High-Rate, Tunable Syngas Production with Artificial Photosynthetic Cells.

An artificial photosynthetic (APS) system consisting of a photoanodic semiconductor that harvests solar photons to split H2 O, a Ni-SNG cathodic catalyst for the dark reaction of CO2 reduction in a CO2 -saturated NaHCO3 solution, and a proton-conducting membrane enabled syngas production from CO2 and H2 O with solar-to-syngas energy-conversion efficiency of up to 13.6 %. The syngas CO/H2 ratio was tunable between 1:2 and 5:1. Integration of the APS system with photovoltaic cells led to an impressive overall quantum efficiency of 6.29 % for syngas production. The largest turnover frequency of 529.5 h-1 was recorded with a photoanodic N-TiO2 nanorod array for highly stable CO production. The CO-evolution rate reached a maximum of 154.9 mmol g-1 h-1 in the dark compartment of the APS cell. Scanning electrochemical-atomic force microscopy showed the localization of electrons on the single-nickel-atom sites of the Ni-SNG catalyst, thus confirming that the multielectron reduction of CO2 to CO was kinetically favored.

Visible-Light Driven Overall Conversion of CO2 and H2O to CH4 and O2 on 3D-SiC@2D-MoS2 Heterostructure.

A marigold-like SiC@MoS2 nanoflower with a unique Z-scheme structure efficiently achieves the overall conversion of gas phase CO2 with H2O (CO2 (g) + 2H2O (g) = CH4 + 2O2) without any sacrificial reagents under visible light (λ ≥ 420 nm) irradiation. The CH4 and O2 evolution are 323 and 621 µL·g-1·h-1, and stable throughout 5 cycle reactions of total 40 h. This work demonstrates a breakthrough in artificial photosynthesis with the Z-scheme 1D heterojunction constructed by combining 2D semiconductor and 3D semiconductor based on the transfer balance of photogenerated electron and hole.

Synergy of metal and nonmetal dopants for visible-light photocatalysis: a case-study of Sn and N co-doped TiO2.

This paper mainly focuses on the synergistic effect of Sn and N dopants to enhance the photocatalytic performance of anatase TiO2 under visible light or simulated solar light irradiation. The Sn and N co-doped TiO2 (SNT-x) photocatalysts were successfully prepared by the facile sol-gel method and the post-nitridation route in the temperature range of 400-550 °C. All the as-prepared samples were characterized in detail by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, X-ray photoelectron and electron spin resonance spectroscopy and photoelectrochemical measurements. The characterization results reveal that the co-incorporation of Sn and N atoms remarkably modifies the electronic structure of TiO2, which gives rise to a prominent separation of photogenerated charge carriers and more efficient interfacial charge-transfer reactions in a photocatalytic process. The enhanced photocatalytic activity is attributed to the intensified active oxygen species including hydroxyl radicals (˙OH) and superoxide anion radicals (O2˙(-)) for degradation of organic pollutants. And the result of photocatalytic hydrogen production further confirms the existence of the synergistic effect in the SNT-x samples, because they exhibit higher photocatalytic activity than the sum of N/TiO2 and Sn/TiO2. This work provides a paradigm to consolidate the understanding of the synergistic effect of metal and non-metal co-doped TiO2 in domains of photocatalysis and photoelectrochemistry.

[In situ IR study of surface hydroxyl and photocatalytic oxidation of toluene of rutile TiO2].

Abstract In the present work, the surface hydroxyls on rutile TiO2 that evacuated at different temperature were characterized by in suit FTIR The action of OH groups in photocatalytic reaction was tested by adsorption and photooxidation of toluene in an in situ IR cell. The results show that there are seven OH groups(with bands at 3 724, 3 700, 3 652, 3 648, 3 610, 3 413 and 3 362 cm-1) on rutile TiO2 with different thermal stability. Among the seven hydroxyl groups, the OH groups with bands at 3 724, 3 700 and 3 652 cm-1 are thermal stable and are ascribed to isolate hydroxyl groups, while the OH groups with bands at 3 648, 3 610, 3 413 and 3 362 cm-1 are thermal unstable that almost disappear after evacuation at 250 degreesC. During the adsorption of toluene, only the surface hydroxyls with bands 3 648, 3 610 and 3 652 cm-1 act as adsorption sites for adsorption of toluene.

Facile Preparation of the ZnSe/Ag2Se Binary Heterojunction for Photocatalytic Antibacterial Efficiency.

In a novel approach that capitalized on the differential solubility product (Ksp) of ZnSe and Ag2Se, a unique ZnSe/Ag2Se binary heterostructure was efficiently synthesized in situ. ZnSe/Ag2Se exhibited excellent antimicrobial efficiency under visible light. Incorporating Ag2Se into ZnSe significantly enhanced the photoelectric performance of the catalyst, greatly accelerating the separation of the photogenerated electrons in the system. Active species removal experiments determined that ·O2- and H2O2 played crucial roles in photocatalytic antibacterial efficiency. Further investigation into the levels of cellular membrane peroxidation, bacterial morphology, and intracellular contents concentration revealed that during the photocatalytic antimicrobial process, reactive oxygen species initially oxidize phospholipids in the cell membrane, leading to damage to the external structure of the cell and leakage of the intracellular contents, ultimately resulting in bacteria inactivation. The photocatalytic antimicrobial process of ZnSe/Ag2Se fundamentally deviates from conventional methods, offering new insights into efficient disinfection and photocatalytic antimicrobial mechanisms.

Photoinduced reactions between Pb3O4 and organic dyes in aqueous solution under visible light.

Pb(3)O(4) could react with organic dyes in aqueous solution under visible light irradiation, in which Pb(3)O(4) was transformed into Pb(3)(CO(3))(2)(OH)(2) along with oxidation of the organic dyes. Cu(2+) has considerable effect on the reaction. In the presence of Cu(2+), MO (20 ppm) and RhB (10(-5) mol L(-1)) were completely degraded under visible light within 6 and 20 min, respectively, while both Pb(3)O(4) and Cu(2+) keep almost stable during photodegradation. The mechanisms of the reactions with and without Cu(2+) ions were studied. The photochemical system of Pb(3)O(4) cooperating with Cu(2+) ions is probably used for the treatment of organic pollutants in water under visible light.

In situ IR study of surface hydroxyl species of dehydrated TiO2: towards understanding pivotal surface processes of TiO2 photocatalytic oxidation of toluene.

The surface species on P25-TiO(2) were characterized by FTIR after evacuation at 50-550 °C. The functions of OH groups on P25-TiO(2) catalysts have been tested by the adsorption and photooxidation of toluene in an in situ IR cell. FTIR studies show that the hydroxyl species on P25-TiO(2) are clearly temperature-dependent and P25-TiO(2) has six isolated hydroxyls with bands at 3734, 3715, 3688, 3671, 3658 and 3640 cm(-1). The OH groups on P25 play different roles in the photo-oxidation process: surface hydroxyls with bands at 3688, 3671, 3658 and 3640 cm(-1) act as adsorption sites while surface hydroxyls with bands at 3734 and 3715 cm(-1) act as sources of the ˙OH radical.

Enhanced bacterial disinfection by CuI-BiOI/rGO hydrogel under visible light irradiation.

Compared with traditional layered graphene, graphene hydrogels have been used to construct highly efficient visible light-excited photocatalysts due to their particular three-dimensional network structure and efficient electron transport capacity. In this work, CuI-BiOI/rGO hydrogel with excellent photocatalytic antibacterial activity was prepared and its activity against Escherichia coli and Staphylococcus aureus was evaluated. The result indicates that CuI-BiOI/rGO hydrogel exhibits superior sterilization performance and higher stability than CuI-BiOI and BiOI/rGO, and could completely kill Escherichia coli and Staphylococcus aureus within 40 min. However, only a small amount of Escherichia coli and Staphylococcus aureus can be inactivated by CuI-BiOI and BiOI/rGO hydrogels. Graphene hydrogel plays a significant part in enhancing the disinfection activity of CuI-BiOI/rGO hydrogel. Furthermore, the synergistic effect between CuI of p-type semiconductors, as a hole transport layer, and graphene hydrogel greatly increases the separation and transfer efficiency of photogenerated electron holes excited by BiOI, and further improves the disinfection activity of CuI-BiOI/rGO hydrogel.

In situ construction of a heterojunction over the surface of a sandwich structure semiconductor for highly efficient photocatalytic H2 evolution under visible light irradiation.

Developing a heterostructure on the surface of a "sandwich" structure semiconductor is essential for full utilization of its heterojunction function and hence for designing efficient solar energy conversion systems. Here, we show that 2D-2D MoS2/MnSb2S4 heterostructure composites are designed for the first time and successfully synthesized by a simple in situ calcination pathway. Under visible light irradiation, the ca. 3.3 wt% MoS2/MnSb2S4 samples exhibited the highest activity for H2 evolution, which was 7.7 times higher than that of the pristine MnSb2S4 monolayer. The outstanding photocatalytic performance was attributed to the MoS2 nanosheets intimately growing on the surface [SbS]+ layers of monolayer MnSb2S4 nanosheets with the [SbS]+-[MnS2]2--[SbS]+ sandwich substructure to form the 2D-2D MoS2/MnSb2S4 heterojunction structure. More importantly, we prove that this specific heterojunction structure can lead to more weakening of the constraint of the valence electrons in the composited photocatalysts, which can promote the transfer of photogenerated electrons from MnSb2S4 to MoS2. The present study provides a new design strategy for the construction of a heterostructure to improve the photocatalytic H2 production activity highly efficiently.

Cd3(C3N3S3)2 coordination polymer/graphene nanoarchitectures for enhanced photocatalytic H2O2 production under visible light.

For a long time, there has been global concern over the environment and energy problems. Recently, the problems, which have brought about serious effect on the global living condition, have been in the "spotlight" and given impetus to the universal's efforts to head for the same direction: stem the worst warming and strive for the renewable energy source. Hydrogen peroxide (H2O2) is undoubtedly a good choice, which holds the promise as a clean, efficient, safe and transferrable energy carrier. Octahedral coordination polymer, Cd3(C3N3S3)2, was found to be a robust photocatalyst for H2O2 generation under visible light irradiation. To further improve the H2O2 generation efficiency, adhering the octahedron to reduced graphene (rGO) was applied as the strategy herein. The study shows that by adhering Cd3(C3N3S3)2 to rGO, the formation of H2O2 is 2.5-fold enhanced and its deformation is concurrently suppressed. This work not only demonstrates the effectiveness of adhering Cd3(C3N3S3)2 polymer to rGO for the improvement of the polymer's photocatalytic performance, but also proposes a general way for the fabrication of graphene/coordination compound hybrids for maximizing their synergy.

Large-scale preparation of heterometallic chalcogenide MnSb2S4 monolayer nanosheets with a high visible-light photocatalytic activity for H2 evolution.

Free standing MnSb2S4 2D monolayer nanosheets were developed by a simple calcination of the neutral hydrazine molecule bridged chalcogenide, and were found to display a highly efficient and stable activity for photocatalytic hydrogen evolution from water under visible light irradiation (420-730 nm).

I-TiO2/PVC film with highly photocatalytic antibacterial activity under visible light.

Iodine-modified TiO2(I-TiO2) film were coated on medical-grade PVC material by impregnation-deposition method and subsequently characterized by XRD, SEM, TEM, AFM, DRS and XPS. The photocatalytic anti-bacterial activity of I-TiO2/PVC was investigated both by in vitro anti-bacterial experiments and by clinical study. The results revealed that I-TiO2/PVC exhibit excellent photocatalytic antibacterial activity, which can destroy the propagation of the Escherichia coli and cause the deactivation and death of most E. coli bacteria within 30min visible light illumination. Clinical study on animals showed that I-TiO2 coated on PVC decrease the formation of biofilm on PVC surface in the mechanical ventilation. Furthermore, I-TiO2/PVC can effectively reduce inflammation of tracheal tissue of bam suckling pig and prevents the occurrence of VAP.

[Study of photocatalytic performance of TiO2 membrane for oleic acid by FTIR-ATR technique].

The TiO2 membranes were prepared on glass, ceramic tile and aluminum pieces by Sol-Gel and PVD methods. A fast and exact evaluation on the photocatalytic self-cleaning performance of the membrane materials was achieved by FTIR-ATR technique using oleic acid which was laid on the surface of the membrane. The hydrophilic property of the samples was also determined by the contact angle with water. The results showed that both the TiO2 membrane prepared on glass by the Sol-Gel and PVD methods displayed good photo-induced hydrophilic property and degradation activity of oleic acid, and no difference in hydrophilic property, but the former was a little superior to the latter in photocatalytic activity. The photocatalytic conversion of oleic acid on the TiO2/glass, TiO2/ceramic tile and TiO2 aluminum piece were 92%, 85% and 46%, respectively after illumination 3.5 h, showing a distinct effect of support material property on TiO2 photocatalytic performance. The results suggested that the photocatalytic activity of TiO2 membrane coated on insulator support was higher than that coated on conductor support.

Robust Photocatalytic H2O2 Production by Octahedral Cd3(C3N3S3)2 Coordination Polymer under Visible Light.

Herein, we reported a octahedral Cd3(C3N3S3)2 coordination polymer as a new noble metal-free photocatalyst for robust photocatalytic H2O2 production from methanol/water solution. The coordination polymer can give an unprecedented H2O2 yield of ca. 110.0 mmol • L(-1) • g(-1) at pH = 2.8 under visible light illumination. The characterization results clearly revealed that the photocatalytic H2O2 production proceeds by a pathway of two-electron reduction of O2 on the catalyst surface. This work showed the potential perspective of Mx(C3N3S3)y (M = transitional metals) coordination polymers as a series of new materials for solar energy storage and conversion.

Monolayered Bi2WO6 nanosheets mimicking heterojunction interface with open surfaces for photocatalysis.

Two-dimensional-layered heterojunctions have attracted extensive interest recently due to their exciting behaviours in electronic/optoelectronic devices as well as solar energy conversion systems. However, layered heterojunction materials, especially those made by stacking different monolayers together by strong chemical bonds rather than by weak van der Waal interactions, are still challenging to fabricate. Here the monolayer Bi2WO6 with a sandwich substructure of [BiO](+)-[WO4](2-)-[BiO](+) is reported. This material may be characterized as a layered heterojunction with different monolayer oxides held together by chemical bonds. Coordinatively unsaturated Bi atoms are present as active sites on the surface. On irradiation, holes are generated directly on the active surface layer and electrons in the middle layer, which leads to the outstanding performances of the monolayer material in solar energy conversion. Our work provides a general bottom-up route for designing and preparing novel monolayer materials with ultrafast charge separation and active surface.

Photocatalytic and antibacterial properties of medical-grade PVC material coated with TiO2 film.

The TiO(2) film was coated on poly vinyl chloride (PVC) surface by dip-coating process from TiO(2)-PVC-THF suspension. The morphology and crystal structure of the as-synthesized samples were characterized by SEM and XRD. The photocatalytic properties were measured by the photodegradation reaction of RhB and the anti-adhesion and anti-bacteria for Escherichia coli. The results show that the resultant TiO(2) film is well-conglutinated on PVC surface and has the same crystal structure as the original TiO(2) powder. The TiO(2)/PVC shows excellent photocatalytic activity for the degradation of aqueous RhB and the activity increases with increasing reaction time and tends toward stable after accumulative illumination for 11.5 h. The TiO(2) film shows good bacterial anti-adhesion activity following photo-activation and sterilization property under UV irradiation. The E. coli can be killed completely after UV irradiation for 1.5 h.

[Photocatalytic functional ceramic and its speciality of photodecomposition].

Photocatalytic ceramic was prepared by coating photocatalytic membrane on ceramic matrix. The photocatalytic behavior of the TiO2 coated ceramic for degradation of oleic acid, ethylene, SO2, NOx and sterilization was studied by using XRD, chromatogram, in-situ IR and spectrophotometer. The results showed that the photocatalytic ceramic prepared by special conditions have the function of environmental conservation such as the photodegradating organic contaminants, removing inorganic baleful gas and killing bacteria. Degradation ratio of ethylene, oleic acid, SO2 and NOx reached 95%-100% respectively for the photocatalytic functional ceramic.