Graphitic carbon nitride/ferroferric oxide/reduced graphene oxide nanocomposite as highly active visible light photocatalyst

High stability and efficient charge separation are two critical factors to construct high-performance photocatalysts.Here,an efficient strategy was provided to fabricate the nanocomposite of graphitic carbon nitride/ferroferric oxide/reduced graphene oxide(g-C_(3)N_(4)/Fe_(3)O_(4)/RGO).The degradation of rhodamine B(RhB)by g-C_(3)N_(4)/Fe_(3)O_(4)/RGO nanocomposite followed the pseudofirst-order kinetics.The g-C_(3)N_(4)/Fe_(3)O_(4)/RGO nanocomposite exhibited excellent stability and magnetically separable performance.It was ascertained that the quantum efficiency and separation efficiency of photoexcited charge carriers of g-C_(3)N_(4)/Fe_(3)O_(4)/RGO nanocomposite were obviously improved.Particularly,the g-C_(3)N_(4)/Fe_(3)O_(4)/RGO nanocomposite with 3 wt.%RGO presented 100%degradation efficiency under visible light irradiation for 75 min.The remarkable photocatalytic degradation activity is attributed to the synergistic interactions among g-C_(3)N_(4),Fe_(3)O_(4),and RGO,along with the efficient interfacial charge separation.

(N,F)-codoped TiO_2 Nanocrystals as Visible Light-activated Photocatalyst

（N, F）-codoped anatase TiO2 nanocrystals with active visible light response were prepared by using a simple sol-gel approach. X-ray photoelectron spectroscopy measurements suggested that the substitutional N and F species replaced the lattice oxygen atoms in TiO2 nanocrystals. Such nanocrystals showed strong absorption from 400 to 550 nm, which was mainly induced by nitrogen doping. The phase transformation from anatase to rutile was hindered by fluorine doping at high calcination temperatures, which was verified by XRD patterns. The N2 adsorption-desorption isotherms revealed the absence of mesopores in these nanocrystals. The （N, F）- codoped TiO2 nanocrystals showed satisfying photocatalytic activity on the photo-degradation of methylene blue under visible light.

S vacancy modulated Zn_(x)Cd_(1-x)S/CoP quantum dots for efficient H_(2) evolution from water splitting under visible light

Energy band structure and interfacial compatibility of heterojunctions are crucial for photocatalysts in promoting photogene rated charge separation and transfer.Here,a combined strategy of vacancy engineering and quantum effect via a facile phosphating process is reported,for the first time,to modulate the energy band structure and the interface of Zn_(x)Cd_(1-x)S/CoP quantum dots(ZCS_(v)/CoP QDs)heterojunction.The combined experimental and theoretical investigation revealed that phosphating process transformed CoO_(x) QDs to CoP QDs,and more importantly,generated considerable amount of sulfur vacancies in ZCS_(v).As a result,a TypeⅡZCS_(v)/CoP QDs heterojunction with compatible interfaces was constructed via in-situ generated P-Zn,P-Cd and S-Co bonds,which facilitated the separation and transfer of the photogenerated charge and thus resulted in a high ability towards hydrogen evolution under visible light(17.53 mmol g^(-1) h^(-1)).This work provides an effective and adaptable strategy to modulate band structure and interfacial compatibility of heterojunctions via vacancy engineering and quantum effect.

Visible light responsive photocatalysts developed by substitution with metal cations aiming at artificial photosynthesis

To solve resource,energy,and environmental issues,development of sustainable clean energy system is strongly required.In recent years,hydrogen has been paid much attention to as a clean energy.Solar hydrogen production by water splitting using a photocatalyst as artificial photosynthesis is a promising method to solve these issues.Efficient utilization of visible light comprised of solar light is essential for practical use.Three strategies,i.e.,doping,control of valence band,and formation of solid solution are often utilized as the useful methods to develop visible light responsive photocatalysts.This minireview introduces the recent work on visible-light-driven photocatalysts developed by substitution with metal cations of those strategies.

Recent progress on mixed-anion type visible-light induced photocatalysts

Environmentally friendly soft chemical processes, including solvothermal/hydrothermal process and mechanochemical process,for the synthesis of mixed anion type visible-lightinduced photocatalysts are introduced in this review paper. Titania and strontium titanate based anion doped photocatalysts can be effectively prepared at such low-temperature as below 200 ℃. Especially,the mechanochemical process is a useful method for the synthesis of various mixed ions doping functional materials at low temperatures. The mixed anion type photocatalytic compounds consisted of N/O, N/F/O, S/O, N/C/O, show excellent visible light absorption ability and photocatalytic activities, indicating the potential applications in environmental purifications. Full-spectra active long wavelength light induced photocatalyst, full-time active photocatalyst system and infrared radiation(IR) shielding multifunctional photocatalysts will be introduced also.

Visible light photodegradation of methylene blue by AgBr-TiO_2/SiO_2@Fe_3O_4 magnetic photocatalysts

Visible photoactive AgBr/TiO2 was immobilized on a SiO2@Fe3O4 magnetic support by solvother- rnal and sol-gel methods to form a AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalyst. Samples were characterized by X-ray diffraction, high-resolution transmission electron microscopy and magne- tometry. Hereto-structured AgBr/TiO2 was well seeded on the shell-core SiO2@Fe3O4 structure. The AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalyst exhibited high photocatalytic activity in the degrada- tion of methylene blue under visible light. The photocatalyst was superparamagnetic, which is beneficial for facile magnetic separation.

CeO_2-TiO_2 as a visible light active catalyst for the photoreduction of CO_2 to methanol

The performance of CeO2-TiO2 photocatalyst for the photocatalytic reduction of CO2 into methanol was studied under visible light irradiation. The as-prepared catalysts were characterized for their structural, textural and optical properties using X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, X-ray photoelectron spectroscopy（XPS）, nitrogen physisorption analysis, UV-vis spectroscopy and photoluminescence（PL） spectroscopy. The characterization results indicated that the presence of CeO2 stabilized the anatase phase of TiO2, decreased its crystallite size, increased the surface area, reduced the band gap energy and lowered the rate of electron-hole pair recombination. The CeO2-TiO2 photocatalyst showed an increased methanol yield of 18.6 μmol/g under visible light irradiation, compared to the bare TiO2（6.0 μmol/g）.

Modified TiO_(2) based photocatalysts for improved air and health quality

Photocatalysis with modified titania is a promising approach to improve both air and health quality.Modified titania with novel photocatalytic properties under indoor light irradiation leads to smart coatings,which are benchmark materials suitable for their indoor applications.It is generally accepted that the photocatalytic activity is affected by the light absorption,charge creation/recombination rate and surface reactivity.In this contribution we focus on modified TiO_(2) as catalyst in heterogeneous photocatalytic processes and address the efficiency of TiO_(2)-based building and construction materials on the removal of environmental pollutants indoors and outdoors.We also present data on the presence of eventually formed,toxicologically relevant and harmful by-products as the result of the photo-induced degradation of pollutants in an effort for better evaluation of induced risks for human health from the application of TiO_(2) modified materials.Finally,we present recent results on the disinfection performance of these material and the inactivation of severe pathogens contained in water and indoor air environments.

Preparation of sulfur hydrophobized plasmonic photocatalyst towards durable superhydrophobic coating material

The widely used photocatalytic self-cleaning coating materials are often made of polymers and polymer based composites,where the photocatalyst immobilization occurs with macromolecules.However,these organic polymers are often unstable under exposure to UV irradiation and easily degraded by reactive radicals produced in the photocatalytic reaction.In order to solve this problem,in this paper,we present the facile preparation of a multifunctional coating with dual superhydrophobic and photocatalytic properties,where the fixation and the hydrophobization of the plasmonic Ag-TiO2 photocatalyst particles with visible light activity was performed with non-water soluble sulfur,which is a cheap and easily available material.The resulted novel nanocomposite with rough and nano-tructured surface roughness(1.25–2.45 nm determined by small-angle X-ray scattering)has sufficient low surface energy(3.3 mJ/m2)for superhydrophobic(θ=151.1°v)properties.Moreover,in contrast of the organic and expensive fluoropolymer based composites,this non-wetting nature was durable,because the measured was higher than 150°during the long-term LED(λmax=405 nm)light irradiation.

Synthesis of band gap-tunable alkali metal modified graphitic carbon nitride with outstanding photocatalytic H_2O_2 production ability via molten salt method

Band gap-tunable alkali metal modified graphitic carbon nitride was prepared by a molten salt method. X-ray diffraction, N2 isothermal sorption, ultraviolet-visible spectroscopy, scanning electron microscope, X-ray photoelectron spectroscopy and photoluminescence were used to characterize the obtained cat-alysts. The photocatalytic H202 production ability of as-prepared catalyst was investigated. The results indicate that K＋ and Na＊ are doped into g-CBN4 lattice simultaneously by the molten salt method. Alkali metal modification not only promotes the specific surface area, visible light absorption and separation of electron-hole pairs, but tunes the conduction band and valence band edge positions of as-prepared catalysts by controlling the weight ratio of eutectic salts to melamine. The tunable band edge positions result in the photocatalytic H202 production from ＂single channel pathway＂ to ＂two channel pathway＂, leading to the promoted H202 production ability.

Simplified creation of polyester fabric supported Fe-based MOFs by an industrialized dyeing process: Conditions optimization, photocatalytics activity and polyvinyl alcohol removal

MIL-53(Fe) was successfully prepared and deposited on the surface carboxylated polyester(PET) fiber by an optimized conventional solvothermal or industrialized high temperature pressure exhaustion(HTPE) process to develop a PET fiber supported MIL-53(Fe) photocatalyst(MIL-Fe@PET) for the degradation of polyvinyl alcohol(PVA) in water under light emitting diode(LED) visible irradiation. On the basis of several characterizations, MIL-Fe@PET was tested for the photocalytic ability and degradation mechanism. It was found that temperature elevation significantly enhanced the formation and deposition of MIL-53(Fe) with better photocatalytic activity. However, higher temperature than 130℃ was not in favor of its photocatalytic activity. Increasing the number of surface carboxyl groups of the modified PET fiber could cause a liner improvement in MIL-53(Fe) loading content and photocatalytic ability. High visible irradiation intensity also dramatically increased photocatalytic ability and PVA degradation efficiency of MIL-Fe@PET. Na_(2)S_(2)O_(8) was used to replace H_(2)O_(2) as electron acceptor for further promoting PVA degradation in this system. MIL-Fe@PET prepared by HTPE process showed higher MIL-53(Fe) loading content and slightly lower PVA degradation efficiency than that prepared by solvothermal process at the same conditions. These findings provided a practical strategy for the large-scale production of the supported MIL-53(Fe) as a photocatalyst in the future.