Photocatalytic mechanism of 2.5% Ag/AgIn5S8 photocatalyst.
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•2.5% Ag/AgIn5S8 was fabricated via solvothermal method and further photo-reduction approach.•2.5% Ag/AgIn5S8 heterojunction ...shows the highest visible-light photocatalytic activity.•The degradation pathways of TCHCl and photocatalytic mechanism were proposed.•2.5% Ag/AgIn5S8 can treat real pharmaceutical industry wastewater effectively.
The deposition of Ag nanoparticles (NPs) on semiconductors has been demonstrated to be an efficient route to improve the separation of photogenerated electrons and holes due to plasma resonance effect, but the photocatalytic efficiency of the available Ag-based photocatalysts is still low and far from practical application. In this study, a novel photocatalyst with Ag NPs deposited on the surface of AgIn5S8 (Ag/AgIn5S8) was fabricated via solvothermal method and further photo-reduction approach. The amount of deposited Ag nanoparticles has an obvious effect on the charge separation and visible-light photocatalytic activity of Ag/AgIn5S8, and 2.5% Ag/AgIn5S8 nanocomposites exhibit the highest visible-light photocatalytic activity with 95.3% degradation efficiency of tetracycline hydrochloride (TCHCl) compared with that of the other samples due to the surface plasmon resonance of Ag NPs, proper bandgap of AgIn5S8 and the synergistic effect between them. The main reactive species in TCHCl degradation are OH and O2−. The possible degradation pathway of TCHCl and photocatalytic mechanism of Ag/AgIn5S8 were proposed according to high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) analysis, main reactive species, and conduction band and valence band of AgIn5S8. Moreover, Ag/AgIn5S8 nanohybrids were applied to treat real pharmaceutical industry wastewater, and it was found that the mineralization efficiency and COD removal of real pharmaceutical industry wastewater can reach 56.3% and 77.6%, respectively. The above results indicate Ag/AgIn5S8 photocatalysts have a promising prospect in the treatment of real pharmaceutical industry wastewater.
Z-scheme heterojunction charge transfer mechanisms of CdS/CuInS2.
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•Direct Z-scheme CdS/CuInS2 nanoplates were fabricated by one-pot hydrothermal method.•Z-scheme (1:0.03) CdS/CuInS2 ...exhibits the highest photocatalytic degradation activity.•CdS/CuInS2 shows highly-efficient Cr(VI) reduction without adding hole scavengers.•CdS/CuInS2 can treat real pharmaceutical industry wastewater effectively.•Z-scheme CdS/CuInS2 can maintain long-term activity.
A series of visible-light-driven direct Z-scheme CdS/CuInS2 nanoplates were fabricated by a facile one-step hydrothermal method, and the molar ratio of CdS to CuInS2 was optimized. The highest visible-light photocatalytic degradation activity of Z-scheme (1:0.03) CdS/CuInS2 heterojunction is about 4 times than that of pure CuInS2, which is due to the narrowest band gap, the largest BET surface area, the most efficient charge separation and transfer, and the synergistic effect between CdS and CuInS2. Meanwhile, Z-scheme (1:0.03) CdS/CuInS2 heterojunction also exhibits excellent photocatalytic reduction activity with almost 100% of aqueous Cr(VI) reduction efficiency in absence of hole scavengers after 60 min. The special significance is that Z-scheme (1:0.03)CdS/CuInS2 heterojunction shows excellent stability in five degradation cycles, and can effectively treat real pharmaceutical wastewater with 76.5% COD removal efficiency with aid of H2O2 in 13 h, indicating that Z-scheme CdS/CuInS2 has a promising prospect in real pharmaceutical wastewater treatment.
Single atomic dispersed M‐N‐C (M = Fe, Co, Ni, Cu, etc.) composites display excellent performance for catalytic reactions. However, the analysis and understanding of neighboring M‐N‐C centers at the ...atomic level are still insufficient. Here, FeCo‐N‐doped hollow carbon nanocages (FeCo‐N‐HCN) with neighboring Fe‐N4‐C and Co‐N4‐C dual active centers as efficient catalysts are reported. Spherical aberration‐corrected high angle annular dark‐field scanning transmission electron microscopy, small area (1 nm2) electron energy loss spectroscopy, and X‐ray absorption spectroscopy data analysis and fitting prove the neighboring Fe‐N4‐C and Co‐N4‐C dual active structure in FeCo‐N‐HCN. Experimental tests and density functional theory calculation results reveal that the FeCo‐N‐HCN catalyst displays better catalytic activity than Fe single‐metal catalyst for oxygen reduction reaction (ORR), which is attributed to the synergistic effect of Fe‐N4‐C and Co‐N4‐C dual active centers reducing the reaction energy barriers for ORR. Although the catalytic performance of the FeCo‐N‐HCN catalyst is not comparable to the‐state‐of‐art catalysts reported due to the low metal contents (Fe: 1.96 wt% and Co: 1.31 wt%), these results can refresh the understanding of neighboring M‐N‐C centers at the atomic level and provide guidance for the design of catalysts in the future.
FeCo‐N‐doped hollow carbon nanocages (FeCo‐N‐HCN) with neighboring Fe‐N4‐C and Co‐N4‐C dual active centers are designed and synthesized using a sacrifice template and selective polymerization methods. The FeCo‐N‐HCN presents promising application potential in flexible solid‐state metal–air batteries.
A unique Ag-bridged Ag2O nanowire network/TiO2 nanotube array p–n heterojunction was fabricated by simple electrochemical method. The heterostructures exhibit high photocatalytic activity and ...excellent recycling performance.
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•Ag-bridged Ag2O nanowire network self-stability structure.•Ag2O nanowire network/TiO2 nanotube p–n heterojunction.•High visible light photocatalytic activity.•Highly stable recycling performance.
A unique Ag-bridged Ag2O nanowire network/TiO2 nanotube array p–n heterojunction (Ag–Ag2O/TiO2 NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO2 NT and then were partly oxidized to Ag2O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag2O nanowire network. The Ag–Ag2O/TiO2 NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag–Ag2O self-stability structure and p–n heterojunction permitted high and stable photocatalytic activity of Ag–Ag2O/TiO2 NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag–Ag2O/TiO2 NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO2 NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag–Ag2O/TiO2 NT remained highly stable photocatalytic activity.
Despite the existence of numerous photocatalyst heterostructures, their separation efficiency and charge flow precision remain low due to the poor study on interfacial properties. The photocatalysts ...with confined defects can effectively control the photogenerated carrier migration, but the metastability of such defects considerably decreases the photocatalyst stability. Meanwhile, the introduction of defective region can increase the coordinative unsaturation and delocalize local electrons to promote their interactions with the molecules/ions in that region. The selective growth of modulated heterogeneous interface by defect‐induced strategy may not only increase the stability of defective structures, but also enhance the migration of interfacial charges. Using this method, photocatalytic heterostructures with low contact resistances and intimate interfaces are constructed to achieve the optimal charge migration in terms of efficiency and accuracy. In this work, the point, linear, and planar heterogeneous interfaces and related defect engineering techniques are discussed. Particularly, it is focused on the external, defect‐induced interfacial heterogeneities with various spatial and dimensional configurations, which exhibit modulated and controllable interfacial properties. Furthermore, the main aspects of fabricating photocatalyst heterostructures by the defect‐induced strategy, including the i) controllable generation of defects, ii) advanced characterization methods, and iii) elaborate construction of the minimal interface, are described.
The heterostructures constructed in the defective areas containing new active sites not only solve the metastability problem of defective structures, but also exhibit unique architectures and spatially modulated properties that preserve their high efficiencies. Eventually, the atomic‐level and modulated interfaces can be customized masterly by regulating defect property, transforming a common interface to a defective interface.
Difunctionalization of alkenes has become a powerful tool for quickly increasing molecular complexity in synthesis. Despite significant progress in the area of alkene difunctionalization involving ...the incorporation of a nitrogen atom across the C-C double bonds, approaches for the direct 1,2-carboamination of alkenes to produce linear N-containing molecules are scarce and remain a formidable challenge. Here we describe a radical-mediated oxidative intermolecular 1,2-alkylamination of alkenes with alkyl nitriles and amines involving C(sp
)-H oxidative functionalization catalysed by a combination of Ag
CO
with iron Lewis acids. This three-component alkene 1,2-alkylamination method is initiated by the C(sp
)-H oxidative radical functionalization, which enables one-step formation of two new chemical bonds, a C-C bond and a C-N bond, to selectively produce γ-amino alkyl nitriles.
A high performance sorbent, oligomer-linked graphene oxide (GO) composite, was prepared through simple cross-linking reactions between GO sheets and poly3-aminopropyltriethoxysilane (PAS) oligomers ...as crosslinking agents. The three-dimensional PAS oligomers prevented GO sheets from aggregation, provided foreign molecules with easier access, and introduced a large amount of amino functional groups. The morphology, structure and property of the PAS-GO composite were determined by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourie transform infrared (FTIR), X-ray diffractometer (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The adsorption performance of PAS-GO was investigated in removing Pb(II) ions from water. Compared to 3-aminopropyltriethoxysilane functionalized GO (AS-GO) which was prepared by the direct reaction between 3-aminopropyltriethoxysilane and GO, PAS-GO exhibited much higher adsorptivity toward Pb(II) with the maximum adsorption capacity of 312.5mg/g at 303 K and furthermore the maximum adsorption capacity increased with increasing temperature. The adsorption could be conducted in a wide pH range of 4.0-7.0. Importantly, PAS-GO had a priority tendency to adsorb Pb, Cu and Fe from a mixed solution of metal ions, especially from a practical industrial effluent.
Graphene nanosheets were directly deposited onto a glassy carbon electrode through cyclic voltammetric reduction of a graphene oxide colloidal solution. The resulting electrodes were characterized by ...electrochemical methods and scanning electron microscopy. The application of the graphene modified electrodes in simultaneous determination of hydroquinone and catechol was investigated.
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•Recycling of waste cotton fabrics as an efficient heavy metal adsorbent;.•Fast adsorption kinetics of achieving adsorption equilibrium in five minutes;.•Fix-bed columns can ...efficiently remove heavy metal ions in simulated influent;.•The material can effectively handle the practical industrial effluent.
Massive consumption of cotton fabrics has brought up a serious problem concerning the waste cotton fabrics (WCFs) disposal. It is widely accepted that if WCFs can be reutilized, there will be great business potentials. Herein, we prepared a double network hydrogel based on WCFs and polyacrylamide (Cellulose/PAM DNHs) for heavy metal removal. The DNHs exhibit fast kinetics that sorption equilibrium is achieved in 5min because of the porous and sheet-like laminar structures they possess. The DNHs also illustrate excellent adsorption property and good reusability. The tandem two columns packed with Cellulose/PAM-3 can effectively process simulated and practical wastewater, and the adsorption discrepancy is negligible after three adsorption-desorption cycles. The treatment volumes of simulated wastewater are 172.5 BV (7935mL), 195 BV (8970mL), and 292.5 BV (13455mL) for Cd(II), Cu(II), and Pb(II), respectively. Furthermore, the treatment volumes of practical industrial wastewater reach 42 BV (1932mL) for Cd(II), 63 BV (2898mL) for Cu(II), and 87 BV (4002mL) for Zn(II), Pb(II) and Fe, respectively. This work provides a new avenue for the combination of WCFs reuse and heavy metal removal, which is of great importance to the construction of resource sustainability and environment-friendly society.
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► A novel Fe3O4-RGO–MnO2 nanocomposite is prepared for arsenic removal. ► The nanocomposite has a As (V) capacity of 12.22mgg−1 and As (III) of 14.04mgg−1. ► The nanocomposite has ...oxidation, adsorption and magnetic separation properties. ► Kinetic data were well described by the pseudo-second order model.
Graphite oxide (GO) synthesized from graphite powder was modified with Fe3O4 and MnO2 nanoparticles by a two-step co-precipitation reaction for removing As (III) and As (V) in water. The nanocomposites have a high adsorption capacity and excellent magnetic properties which enable the adsorbent to be separated by an external magnetic field. At pH 7.0, the monolayer adsorption amounts calculated by the Langmuir sorption model were 14.04mgg−1 and 12.22mgg−1 for As (III) and As (V), respectively. The high adsorption capacity was attributed to the large surface of GO which provides more adsorption sites by reducing the aggregation of Fe3O4 and MnO2 nanoparticles. In addition, the MnO2 on the adsorbent surface promoted the oxidation of As (III) to As (V) without addition of other oxidant and simultaneously participated in the adsorption of arsenic with Fe3O4. Furthermore, arsenic adsorption remained stable in a wide pH range 2–10, which is a limitation in most adsorbents. The experimental results suggest that this adsorbent is promising for treating arsenic contaminated natural water
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