, and time on the activity and selectivity of the applied catalysts were assessed and discussed. It has been demonstrated that the presence of Mn generated Lewis acid centers which did not participate in glucose and H2O2 adsorption, and thus, were not directly involved in the reaction pathway. Both reagents were adsorbed on gold nanoparticles. H2O2 was decomposed to molecular oxygen which oxidized glucose to gluconic acid (50–90% of glucose conversion depending on the reaction time and ~100% selectivity). The presence of manganese in MnSBA-15 was responsible for increased Au NPs size and only slightly influenced the negative charge on gold particles. To achieve effective activity a compromise between the number of active gold species and the level of EF has to be reached (for 5.7 nm Au NPs).

Spherical Silica Modified with Magnesium and Ruthenium-Synthesis, Characterization and Catalytic Properties.

The design of different bimetallic catalysts is an important area of catalytic research in the context of their possible applications in the cascade processes, meeting the requirements of the so-called green chemistry. In this study, such catalysts were obtained by the incorporation of magnesium species into spherical silica, which was in the next step covered with porous silica and modified with ruthenium species. The structure and chemical composition of the materials obtained were determined by XRD measurements, low temperature N2 adsorption/desorption, SEM, ICP-OES and XPS methods. The catalytic activities of materials obtained were tested in 2-propanol decomposition and hydrogenation of levulinic acid. The results obtained confirmed the successful coverage of nanospheres with porous silica. A much higher concentration of ruthenium species was found on the surface of the catalysts than in their bulk. The opposite relationship was observed for magnesium species. The modification of nanospheres with silica had a positive effect on the catalytic activity of the materials obtained. For the most active sample, i.e., Ru/NS/3Mg/NS, 49% of levulinic acid conversion in its hydrogenation process was reported with γ-valerolactone as the only product.

Synthesis of Fe Catalysts Doped in SBA-15 by EISA Method: Characterization and Catalytic Studies in 2-Propanol Decomposition

Synthesis of Fe Catalysts Doped in SBA-15 by EISA Method: Characterization and Catalytic Studies in 2-Propanol Decomposition

Complete Decomposition of 2-Propanol Using TiO2 Immobilized on a Nonwoven Fabric Under UV Light Irradiation by Adding H2O2 and O3 Microbubbles

The degradation and mineralization of 2-propanol (IPA) in an aqueous solution were investigated using a TiO2 photocatalyst immobilized on a nonwoven fabric, both in the presence and absence of O3 microbubbles and H2O2. The influence of parameters like the H2O2/O3 molar ratio and the type of ultraviolet (UV) lamp used on the IPA degradation reaction was investigated. The main active species in IPA degradation and mineralization are thought to be hydroxyl radicals, generated as a consequence of the H2O2–O3 (peroxone) reaction, the photolysis of H2O2 and O3, and the TiO2-based photocatalytic reaction. The fastest IPA degradation rate was obtained under UV irradiation in the presence of H2O2, O3, and TiO2 immobilized on a nonwoven fabric. Because under these conditions sufficient UV light is irradiated on the catalyst surface, we found that the optimum ratio for the peroxone reaction between O3 and H2O2 did not change in our reaction system, even in the presence of the TiO2 immobilized nonwoven fabric. This means that the UV light contributes effectively to the photocatalytic reaction without interfering with the peroxone process, and that the photocatalyst does not only promote the decomposition of IPA but also the mineralization of the degradation products. We explored the influence of the base material used to manufacture the nonwoven fabric on the mineralization rate and found that the use of polyethylene terephthalate (instead of polyolefin fibers) to prepare the nonwoven fabric substantially accelerated the rates of the IPA, acetone, and total organic carbon decomposition reactions.

Preparation, Characterization and Catalytic Activity in 2-Propanol Conversion of Potassium and Antimony Mixed Oxides

Potassium and antimony mixed oxides were obtained by calcination of the commercial potassium-antimony tartrate trihydrate K(SbO)C4H4O6.3H2O at temperatures ranging from 300 to 800 °C. The structure varied with temperature as revealed by XRD characterization. The modifications occurring during the calcination process were also studied by FT-IR and DRS spectroscopies, along with by thermal analysis (TG/DTG). The solids were tested in 2-propanol decomposition at 200 °C, used as probe reaction for the investigation of acid-basic and redox properties. The catalytic activity was function of the calcination temperature and the best 2-propanol conversion was achieved with the tartrate precursor calcined at 500 °C that crystallizes forming KSbO3 as main phase along with K0.51Sb2.67O6.26 as secondary phase. Under N2 the activity reached the maximum after 10 min, 80% of 2-propanol conversion was the highest value, over the sample calcined at 500 °C, but rapidly decreased with time on stream and almost declined after 1 h. In the presence of air in the reaction mixture, 85% of 2-propanol conversion was achieved at 200 °C, after 20 min under stream, with the most active sample. By increasing the calcination temperature above 500 °C, the conversion decreased, especially for the sample calcined at 800 °C showing the worse conversion, although the stability over time increased, likely due to the achievement of stable crystalline phases and crystallite sizes. In all cases, the 2-propanone selectivity was close to 100%. This behaviour confirmed the occurrence of a dehydrogenation reaction involving the basic sites typical of KSbxOy oxides along with the redox couple Sb(V)/Sb(III).

Visible-light-driven photocatalysis via reductant-to-band charge transfer in Cr(III) nanocluster-loaded SrTiO3 system

Designing efficient visible-light-active photocatalysts is important for practical uses. Herein, strontium titanate (SrTiO3), a wide-bandgap semiconductor, loaded with chromium (III) nanoclusters has been demonstrated as a visible-light-active photocatalyst driven by the reductant-to-band charge transfer (RBCT) mechanism. The action spectrum revealed that absorption at around 430 nm contributed considerably to the photocatalytic 2-propanol decomposition. The reaction mechanism in the Cr(III)-loaded SrTiO3 system was studied by electron spin resonance (ESR) spectroscopy, electrochemical, and photoelectrochemical technique. We confirmed that the interfacial electron transfer (i.e., RBCT) from Cr(III) nanoclusters to the conduction band of SrTiO3 initiated the photocatalytic reaction under visible-light irradiation. In this system, moreover, the Cr(III) nanoclusters acted as a catalytic site for the efficient oxidation reaction. The RBCT mechanism opens new opportunities for other efficient wide-bandgap semiconductors to be active under visible-light irradiation and is expected to be applicable for a wider range of applications.

Preparation, Characterization and Catalytic Activity of CrSBA-15 for 2-Propanol Decomposition

The chromium mesoporous materials have been used in many catalytic reactions. Some studies have been devoted to determining the nature of chromium species and to characterizing the chemical structure. The different chromium species depend on synthetic methods and the support used. In this work we prepared mesoporous SBA-15 supported chromium materials referred to in this document as xCrSBA-15, was prepared by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen (N2) adsorption–desorption isotherms, hydrogen temperature-programmed reduction (H₂-TPR), scanning electron microscopic (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance ultraviolet-visible (UV–vis) and Fourier transform IR (FT-IR). Chromium in SBA-15 forms different types of chromates and Cr₂O₃, causing morphological and textural changes and generating different catalytic centers. The catalytic conversion of 2-propanol to xCrSBA-15 materials were carried out by in a quartz reactor with a loading of 30 mg of the material at 300°C. Before the catalytic test, the material was activated in two ways: with N₂ and reduced at a H₂/Ar flow (MxCrSBA-15). The catalytic conversion of 2-propanol to xCrSBA-15 did not increase with reduction (MxCrSBA-15) but decreased deactivation. All the materials had an acidic behavior, which is related to the chromate species in the materials. These results suggest that the more acidic materials favor the formation of coke during the deactivation process, and coke reduces the Cr³⁺ to Cr²⁺ species, thus decreasing the acidity of the materials.

The effect of support properties on n-octanol oxidation performed on gold – silver catalysts supported on MgO, ZnO and Nb2O5

Catalytic behaviour of supported nanometal catalysts for alcohols selective oxidation depends on the nature of the support and its surface. To identify the main feature that could explain these effects, supported mono- (Au) and bimetallic (AuAg) catalysts were prepared by using pure MgO, ZnO and Nb2O5, representative of three different types of oxides (basic, amphoteric and acidic, respectively), to get homogeneous metal-support interaction for each catalyst. The catalysts were characterized by XRD, N2 physisorption, TEM, UV–vis, XPS and 2-propanol decomposition as test reaction. It was found that the catalytic activity is influenced by the electron mobility between the gold nanoparticles and the support, which in turns depends on the intermediate electronegativity of the support. Selectivity in n-octanol oxidation was determined by redox properties of the gold species, the acid-base properties of the supports and the catalyst pretreatment. Silver addition modified the acid-base properties of the catalytic system, thus influencing the selectivity in n-octanol oxidation. Pretreatment of the catalyst (drying in air or thermal treatment in hydrogen flow) had a significant impact on its activity and selectivity.

Decomposition of 2-Propanol in the Liquid Phase Using a Photocatalyst Immobilized on Nonwoven Fabric and Ozone Microbubbles

2-Propanol (IPA) is a highly water-soluble volatile organic compound that is used in the cleaning and drying processes during semiconductor fabrication. IPA is also used as a disinfectant in the pharmacy field. Water scrubber processing is one of the methods used for IPA collection. However, water scrubbing requires wastewater treatment. In this study, we propose a decomposition system for IPA in the liquid phase based on a TiO2 photocatalyst immobilized on nonwoven fabric (TiO2 nonwoven fabric) and ozone microbubbles (MBs). The thick nonwoven fabric with immobilized TiO2 exhibits a higher IPA removal rate than that exhibited by the pleated fabric. IPA decomposes to produce acetone, which can be further decomposed and possibly undergo mineralization. The entire water tank can be supplied with ozone by introducing the MB-forming ozone, which considerably affects the decomposition of IPA. The efficient decomposition of IPA was achieved by combining ozone MBs, TiO2 nonwoven fabric, and ultraviolet irradiation, presumably because the photocatalyst promotes the mineralization of the decomposition product. Thus, the OH radicals from the O3 MBs competitively captured in the decomposition product strongly promote the decomposition of IPA, enhancing the IPA decomposition rate.

Effects of MoOx modification on photocatalytic activity of hydroxyapatite and Ti-doped hydroxyapatite

Titanium-doped hydroxyapatite (Ti-HAp, (Ca10-2x, Tix, □x) (PO4)6(OH)2, □: defect in Ca site) and hydroxyapatite (HAp, Ca10(PO4)6(OH)2) powders were modified with an ethanol solution of molybdenyl acetylacetonate (MoO2(C5H8O2)2) using chemisorption calcination cycle (CCC) technique, which provides metal oxide clusters. Their photocatalytic activity under UV illumination was evaluated by the decomposition of gaseous 2-propanol. The photocatalytic activity of the Mo-modified Ti-HAp samples increased concomitantly with increasing Mo concentration up to 0.72% against P. The highest photocatalytic activity of Mo-modified Ti-HAp was about 13 times higher than that of Ti-HAp. The signal appearance of Mo(V) in electron spin resonance spectra and the decrease of photoluminescence intensity suggest electron transfer from the Ti-hybridized band to the MoOx cluster, which suppresses recombination of the photoinduced electron and hole pairs. The photocatalytic activity of Mo-modified HAp samples was attributed to HOMO–LUMO excitation of MoOx cluster.

The influence of Zr presence in short channel SBA-15 on state and activity of metallic modifiers (Ag, Au, Cu, Fe)

Abstract Mesoporous silicas, SBA-15, synthesized with the addition of zirconium oxychloride (ZrOCl2) which ensures obtaining short channels, were used as supports for metallic modifiers including silver, copper, gold and iron. Different preparation routes of these materials, denoted as SBA-S (S stands for short channels), resulted in different morphologies and different contents of zirconium left after the preparation. Samples SBA-S1 and SBA-S2 were obtained after treatment with sulfuric acid (leaching of ca. 98.5% of zirconium ions), whereas SBA-S3 was not treated with H2SO4, which resulted in a higher zirconium content. Metallic catalysts were prepared by grafting of metal species on organosilane functionalized supports. Characterizations by X-ray diffraction, ultraviolet–visible spectroscopy and X-ray photoelectron spectroscopy allowed determination of the oxidation state of metallic modifiers and evidenced the interactions between the modifier (Ag, Au, Cu, Fe) and the zirconium that remained in the silica support. The reaction of 2-propanol decomposition and Fourier-transform infrared spectroscopy combined with adsorption of pyridine clearly showed the effect of zirconium on surface properties of metallic catalysts. Strong acidic Zr4+ species modified the surface acidic-basic properties of the catalysts. This phenomenon should be taken into account when the SBA-S materials are used as supports for potential catalytic applications. The reference material was the long channel SBA-15 (denoted as SBA-L) prepared and modified with metals by the same routes as the short channel materials.

Impact of Brønsted acid sites in MWW zeolites modified with cesium and amine species on Knoevenagel condensation

Abstract Layered zeolites of MWW family, MCM-22 and pillared MCM-36, were used as supports for base modifiers: cesium species (introduced via cation exchange or impregnation) and 3-aminopropyl trimethoxysilane (AP). The obtained materials were characterized by different methods (ICP-OES, N2 adsorption, XRD, XPS, TG/DTA, FTIR combined with pyridine adsorption, 2-propanol decomposition) for evaluation of chemical, structural and surface properties. All materials obtained were subjected to the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate and ethyl acetoacetate. The effect of the zeolite structure, the stability of the catalysts as well as acid-base properties of zeolites on the activity in Knoevenagel condensation were considered. Of particular interest was the role of Bronsted acid sites (BAS). The nature of basic sites and BAS played different roles depending on the methylene compound used in the Knoevenagel condensation. AP-modified zeolites were the most active in the condensation between benzaldehyde and ethyl cyanoacetate, in which, in the first step of the reaction AP abstracted hydrogen from methylene carbon in ethyl cyanoacetate. A different reaction pathway was postulated for the condensation with ethyl acetoacetate on the basis of the highest activity of unmodified zeolites and the relationship between benzaldehyde conversion and the number of BAS. For this reaction protonation of benzaldehyde was postulated as the initial step of the reaction.

Adsorption and Photocatalytic Decomposition of Gaseous 2-Propanol Using TiO2-Coated Porous Glass Fiber Cloth

Combinations of TiO2 photocatalysts and various adsorbents have been extensively investigated for eliminating volatile organic compounds (VOCs) at low concentrations. Herein, TiO2 and porous glass cloth composites were prepared by acid leaching and subsequent TiO2 dip-coating of the electrically applied glass (E-glass) cloth, and its adsorption and photocatalytic ability were investigated. Acid leaching increased the specific surface area of the E-glass cloth from 1 to 430 m2/g while maintaining sufficient mechanical strength for supporting TiO2. Further, the specific surface area remained large (290 m2/g) after TiO2 coating. In the photocatalytic decomposition of gaseous 2-propanol, the TiO2-coated porous glass cloth exhibited higher adsorption and photocatalytic decomposition ability than those exhibited by the TiO2-coated, non-porous glass cloth. The porous composite limited desorption of acetone, which is a decomposition intermediate of 2-propanol, until 2-propanol was completely decomposed to CO2. The CO2 generation rate was affected by the temperature condition (15 or 35 °C) and the water content (2 or 18 mg/L); the latter also influenced 2-propanol adsorption in photocatalytic decomposition. Both the conditions may change the diffusion and adsorption behavior of 2-propanol in the porous composite. As demonstrated by its high adsorption and photocatalytic ability, the composite (TiO2 and porous glass cloth) effectively eliminates VOCs, while decreasing the emission of harmful intermediates.

Photocatalytic and Antimicrobial Properties of Ag2O/TiO2 Heterojunction

Ag2O/TiO2 heterojunctions were prepared by a simple method, i.e., the grinding of argentous oxide with six different titania photocatalysts. The physicochemical properties of the obtained photocatalysts were characterized by diffuse-reflectance spectroscopy (DRS), X-ray powder diffraction (XRD) and scanning transmission electron microscopy (STEM) with an energy dispersive X-ray spectroscopy (EDS). The photocatalytic activity was investigated for the oxidative decomposition of acetic acid and methanol dehydrogenation under UV/vis irradiation and for the oxidative decomposition of phenol and 2-propanol under vis irradiation. Antimicrobial properties were tested for bacteria (Escherichia coli) and fungi (Candida albicans and Penicillium chrysogenum) under UV and vis irradiation and in the dark. Enhanced activity was observed under UV/vis (with synergism for fine anatase-containing samples) and vis irradiation for almost all samples. This suggests a hindered recombination of charge carriers by p-n heterojunction or Z-scheme mechanisms under UV irradiation and photo-excited electron transfer from Ag2O to TiO2 under vis irradiation. Improved antimicrobial properties were achieved, especially under vis irradiation, probably due to electrostatic attractions between the negative surface of microorganisms and the positively charged Ag2O.