•A novel AgI/Ag2CO3 heterojunction was prepared via coprecipitation process.•AgI/Ag2CO3 heterojunction increase e−/h+ pairs separation.•The production of •OH and O2•− radicals was promoted.•High ...photocatalytic activity and stability were obtained over AgI/Ag2CO3.
An insurmountable problem for silver-based semiconductor photocatalysts is their poor stability. Here, at room temperature, AgI with different concentrations (5%, 10%, 20% and 30%) were coupled into Ag2CO3, producing a series of novel AgI/Ag2CO3 composite photocatalysts. The effects of AgI addition on the Ag2CO3 catalyst for photocatalytic degradation of methyl orange (MO) under visible light irradiation have been investigated. Some physicochemical technologies like N2 physical adsorption/desorption, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS) were applied to characterize these products. Results show that the photocatalytic degradation activity of AgI/Ag2CO3 photocatalyst is much higher than that of pure AgI and Ag2CO3. With the optimal content of AgI (20wt%), the AgI/Ag2CO3 exhibits the highest photocatalytic degradation efficiency. Its first order reaction rate constant (0.54h−1) is 20 times of that of AgI (0.026h−1) and 3.6 times of that of Ag2CO3 (0.15h−1). The characterizations and theory calculation show that AgI and Ag2CO3 have suitably matched band gap structures. The formation of AgI/Ag2CO3 heterojunction with intimate interface could effectively increase the separation efficiency of the e−/h+ pairs and promote the production of •OH and O2•− radicals, which brings about the fast degradation rate of the dye and an increase in photocatalytic stability.
Novel Nd
3+
-doped
β
-Bi
2
O
3
/Bi
2
O
2
CO
3
composite nanoplates have been synthesized via a facile phase transformation route. The products generated in the phase transformation process of Nd
3+
...-doped Bi
2
O
2
CO
3
crystals were analyzed by a series of physicochemical techniques, e.g., TG-DTG, BET, XRD, SEM, TEM, FT-IR, and UV–vis DRS. The analysis results revealed that when the calcination temperature increased to 300℃, a phase transformation occurred (Bi
2
O
2
CO
3
→ Bi
2
O
3
). However, the doping of Nd
3+
could restrain the conversion of
β
-Bi
2
O
3
to
α
-Bi
2
O
3
and promote the stability of
β
-Bi
2
O
3
crystal phase during the cooling process. The obtained Nd
3+
/
β
-Bi
2
O
3
/Bi
2
O
2
CO
3
composite nanoplates possess superior visible light photocatalytic performance in the decomposition of phenols (phenol, 2,4-dichlorophenol, bisphenol A, 4-nitrophenol) and acid orange II. The intimate
β
-Bi
2
O
3
/Bi
2
O
2
CO
3
heterojunction largely boosted the separation of photo-generated electrons and holes. Moreover, the doped Nd
3+
could also participate in the capture of electrons. Thus, more photo-generated electrons and holes are available to participate in the decomposition of pollutants.
Graphical abstract
The Nd
3+
doped
β
-Bi
2
O
3
/Bi
2
O
2
CO
3
composite nanosheets synthesized
via
a facile phase transformation route display superior visible light photocatalytic performance for phenols (phenol, 2,4-dichlorophenol, bisphenol A, 4-nitrophenol) and dye mineralization.
Three-dimensional crumpled graphene (PRGO) was synthesized from graphene oxide (GO) solution by the spay drying method and employed as the support material for the Pd catalyst. The as-prepared ...catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunnel electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electro-catalytic activity and stability toward formic acid oxidation were investigated using cyclic voltammetry (CV) and chronoamperometry (CA), which indicated that the Pd/PRGO catalyst exhibits a larger electrochemically active surface area and mass activity as well as higher long term-stability in comparison to the commercial Pd/C and Pd/RGO catalysts. The enhanced catalytic performance is attributed to the high specific surface area of the 3D formation and utilization efficiency of Pd during the oxidation of formic acid.
Three-dimensional crumpled graphene (PRGO) was synthesized from graphene oxide (GO) solution by the spay drying method and employed as the support material for the Pd catalyst. Compared with the commercial Pd/C and Pd/RGO catalysts, the as-prepared Pd/PRGO catalyst exhibits excellent activity and stability towards formic acid electrooxidation.
A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical ...characterizations like N2 physical adsorption, X-ray powder diffraction（XRD）, scanning electron microscope（SEM）, transmission electron microscope（TEM）, UV–Vis diffuse reflectance（UV–Vis DRS）, Fourier transform infrared spectroscopy（FT-IR）,photoelectrochemical measurements, and photoluminescence（PL） spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi2O3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi2O3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi2O3 displayed much higher photocatalytic performance than that of bare Bi2O3, single La or Ce doped Bi2O3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons（e~-） and holes（h~＋）.
A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, ...X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectroscopy, hydrogen temperature-programmed reduction （Hz-TPR）, X-ray photoelectron spectroscopy （XPS） and thermogravimetry analysis （TGA）. The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity （GHSV） and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane （CPOM） were investigated. Catalytic activity test results show that the highest methane conversion （〉85%）, the best selectivities to carbon monoxide （〉87%） and to hydrogen （〉95%）, the excellent stability and perfect Hz/CO ratio （2.0） can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2 ratio of 2 ： 1 and gas hourly space velocity of 12000 mL.h-1 .g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area （~108 m2.g-1）, small crystallite size, easy reducibility and low coking rate.
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► Novel PbWO4 microspheres with hierarchical nanostructures were synthesized. ► The morphology and photocatalytic performance of PbWO4 crystals were controlled by pH value in ...preparation. ► PbWO4 microspheres exhibited remarkable photocatalytic activity and stability. ► Hierarchical structures and low recombination rate of the e−/h+ pairs enhanced photocatalytic performance.
Novel PbWO4 crystals with different morphologies, 14-faceted polyhedrons, hierarchical microspheres and nanoparticles, were fabricated by adjusting pH value under hydrothermal conditions. The as-prepared PbWO4 samples were characterized by nitrogen-physical adsorption, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra, photoluminescence emission spectroscopy, and Fourier transform infrared spectroscopy. The photocatalytic performance of the PbWO4 crystals with different nanostructures in degradation of the acid orange II dye under UV light (365nm) was investigated. The plausible growth mechanisms for PbWO4 crystals with different morphologies were proposed. Photocatalytic tests showed that the performance of PbWO4 crystals strongly depended on their morphologies. PbWO4 microspheres with hierarchical nanostructures prepared under pH 7.0 at 140°C exhibited the highest activity and stability in recycling reaction. The degradation kinetics of dye over PbWO4 crystals was found to conform to the pseudo-first order model. The enhanced photocatalytic performance was attributed to the unique hierarchical nanostructures with high surface area and improved surface properties. Moreover, the high crystallinity of PbWO4 microspheres exhibited an enhanced catalytic activity owing to lower recombination rate of photo-generated electron/hole pairs. These novel hierarchical PbWO4 microspheres hold promise in applications of environmental purification.
An ultrasonic method was developed to fabricate novel mesoporous TiO2 nanocrystals doped with a high concentration of N (N/TiO2). The nanocrystals were characterized by physicochemical methods ...including N2 physical adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic degradation of dimethyl phthalate, a hazardous chemical in water, by the prepared N/TiO2 nanocrystals under visible light irradiation (400–660 nm) was investigated. The results show that N-doping efficiency under ultrasonic irradiation is 3.2 times higher than under typical conditions, and the produced TiO2 nanocrystals have mesoporous structure. N/TiO2 fabricated under ultrasound exhibited much higher efficiency for the degradation of dimethyl phthalate than that prepared under typical conditions. The high photocatalytic degradation activity of N/TiO2 fabricated under ultrasound is mainly attributed to its high N content effectively increasing its ability to absorb visible light.
采用超声波辐射法制备了具有介孔结构的高浓度氮掺杂TiO2纳米晶(N/TiO2). 采用N2物理吸附/X射线粉末衍射/X射线光电子能谱/透射电镜/光致发光谱和紫外-可见漫反射光谱等手段对N/TiO2进行了表征. 以波长为400–660 nm的可见光为光源, 以水体污染物邻苯二甲酸二甲酯为降解对象, 考察了不同制备方法对N/TiO2光催化性能的影响. 结果表明, 超声波辐射使氮掺杂浓度提高了2.2倍, 该法制备的N/TiO2同时具有较好的介孔结构, 表现了更高的光催化降解邻苯二甲酸二甲酯的活性. 其活性提高的主要原因是N/TiO2含有更高浓度的氮和对可见光具有更强的吸收能力.
An ultrasonic method was developed to fabricate mesoporous TiO2 nanocrystals doped with high concentration of N. N doping causes strong visible light absorption and high photocatalytic activity towards degradation of dimethyl phthalate under visible light irradiation.
The fluorine doped Sn3O4 strengthened the redoxpotential. Moreover, the phenols and Cr(VI) acted as sacrificial agent of h+/OH and e−, respectively, which remarkably enables the efficient utilization ...of photoinduced electron-hole pairs.
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•The unique fluorine doped hierarchical Sn3O4 microspheres were first reported.•F doping enhanced light harvesting and boosted active radical generation.•Low recombination rate of free charge carrier was obtained.•F-Sn3O4 microspheres are promising for removing organic pollutants and Cr(VI).
Here, novel fluorine doped Sn3O4 microspheres with highly photocatalytic performance were reported. UV–vis diffuse reflectance spectrum (DRS) and transient photocurrent response test showed the enhanced light harvesting and photo-response. DRS and electron spin resonance (ESR) spectrum confirmed that the enhanced light harvesting could remarkably boost active radical generation. The low recombination rate of free charge carrier and the long lifetime of photon-generated carrier also made great contribution. The lifetime of photon-generated carrier of F0.2-Sn3O4 was 1.38 μs, which was 2.76 times of Sn3O4 (0.50 μs). F0.2-Sn3O4 reduced 95% of 10 ppm Cr(VI) (pH = 7) under light irradiation (400 W metal halogen lamp, light intensity: 148.36 mW/cm2) for 12 min, which was 3.6, 10.2 and 64.5 times higher than that of Sn3O4 (25.83%), C3N4 (9.25%) and commercial TiO2 (1.47%), respectively. F0.2-Sn3O4 could remove 98% of methyl orange within 4 min comparing with commercial TiO2 (30%). The highly removing efficiency of phenols (phenol, bisphenol A and p-chlorophenol) was also obtained. Density functional theory (DFT) calculation, Powder X-ray diffraction (XRD) patterns and DRS revealed that the replacement of F− by O2− enhanced the light harvesting. The work is promising for the synergistic treatment of industrial waste water with organic pollutants (phenols) and Cr(VI).
Currently, air pollution is being exacerbated by rapid social, economic, and industrial development. Major air pollutants include volatile organic compounds (VOCs) and CO. Photocatalytic and ...thermocatalytic technology can be used to convert VOCs and CO into harmless gases effectively. Recently, photothermal synergistic catalysis has aroused much attention because of its higher performance than those of individual photocatalytic and thermocatalytic processes. There have been many reviews on separate photocatalysts and thermocatalysts for the treatment of VOCs and CO, but few reviews have focused on photothermal synergistic catalysis. In this minireview, we concentrate on recent progress into photothermal synergistic catalysis for the efficient removal of VOCs and CO. The treatment of typical VOCs (such as benzene, toluene, ethanol, formaldehyde, acetone, propylene, and propane) and CO are summarized and analyzed. Furthermore, we discuss the use of conventional reactor technology, such as fixed-bed quartz reactors, for VOCs and CO removal. We also discuss the mechanism of the photothermal synergistic catalytic removal of VOCs and CO. Finally, we present perspectives for the photothermal synergistic catalytic removal of VOCs and CO.
This review summarizes the design and fabrication of nanomaterials and their recent progresses with the photothermal synergistic catalysis for efficient removal of VOCs and CO. Furthermore, the typical reactor and mechanism are also analyzed.
Novel B doped BiOCl nanocrystals (B-BiOCl) with exposed (001) facets were fabricated via a facile solvothermal route. The characterization methods of XRD, BET, SEM, TEM, UV–vis DRS, PL, EIS, ESR and ...photocurrent measurement were performed to investigate the physicochemical properties of the B-BiOCl samples. The results indicated that doping B into BiOCl could regulate and control the growth of (001) crystal facet, increase the specific surface areas and enhance the efficiency of charge separation. Hence, the optimal B1.0-BiOCl (atomic ratio of Bi:O:Cl: B is around 27.41: 28.27:25.43:3.55) exhibited significant promoting effect for the degradation of phenol, bisphenol A and rhodamine B than that of pure of BiOCl. The results of radical capturing and ESR analysis confirmed that the O2− radicals played a fatal role in the degradation of organic pollutants. This work could be expected to offer a new insight into design and synthesis of highly efficient photocatalyst with specific exposed facets by doping non-metallic elements.
We designed a novel B-doped BiOCl photocatalyst with exposed (001) facets. This B-doped BiOCl displays significant performance in the degradation of organic pollutants. Display omitted
•Novel B-BiOCl (001) photocatalyst was reported for the first time.•B doping improved the separation efficiency of photogenerated carriers.•B doping enhanced the photocatalytic degradation performance of OPs.•O2− played a fatal role in the degradation of OPs over B-BiOCl photocatalyst.
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