•Photoelectrocatalytic inactivation of E. coli by Cu2O film was firstly reported.•7 log of E. coli could be completely inactivated in 2 h by Cu2O with a 0.1 V bias.•Charge transfer between Cu2O and E. coli was monitored by electrochemical technique.•Inactivation of E. coli by electric charges of electrodes was in-depth investigated.•Stability of N-type Cu2O as a photocatalyst was studied for the first time.Photoelectrocatalytic (PEC) inactivation of Escherichia coli K-12 by cuprous oxide (Cu2O) film irradiated by visible light is firstly reported. A complete inactivation of about 7 log of E. coli was obtained for Cu2O film within 6 h. The bacterial inactivation efficiency was significantly improved in a photoelectrochemical cell, in which 7 log of E. coli could be completely inactivated within 2 h by Cu2O film with a 0.1 V bias. Electric charge transfer between electrodes and E. coli, and electric charge inactivation towards E. coli were investigated using membrane-separated reactor combined with short circuit photocurrent technique. H2O2, hole, and toxicity of Cu2O film were found responsible for the inactivation of E. coli. Toxicity of copper ions (including Cu2+ and Cu+) leakage from Cu2O films was determined and the results showed that the amount of leakage copper ions was not toxic to E. coli. Finally, the Cu2O film was proved to be effective and reusable for PC and PEC inactivation of E. coli.

•It is the first time to obtain TiO2 with high adsorption ability for dyes by one-pot preparation.•The prepared TiO2 can degrade dyes selectively under visible light.•Specific surface charge structure for the TiO2 is the main reason.•The prepared TiO2 can be used in waste-water treatment of targeted organics in practice.Particular TiO2 nanoparticles with high selective photocatalytic oxidation of anionic dyes are prepared by a feasible hydrothermal method. Moreover, its photocatalytic selectivity can be easily switched to cationic dyes by a simple post-treatment in ammonia solution, which makes the prepared TiO2 have bi-directional selectivity in dye photodegradation. Based on the photocatalytic performances and the structure and surface characteristics of the catalyst, the bi-directional selectivity of the catalysts is found to be closely related to the adsorption selectivity. The adsorption selectivity originates from surface charge groups, which are introduced during the preparation and post-treatment progresses. This study provides a facile and economical approach towards selective degradation of dyes with high efficiency by the special TiO2 nanoparticles synthesized through a simple hydrothermal method, which may be used practically in the future.

Flower-like SnS2 nanoparticles were synthesized through a hydrothermal process . By combing with hemoglobin (Hb) and the ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM]BF4), a composite biomaterial was fabricated and further used to modify a carbon ionic liquid electrode (CILE) with Nafion as a film-forming material. FT-IR and UV-Vis spectroscopic results showed that Hb retained its native structure in the composite. With the synergistic effects of the SnS2 nanoflower and IL, a couple of well-defined redox peaks of Hb appeared in the cyclic voltammogram of Nafion/Hb–SnS2–IL/CILE, which indicated that direct electron transfer between Hb and the underlying electrode was realized. The electrochemical behavior of Hb on the modified electrode was investigated by cyclic voltammetry with the electrochemical parameters such as electron transfer coefficient (α), electron transfer number (n) and heterogeneous electron transfer rate constant (ks) calculated. The fabricated electrode showed good electrocatalytic ability for the reduction of trichloroacetic acid (TCA) with a wider linear range from 0.8 to 21.0 mM and a lower detection limit of 0.27 mM (S/N = 3), indicating its potential application for the construction of a novel third-generation electrochemical biosensor.

•Nano-sized Li4Ti5O12 has been prepared through solid state reaction by using axiolitic TiO2 as precursor.•The prepared nano-sized Li4Ti5O12 anode material shows excellent electrochemical performance.•The utilization of precursor with special morphology and size is one of the useful ways to prepare more active electrode materials.Spinel nano-sized Li4Ti5O12 anode material of secondary lithium-ion battery has been successfully prepared by solid state reaction using axiolitic TiO2 assembled by 10–20 nm nanoparticles and Li2CO3 as precursors. The synthesis condition, grain size effect and corresponding electrochemical performance of the special Li4Ti5O12 have been studied in comparison with those of the normal Li4Ti5O12 originated from commercial TiO2. We also propose the mechanism that using the nano-scaled TiO2 with special structure and unexcess Li2CO3 as precursors can synthesize pure phase nano-sized Li4Ti5O12 at 800 °C through solid state reaction. The prepared nano-sized Li4Ti5O12 anode material for Li-ion batteries shows excellent capacity performance with rate capacity of 174.2, 164.0, 157.4, 146.4 and 129.6 mA h g−1 at 0.5, 1, 2, 5 and 10 C, respectively, and capacity retention of 95.1% after 100 cycles at 1 C. In addition, the specific capacity fade for the cell with the different Li4Ti5O12 active materials resulted from the increase of internal resistance after 100 cycles is compared.

•Sand flower LDHs have best CO2 adsorption ability.•The formation mechanism of sand flower LDHs is explored and discovered.•Mechanical stirring has great effect on the sand flower LDH formation.•The stability of the formed sand flower LDHs is related to treatment conditions.Magnesium–aluminum layered double oxides (Mg–Al-LDO) derived from calcination of layered double hydroxides (LDH) is one of the most capable candidates for CO2 capture. LDHs with sand flower and dense layered morphology are prepared by co-precipitation method at pH = 10 under different condition with and without stirring. The sand flower LDH prepared with stirring has better CO2 adsorption performance. Additionally, the sand flower morphology under calcination can be preserved very well, while the morphology can only remain stable below 100 °C after hydrothermal treatment and reconstruction. The formation process of the sand flower LDH is investigated in detail and the related morphology evolution mechanism is proposed. This study can provide insight into the effect of mechanical interaction on chemical reaction and give a new way to control the morphology of layered materials.

In doped CdS has been prepared by simple hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, UV–vis spectrometer, and X-ray photoelectron spectroscopy techniques. The photocatalytic activity of the prepared samples was tested by Rhodamine B degradation under simulated solar light with the comparison of pure CdS sample. The results show that all the prepared samples have fine crystallinity, and In3+/Cd2+ molar ratio greatly affects the morphology and photocatalytic activity of the samples. In doped CdS reveals enhanced photocatalytic activity compared with pure CdS. As for the photocatalytic mechanism of Rh-B over the prepared sample, hole and electron are responsible for the photocatalytic degradation and OH does not have strong contribution. So, hole and electron may not get converted to OH for Rh-B degradation. The as-prepared nanostructure samples may have application potential for environmental purification due to their high photocatalytic activity.Graphical abstractPhotocatalytic activity enhancement of CdS through In doping by simple hydrothermal method. A.M. Abdulkarem, E.M. Elssfah, Nan-Nan Yan, G. Demissie and Ying Yu .Highlights► In doped CdS is prepared by hydrothermal method. ► In doped CdS has better photocatalytic activity than pure CdS under VL. ► It is first time to use In ion to dope CdS for the activity improvement.

To study the mechanism of metal- and nonmetal-ion-doped TiO2, TiO2 codoped with carbon and molybdenum prepared by a hydrothermal method following calcination post-treatment is chosen as the study object. The prepared samples are characterized by X-ray diffractmeter, Raman spectroscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller measurement. It is found that the doped carbon exists in the form of deposited carbonaceous species on the surface of TiO2, and molybdenum substitutes for titanium in the lattice and exists as the Mo6+ state. All the prepared samples have comparable large surface areas. The photocatalytic activities are tested by degradation of rhodamine-B and acetone under visible light irradiation. The results show that the codoped sample has the best performance in the degradation of both RhB and acetone. Briefly, the enhanced photocatalytic activity of codoped TiO2 is the synergistic effect of C and Mo. Mo substitutes in the Ti site in the lattice for the formation of the doping energy level, and C exists as carbonaceous species on the surface of the TiO2, which can absorb visible light. The synergetic effects of C and Mo not only enhance the adsorption of visible light but also promote the separation of photogenerated electrons and holes, which consequently contribute to the best photodegradation efficiency of organic pollutants under visible-light irradiation. UV–vis diffuse reflectance spectra and photoluminescence spectra of the prepared samples and fluorescence of terephthalic acid for the detection of hydroxide radical are employed to verify the proposed mechanism.Keywords: C and Mo; mechanism; metal and nonmetal codoping; TiO2;

Bismuth vanadate nanotube (BV-NT), synthesized by a template-free solvothermal method, was used as an effective visible-light-driven (VLD) photocatalyst for inactivation of Escherichia coli K-12. The mechanism of photocatalytic bacterial inactivation was investigated by employing multiple scavengers combined with a simple partition system. The VLD photocatalytic bacterial inactivation by BV-NT did not allow any bacterial regrowth. The photogenerated h+ and reactive oxidative species derived from h+, such as •OHads, H2O2 and •HO2/•O2–, were the major reactive species for bacterial inactivation. The inactivation by h+ and •OHads required close contact between the BV-NT and bacterial cells, and only a limited amount of H2O2 could diffuse into the solution to inactivate bacterial cells. The direct oxidation effect of h+ to bacterial cells was confirmed by adopting F– surface modification and anaerobic experiments. The bacterial cells could trap e– in order to minimize e–-h+ recombination, especially under anaerobic condition. Transmission electron microscopic study indicated the destruction process of bacterial cell began from the cell wall to other cellular components. The •OHads was postulated to be more important than •OHbulk and was not supposed to be released very easily in the BV-NT bacterial inactivation system.

In this paper, carbon coated Fe3O4 nanospindles (C@Fe3O4 NSs) were synthesized by partial reduction of monodispersed hematite nanospindles with carbon coatings and applied to investigate the direct electrochemistry of myoglobin (Mb). A novel modified electrode was prepared by applying carbon coated Fe3O4 nanospindles, Mb, ionic liquid (IL), 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM]EtOSO3) and chitosan (CTS) step by step onto the surface of a carbon ionic liquid electrode (CILE) with another ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4), as the binder. UV-Vis absorption and FT-IR spectra results indicated that Mb retained its native structure in the composite film. The electrochemical behavior of the CTS/IL/Mb/C@Fe3O4/CILE was investigated and a pair of well-defined redox peaks appeared, which indicated that the direct electron transfer of Mb was realized with the underlying electrode. The fabricated CTS/IL/Mb/C@Fe3O4/CILE showed good electrocatalytic activity in the reduction of trichloroacetic acid (TCA) with a linear range from 1.0 to 20.0 mM, which showed potential applications for fabricating novel electrochemical biosensors and bioelectronic devices.

Zn-doped CdS nanoarchitectures with different Zn content are synthesized by a simple hydrothermal method with water as the only solvent. The prepared samples are characterized by X-ray powder diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectra, Brunauer–Emmett–Teller measurement, and X-ray photoelectron spectroscopy, while the photocatalytic activities are tested by photocatalytic degradation of rhodamine-B under visible-light irradiation. The results show that CdS with small amount of Zn doping can lead to an enhanced photocatalytic activity. Zn-doped CdS sample derived at 160 °C for 12 h with the molar ratio of Zn/Cd = 1:10 exhibits the best photocatalytic activity, which is much higher than that of pure CdS. Moreover, there is almost no loss of photocatalytic activity after four cycles of repeated experiments. So, Zn2+ doping indeed improves the photocatalytic activity and stability of CdS. Theoretical calculation indicates that Zn doping into a CdS crystal lattice can result in the shift of the valence band of CdS to a positive direction. It may lead to its higher oxidative ability than pure CdS, which is important for organic pollutant degradation under visible-light irradiation. Furthermore, the low formation energy for Zn-doped CdS systems demonstrates that the stability of CdS with Zn2+ doping can be improved. Experimentally and theoretically, this study will be useful for the improvement of photocatalytic activity and stability of CdS through the method of metal ion doping.

p-Type and n-type Cu2O thin films were controllably prepared using a simple solvothermal method by adjusting pH value of the copper (II) acetate aqueous solution. Photoelectrochemical experiments show that the Cu2O thin films synthesized in acid and alkaline (or neutral) media present n-type and p-type semiconductor character, respectively. Moreover, the films prepared at pH 5 have the best photoelectrochemical properties. The mechanism for the formation of these p-type and n-type Cu2O films is discussed. The Cu2O p–n homojunction fabricated in this study shows typical p–n junction character. This facile preparation method may be a promising way to prepare p–n homojunctions for semiconductor devices.

Photocatalytic experiment results under visible light demonstrate that both TiO2 and Cu2O have low activity for brilliant red X-3B degradation and neither can produce H2 from water splitting. In comparison, TiO2/Cu2O composite can do the both efficiently. Further investigation shows that the formation of Ti3+ under visible light has great contribution. The mechanism of photocatalytic reaction is proposed based on energy band theory and experimental results. The photogenerated electrons from Cu2O were captured by Ti4+ ions in TiO2 and Ti4+ ions were further reduced to Ti3+ ions. Thus, the photogenerated electrons were stored in Ti3+ ions as the form of energy. These electrons trapped in Ti3+ can be released if a suitable electron acceptor is present. So, the electrons can be transferred to the interface between the composite and solution to participate in photocatalytic reaction. XPS spectra of TiO2/Cu2O composite before and after visible light irradiation were carried out and provided evidence for the presence of Ti3+. The image of high-resolution transmission electron microscopy demonstrates that TiO2 combines with Cu2O tightly. So, the photogenerated electrons can be transferred from Cu2O to TiO2.Highlights► TiO2/Cu2O composite with bifunctional photocatalysis ability is prepared. ► The TiO2/Cu2O composite can degrade organic pollutant under VL. ► The TiO2/Cu2O composite can split water for H2 production under VL too. ► Ti3+ ions generated under VL plays an important role for the bifunctional.

Cuprous oxide (Cu2O) films with different nanostructures are deposited on different substrates of fluorine-doped SnO2 (FTO) glass, Cu and Ti foil respectively by using chemical bath deposition (CBD) technique with the presence of cetyltrimethylammonium bromide (CTAB). The samples are characterized by X-ray diffractmeter, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. The results show that the prepared Cu2O films are composed of nanorod arrays when there is CTAB in reaction system. Without CTAB, Cu2O films with nanospheres are formed. The concentration of CTAB is crucial for the controllable synthesis of nanorod structured Cu2O films with different length to diameter ratio and nanorod array density is dependent on both substrates and CTAB. A possible mechanism for the formation of Cu2O nanorods is discussed. Additionally, the UV–vis absorption property for Cu2O nanorods is much better than that for nanospheres. The photovoltage produced under visible light for Cu2O nanorod films is higher than that for the nanospheres. Although Cu2O nanorods on Ti foil can absorb the most visible light, those on Cu foil demonstrate better and more stable photoelectrochemical property than those on any other substrates. This study may be extremely useful for Cu2O based device with nanostructures.Research highlights► A simple CBD method used for preparation of Cu2O nanorods on different substrates. ► Nanorod array density and size is dependent on both substrates and CTAB concentration. ► Cu2O nanorods on Ti foil can absorb the most visible light. ► Cu2O nanorods on Cu foil demonstrate best and most stable photoelectricchemical property.

A new series visible-light driven photocatalysts (CuIn)xCd2(1−x)S2 was successfully synthesized by a simple and facile, low-temperature hydrothermal method. The synthesized materials were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area measurement, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV–Vis DRS). The results show that the morphology of the photocatalysts changes with the increase of x from 0.01 to 0.3 and their band gap can be correspondingly tuned from 2.37 eV to 2.30 eV. The (CuIn)xCd2(1−x)S2 nanocomposite show highly photocatalytic activities for H2 evolution from aqueous solutions containing sacrificial reagents, SO32− and S2− under visible light. Substantially, (CuIn)0.05Cd1.9S2 with the band gap of 2.36 eV exhibits the highest photocatalytic activity even without a Pt cocatalyst (649.9 μmol/(g h)). Theoretical calculations about electronic property of the (CuIn)xCd2(1−x)S2 indicate that Cu 3d and In 5s5p states should be responsible for the photocatalytic activity. Moreover, the deposition of Pt on the doping sample results in a substantial improvement in H2 evolution than the Pt-loaded pure CdS and the amount of H2 produced (2456 μmol/(g h)) in the Pt-loaded doping system is much higher than that of the latter (40.2 μmol/(g h)). The (CuIn)0.05Cd1.9S2 nanocomposite can keep the activity for a long time due to its stability in the photocatalytic process. Therefore, the doping of CuInS2 not only facilitates the photocatalytic activity of CdS for H2 evolution, but also improves its stability in photocatalytic process.

A simple approach is discovered for the synthesis of Cu2O films with periodic dimension transfer from sphere, rod to cone by chemical bath deposition technique. This two-step process consists of first immersing substrates into a copper thiosulfate solution followed by a subsequent dip in NaOH. The size and morphology of Cu2O films can be controlled by tuning the concentration of NaOH solution and adjusting immersion cycles (deposition times). Three-dimensional sphere, one-dimensional rod and three-dimensional cone Cu2O films can be periodically formed with the increase of the immersion cycles when the concentration of NaOH solution is less than 1.2 M and the immersion cycles are more than 10. The growth mechanism for such periodic pattern transfer of Cu2O films has been investigated and proposed. The photovoltaic characteristics of Cu2O films demonstrate that rod-like and cone-like Cu2O films have better photoelectric property than sphere-like Cu2O film under visible-light irradiation. This facile method may be used for the synthesis of other metal oxides films with special structures and good properties.

Experimental evidence shows that small Cu2O nanoparticles exhibit ferromagnetic or paramagnetic properties, allowing for the promising possibility to recycle the catalyst Cu2O easily in wastewater treatment. In this paper, theoretical calculation studying the magnetic property of copper/oxide clusters is reported. A series of CumOn ((m, n) = (4, 1); (4, 2); (4, 5); (16, 15); (28, 15); (44, 15); (28, 27)) clusters were investigated using generalized gradient approximation (GGA) and the Hubbard U (GGA+U) method within density functional theory (DFT). It is found that the electronic structures of bulk Cu2O calculated by the GGA and GGA+U are similar. The structures of CumOn ((m, n) = (4, 1); (4, 2); (4, 5)) are all planar. For the bulk-product CumOn ((m, n) = (16, 15); (28, 15); (44, 15); (28, 27)), O atoms prefer to be the outermost atoms. We classified two types of clusters on the basis of their O to Cu atomic ratios. One is O-rich clusters, i.e., Cu4O5, Cu16O15, and Cu28O27. The other is O-poor clusters, i.e., Cu4O, Cu4O2, Cu28O15, and Cu44O15. The calculation results show that the O-rich clusters have longer average Cu−Cu bonds and larger binding energy than those of the O-poor ones. More interestingly, the former are magnetic and give ferromagnetic ordering while the latter are nonmagnetic. The hydrogenation of O-terminated clusters can improve its stability but suppress its magnetism. The study may be extremely useful for the potential applications of Cu2O nanopaticles in the catalysis and semiconductor fields.

Cuprous oxide (Cu2O) films on Cu foils with a two-dimensional (2-D) nanosheet structure were first synthesized by polyol method with the assistance of acetamide and copper acetate as the copper source. The characterization results show that the prepared Cu2O nanosheets which are aligned on the Cu foils are single crystal with the thickness of ∼20 nm. The addition of acetamide is crucial for the controllable synthesis of 2-D nanosheet structured Cu2O films. Without the presence of acetamide, Cu2O films with granular morphology are formed. The growth mechanism is proposed according to the experimental results. Due to the aligned 2-D structure, the properties of the optical absorption and the charge carrier transportation for the novel Cu2O films are better than that for the Cu2O films with granular morphology. So, the films with 2-D aligned nanosheets morphology outperform the granular morphology in achieving higher photoelectrocurrent efficiency under simulated solar light. It makes the 2-D nanosheet structured Cu2O films more suitable for solar energy applications. In addition, a facile and efficient method is proposed here toward the preparation of films with novel structure on metal substrates (Cu, Al, Zn, etc.), for which a number of promising applications in various fields can be envisioned.

Flower-like SnS2 nanoparticles were synthesized through a hydrothermal process . By combing with hemoglobin (Hb) and the ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM]BF4), a composite biomaterial was fabricated and further used to modify a carbon ionic liquid electrode (CILE) with Nafion as a film-forming material. FT-IR and UV-Vis spectroscopic results showed that Hb retained its native structure in the composite. With the synergistic effects of the SnS2 nanoflower and IL, a couple of well-defined redox peaks of Hb appeared in the cyclic voltammogram of Nafion/Hb–SnS2–IL/CILE, which indicated that direct electron transfer between Hb and the underlying electrode was realized. The electrochemical behavior of Hb on the modified electrode was investigated by cyclic voltammetry with the electrochemical parameters such as electron transfer coefficient (α), electron transfer number (n) and heterogeneous electron transfer rate constant (ks) calculated. The fabricated electrode showed good electrocatalytic ability for the reduction of trichloroacetic acid (TCA) with a wider linear range from 0.8 to 21.0 mM and a lower detection limit of 0.27 mM (S/N = 3), indicating its potential application for the construction of a novel third-generation electrochemical biosensor.