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Zinc acetate is used as a raw material to synthesize the desired ZnO in hot solvent by controlling the amount of citric acid (CA) added. Notably, the amount of CA added has a significant relationship with the control of the morphology of ZnO. Spherical ZnO wrapped in nanosheets is synthesized through the secondary crystallization of Zn2+. The optical properties of the ZnO sample are tested through the degradation of organic pollutants. Notably, the photocatalytic properties of ZnO vary with the different amounts of CA added. Exposure of the active crystal face increases the photocatalytic activity of ZnO. In addition, the number of defects on the surface of the ZnO sample increases because of its large specific surface area, thus changing the bandgap of ZnO. Therefore, the resulting sample can respond under visible light.

In this study, ZnO flowers were synthesized by a one-step hydrothermal method. On this basis, the ZnS nanoparticles were anchored uniformly on the surface of ZnO by a solution recrystallization strategy to form a ZnO@ZnS core-shell structure. A further increase in thiourea leads to the formation of a ZnS hollow structure, which is due to the Kirkendall effect. Throughout the process, the flower-like structure has not changed. The effects of the ZnS with different loadings on the morphology, crystallization properties, specific surface area, photoelectric response, and photocatalytic activity of the ZnO were investigated. The optimum ZnO@ZnS composite exhibited excellent photocatalytic activity of 757.07 μmol g−1 of H2 under simulated solar light irradiation. The results show that depositing an appropriate amount of ZnS nanoparticles on ZnO nanorods can effectively improve charge transfer. The charge transfer and the high specific surface area of the catalyst enhance the activity of photocatalytic H2 production.

As far as we know, the CO2 photoconversion reaction with H2O includes two important steps. One step is CO2 photoreduction (photogenerated electrons) while the other step is the oxidation of water (photogenerated holes). It is obvious that the oxidation of water is also the key step in the CO2 photoconversion reaction. However, little research has been done to improve the oxidation of water, thereby indirectly improving the photocatalytic CO2 reduction property of TiO2. Moreover, CO2 adsorption capacity is also considered as an important limiting factor for the CO2 photoconversion activity. Therefore, in this paper, CoPi (an amorphous cobalt-phosphate-based material) with high CO2 adsorption capacity was successfully immobilized on the surface of TiO2 nanosheets and served as a hole-cocatalyst to trap holes, thereby delaying the recombination of photogenerated electrons and holes and providing more CO2 gas to take part in the CO2 reduction reaction. Hence, the TiO2/CoPi exhibited much better CO2 photoconversion performance in water compared to pristine TiO2.

CdS and ZnS quantum dots were obtained via a modified gel crystal growth method using hydrogel (HR) as a kind of gel and a special substrate, which effectively suppressed the agglomeration of CdS and ZnS nanoparticles in the growth process via using chemical adsorption effect and utilizing the feature of gel crystal growth method (the sites of nuclei, growth and minimizing precipitation for the crystals were restricted spatially in the gel). The structural, growth mechanism and photocatalytic H2 evolution properties of these MS(M = Cd, Zn)/HR were investigated. The MS/HR composites exhibited high rates of H2 evolution compared to those of bulk MS, benefited to the synergistic effect of quantum dots and HR. The quantum dots extend the band gap and provide abundant catalytically-active sites and HR was used as a miniature hydrogen production reactor due to the large volumes of water in its swollen structure derived from its super H2O adsorption capacity, which efficiently avoided the agglomeration of MS quantum dots during the photocatalytic hydrogen evolution process. This work may provide an excellent approach for the preparation of quantum dots and miniature hydrogen production reactor shows a potential application in water splitting.

Black liquor, an industrial waste product of papermaking, is primarily used as a low-grade combustible energy source. Despite its high lignin content, the potential utility of black liquor as a feedstock in products manufacturing, remains to be exploited. Demonstrated here in is the use of black liquor as a primary feed-stock for synthesizing graphene quantum dots that exhibit both up-conversion and photoluminescence when excited using visible/near-infrared radiation, thereby enabling the photosensitization of ultraviolet-absorbing TiO2 nanosheets. In addition, these graphene quantum dots can trap photo-generated electrons to realize the effective separation of electron-hole pairs. Together, these two processes facilitate the solar-powered generation of H2 from H2 O, and CO from H2 O-CO2 , using broadband solar radiation.

Sodium ferric silicate nanosheets with ultrathin 2D structure were firstly synthesized by hydrothermal method using ferric nitrate and sodium silicate as precursors. The as-prepared nanosheets were characterized by SEM, TEM, AFM, XRD, XPS and N2-physisorption. Adsorption of ten dyes (including 5 cationic dyes and 5 anionic dyes) from aqueous solutions was investigated and discussed. The nanosheets were found to be amorphous and had a thickness of 0.85 nm. The ultrathin nanosheets displayed remarkable selective adsorption capacity toward cationic dyes due to the features of high specific surface area, negative charged surface and good mass transportation property. In particular, such ultrathin nanosheets showed a maximum adsorption capacity of 1.77 mg m−2 per unit surface area for methylene blue (MB), which is the highest value among the reported silicates adsorbents. The equilibrium adsorption data of MB suggested that the Langmuir model was much more suitable for the experimental data, and the pseudo-second-order kinetic equation could well describe the adsorption kinetics. Moreover, the sodium ferric silicate nanosheets could be regenerated by simple calcination and used repeatedly in dyes removal, demonstrating the potential application in wastewater purification and treatment.

Metal Bi is applied as the cocatalyst instead of noble metals, for the first time, in photocatalytic CO2 reduction and exhibits significant increase in CO yield compared to that of pristine photocatalyst, about 4.8 times. In situ photodeposition method is used to prepare metal Bi. Surprisingly, the average size of metal Bi obtained is ca. 5 nm and can be considered as quantum dots level, which is very difficult to be realized for noble metals via in situ photodeposition. Unfortunately, such small Bi is unstable in air, making it very difficult for the preservation. Another fortunate phenomenon is discovered, the unstable metal Bi can be stored via using the form of Bi/Bi2O3 quantum dots (Bi2O3 is main body of white Bi/Bi2O3 composites). When carried out the photocatalytic CO2 reduction, the white Bi/Bi2O3 can be easily transformed into grey Bi/Bi2O3 composites (the main body of grey Bi/Bi2O3 composites is metal Bi) to improve the photocatalytic CO2 reduction rate. This reason is that CB level of Bi2O3 quantum dots has shifted to a more negative position due to quantum confinement effect compared to the standard redox potential of Bi2O3/Bi (0.37 eV), leading to Bi2O3 easily to be reduced to metal Bi under the effect of photogenerated electrons derived from TiO2. This work demonstrated the mutual conversion between storage and utilization may offer an attractive approach for the application of unstable quantum dot materials or single atom materials.

Well dispersive CdS quantum dots (QDs) were successfully in-situ grown on cadmium hydroxyapatite (Cd5(PO4)3OH, Cd-Hap) assembled rods through a self-sacrificing hydrothermal method. No any nocuous organic ligands were used in such self-sacrificing route, allowing for a green approach to prepare CdS QDs with clean surfaces and enough active sites. The deposition of CdS QDs onto Cd-Hap surfaces led to a dramatically enhanced performance in H2 production under visible light irradiation as compared to bulk CdS nanoparticles. The optimal CdS QDs/Cd-Hap composite displayed a H2 evolution rate of 14.1 μmol h−1 without using any noble metal cocatalyst, which was about 4.2 times higher than that of pristine CdS. The apparent quantum efficiency for CdS QDs/Cd-Hap composite was up to 18%. It was also found that CdS QDs/Cd-Hap composite can continuously generate H2 from water in the presence of electron donors for more than 125 h. The enhanced photocatalytic performance of CdS QDs/Cd-Hap composites could be attributed to the high charge separation efficiency resulting from the efficient capture of photoinduced electrons by oxygen vacancies in Cd-Hap rods and the quantum confinement effect of CdS QDs with strong redox capacity as well as the increased active sites.

Carbon-aerogel is a kind of nano-porous carbon material with special three-dimensional network structure. Electrode materials with high specific surface area, high porosity, superior conductivity and low density were obtained by adding graphene to prepare graphene-doped carbon-aerogels.

Improving CO2 adsorption capacity, suppressing the recombination of carriers, and extending the light absorption range are key challenges for obtaining high efficiency photocatalytic conversion of CO2 with H2O as reducing agent. In this paper, we proposed using noble metal Ag and activated carbon obtained from biomass with high CO2 adsorption capacity to modify TiO2, thus assembling a TiO2/AC-Ag ternary composite photocatalyst via using ultrasonic and situ photodeposition methods. The TiO2/AC-Ag displayed six times increase in CO yield compared to that of pristine TiO2. The enhanced CO2 photoconversion performance can be attributed to the following three factors: (1) The activated carbon not only leads to enhanced CO2 adsorption capacity due to its properties and high surface area but also makes the electron transfer to its surface due to similar conductivity to metals derived from diverse electronic structures of activated carbon, thereby suppressing the recombination of photo-generated electron and hole pairs. (2) The oxidation reaction sites of H2O are located on the surface of TiO2 and the reduction reaction sites of CO2 are on the surface of activated carbon; the effective separation of two reaction sites remarkably inhibited the reverse reaction during CO generation. (3) The surface plasmon resonance (SPR) of Ag enables the materials to absorb light in a broader spectrum.

Hollow flower-like BiOI photocatalyst (h-BiOI) was obtained via a facile solvothermal method, which consists of ultrathin nanosheets with a thickness of about 2 nm. The structures and morphologies of as-prepared products were characterized by XRD and SEM and the absorption properties were determined by DRS. h-BiOI exhibit a more positive VB band than that of bulk BiOI (b-BiOI), which suggests a much stronger oxidation ability of the former. Therefore, h-BiOI displays completely degradation ability towards RhB under visible light irradiation while b-BiOI only decomposes RhB into segmental fragments under the same conditions. In addition, h-BiOI exhibits significantly higher antibacterial performances than b-BiOI under LED (470 nm) light irradiation. Besides the higher oxidation ability, the excellent photocatalytic activity of h-BiOI may be due to the ultrathin nanosheet, which takes less time for the photogenerated electrons and holes to reach the surface and therefore reduce their recombination.

Extending the light absorption of TiO2 to the visible region is realized using a colorless molecule (2-methoxyethanol). The as-prepared MES-TiO2 displays efficient photocatalytic activity under visible light irradiation. The hydrogen bond between MES and TiO2 is found to be responsible for the visible light absorption of TiO2, which is confirmed by FT-IR, DRS, PL spectra and density of states calculation.

Reasonable utilization of lignin in pre-hydrolysis liquor (PHL) is very important for the economic benefit of papermaking industry. In this paper, lignin in poplar pre-hydrolysis liquor (PHL) was effectively adsorbed by TiO2 nanosheets, realizing the purification of PHL. Subsequently, lignin was carbonized via thermal desorption for forming the carbon quantum dots immobilized on TiO2 nanosheets surface, which can improve both the separation efficiency of photogenerated carrier and CO2 adsorption capacity of TiO2, as a result the efficiency of photocatalytic CO2 reduction of C/TiO2 increased 300 % compared to the TiO2.

To enhance the photocatalytic activity of monoclinic BiVO4 for O2 evolution from water, Ce-doped BiVO4 was prepared using the one-pot facile solvothermal method and characterized via XRD, Raman, XPS, and electrochemical impedance spectroscopy (EIS). The XPS spectra confirm that Ce component is Ce3+ ions instead of Ce4+ ions. From the structural characterization and the calculations of formation energies it has been stated that the doping of Ce3+ ions takes place at Bi3+ sites without changing the host structure. The as-prepared Ce-doped BiVO4 samples display significantly enhanced photocatalytic O2 evolution activities from water compared to pristine BiVO4. Density of states calculations indicate that Ce3+ ions act as hole traps, thereby delaying the recombination of photogenerated electrons and holes. The results demonstrate that the substitution of the remaining monoclinic crystal structure may offer an attractive alternative approach for the doping of BiVO4 to enhance the evolution activity of photocat...

In order to solve environmental pollution problems, a kind of photocatalyst for high-efficiency utilization of sunlight is proposed. The simple solvothermal method is used to synthesize the ternary heterojunction g-C3N4/Ag/ZnO with 3D flower-like structure. The surface plasmon resonance effect of metal Ag can improve the response of photocatalyst to visible light. Electrons conduction at heterojunction interface can enhance the separation and transfer efficiency of photogenerated electrons and holes. The heterojunction g-C3N4/Ag/ZnO have excellent photocatalytic degradation efficiency and mineralization efficiency for different organic dyes, phenols reagents and antibiotics under visible light, such as 2,4-dichlorophenol, phenol and rhodamine B et al. Similarly, the photocatalytic activity of the ternary heterojunction g-C3N4/Ag/ZnO is optimal compared to the pure g-C3N4, g-C3N4/ZnO composite and g-C3N4/Ag composite. It can be known that the ternary heterojunction g-C3N4/Ag/ZnO has great photocatalytic stability through cyclic tests. The important role of hydroxyl radicals in photocatalytic reactions is confirmed by radical species quenching experiments.

TiO2 is one of the most studied in photocatalytic CO2 filed, while its efficiency was seriously limited by the weak adsorption ability for CO2 and low separation efficiency of charge carriers. Here a lewis base [WO4]2− was used to modify TiO2 via an in-situ ion exchange strategy. It was found that the prepared samples showed better performance in CO2 adsorption and carriers’ separation. As a result, the TiO2/[WO4]2− composites had exhibited good activities in photocatalytic CO2 reduction. The amount of generated CO was over 19 times that of the pure TiO2 and it was even much better than precious metal (Ag, Au) modified TiO2. Our experiment proves that this kind of modifying Lewis base method is an efficient strategy for enhancing the CO2 reduction activity of semiconductor photocatalysts.

As eries of amorphous silver silicates with differ- ent compositions were synthesized for the first time by one-step co-precipitation. Silicate ions were found to have important role on determining visible light absorption and photocatalytic activities of amorphous silver silicates ,a nd the sample with Ag/Si ratio of 3.20 exhibits optimal pho- tocatalytic activity.

Uniformly dispersed sulfur doped BiOCl was prepared via a one-pot solvothermal method, which displays higher photocatalytic activity towards oxygen evolution from water compared to pure BiOCl. This is associated with the impurity states above the valence band induced by S doping, which is beneficial for the separation of photo-generated electron–hole pairs.

Rubber composites were synthesized by natural rubber filled with cerium oxide with different particle diameters. The dispersion morphology of cerium oxide in rubber matrix and the mechanical properties of composites were studied, and the contrast experiment of reinforcing rubber with cerium oxide was performed. The results showed that the small particles of cerium oxide had better disparity than the large particles of cerium oxide in NR. The mechanical properties of rubber filled with small particles of cerium oxide were better than those of rubber filled with large particles of cerium oxide. The crystalline rubber was measured by X-ray diffraction, which indicated that the CeO2 accelerated crystallization capacity and confined the rubber chain movement. The tensile strength of rubber was increased by this confinement.

Lanthanum cyanurate was synthesized by reacting cyanuric acid and lanthanum nitrate at basic condition and was characterized by elemental analysis and Fourier transform infrared spectroscopy. Its application as thermal stabilizer for poly(vinyl chloride) (PVC) was investigated by Congo red test and discoloration test. In comparison with other heat stabilizers, including lanthanum stearate, calcium stearate, and zinc stearate, lanthanum cyanurate exhibits high stabilizing effect with excellent initial color of PVC. The stability time reaches the maximum (80 min) when the percentage of lanthanum cyanurate in PVC is 2.5%. The combination stabilizers (LaC3N3O3/Zn(St)2 obviously increase the complete discoloration time of PVC in comparison with the stabilizer of Zn(St)2. The stability time of PVC increases from 14 min (stabilized by zinc stearate) to 26 min (stabilized by LaC3N3O3/Zn(St)2). LaC3N3O3 also shows a slightly stronger effect on tensile strength of PVC than La(St)3. Therefore, the LaC3N3O3 can be used to replace La(St)3 and serve as a costabilizer to improve stabilization efficiency of calcium/zinc stabilizers for PVC. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Bi4V2O11 was prepared via a one-pot solvothermal method and characterized via XRD, Raman, XPS, Electrochemical impedance spectroscopy. The as-prepared Bi4V2O11 sample displays excellent photocatalytic activity towards oxygen evolution under light irradiation. The hierarchical structure is in favour of the spatial separation of photogenerated electrons and holes. Furthermore, the internal polar field also plays a role in improving the charge separation. Both of the two results are responsible for excellent activity of O2 evolution. The resulting hierarchical Bi4V2O11 sample should be very promising photocatalyst for the application of photocatalytic O2 evolution in the future.