Ternary dual S-scheme In2O3/SnIn4S8/CdS heterojunctions for boosted light-to-hydrogen conversion.

Developing artificial S-scheme systems with highly active catalysts is significant to long-term solar-to-hydrogen conversion. Herein, CdS nanodots-modified hierarchical In2O3/SnIn4S8 hollow nanotubes were synthesized by an oil bath method for water splitting. Benefiting from the synergy among the hollow structure, tiny size effect, matched energy level positions, and abundant coupling heterointerfaces, the optimized nanohybrid attains an impressive photocatalytic hydrogen evolution rate of 110.4 µmol/h, and the corresponding apparent quantum yield reaches 9.7% at 420 nm. On In2O3/SnIn4S8/CdS interfaces, the migration of photoinduced electrons from both CdS and In2O3 to SnIn4S8via intense electronic interactions contributes to the ternary dual S-scheme modes, which are beneficial to promote faster spatial charge separation, deliver better visible light-harvesting ability, and provide more reaction active sites with high potentials. This work reveals protocols for rational design of on-demand S-scheme heterojunctions for sustainably converting solar energy into hydrogen in the absence of precious metals.

Ruthenium ion catalytic oxidation depolymerization of lignite under ultra-low dosage of RuCl3 catalyst and separation of the organic products with inorganic salts.

Depolymerization of lignite into valuable chemicals via ruthenium ion catalytic oxidation (RICO) is a potential route for the non-energy utilization of lignite. However, the high cost of the Ru catalyst during depolymerization and the high content of inorganic salts in the product solution limit the development of this route. In this work, RICO depolymerization of lignite was conducted under an ultra-low dosage of RuCl3 catalyst to decrease the usage of the catalyst during the RICO process. Different approaches were attempted to fulfill the separation of benzene polycarboxylic acids (BPCAs) products with the inorganic salts derived from the oxidant NaIO4, including butanone extraction and desalting via crystallization under different temperatures. The results show that lignite can be efficiently depolymerized under the mass ratio of RuCl3/lignite as low as 1/1000 by prolonging the reaction time without decreasing the depolymerization degree and BPCAs yields compared to the commonly used mass ratio of 1/10. Butanone can extract ca. 91% of the total BPCAs in the product solution, and the inorganic salts content (mainly NaIO3) in the extraction solution was as low as 0.19 mg mL-1. A new strategy of first acidification of depolymerization aqueous solution by HCl and then extraction by butanone is proved to be efficient for the separation of BPCAs with inorganic salts. Salting out via crystallization under lower temperature can remove ca. half content of the salts, and the efficiency is inferior to butanone extraction. The low usage of RuCl3 can efficiently decrease the catalyst cost of the RICO process, and butanone extraction can fulfill the enrichment of BPCAs and the separation of BPCAs with inorganic salts. This work is meaningful for the potential application of RCIO depolymerization of lignite for the production of valuable chemicals.

Amino-functionalized NH2-MIL-125(Ti)-decorated hierarchical flowerlike Znln2S4 for boosted visible-light photocatalytic degradation.

Developing novel heterojunction photocatalysts with visible-light response and remarkable photocatalytic activity have been verified to applying for the photodegradation of antibiotics in water environment. Herein, NH2-MIL-125(Ti) was integrated with flowerlike ZnIn2S4 to construct NH2-MIL-125(Ti)@ZnIn2S4 heterostructure using a one-pot solvothermal method. The photocatalytic performance was evaluated by the degradation of tetracycline (TC) under visible light illumination. The optimized NM(2%)@ZIS possesses a photodegradation rate (92.8%) and TOC removal efficiency (58.5%) superior to pristine components, which can be principally attributed to the positive cooperative effects of well-matched energy level positions, strong visible-light-harvesting capacity, and abundant coupling interfaces between the two. Moreover, the probable TC degradation mechanism was also clarified using the active species trapping experiments. This study inspires further design and construction of NH2-MIL-125(Ti) and ZnIn2S4 based photocatalysts for effective removal of antibiotics in water environment.

Extensive solar light harvesting by integrating UPCL C-dots with Sn2Ta2O7/SnO2: Highly efficient photocatalytic degradation toward amoxicillin.

The carbon dots (C-dots) mediated Sn2Ta2O7/SnO2 heterostructures with spongy structure were successfully assembled by simple hydrothermal route. The photocatalytic removal efficiency of amoxicillin (AMX, 20 mg L-1) over C-dots/Sn2Ta2O7/SnO2 was estimated to reach up 88.3% within 120 min simulated solar light irradiating. Meanwhile, the HPLC-MS/MS analysis and density functional theory (DFT) computation were examined to clarify the photo-degradation pathway of AMX. The mechanism investigation proposed that with the modification of C-dots, the photocatalysts improves the utilization of solar energy by harvesting the long wavelength solar light due to their unique up-converted photoluminescence (UCPL). In addition, the porous spongy structure and plenty of tiny C-dots promote the ability of adsorption by enlarged specific surface area. Furthermore, the C-dots mediated Z-type heterojunction of Sn2Ta2O7/SnO2 facilitates the efficient separation and transfer of photo-induced carriers. Our work affords a promising approach for the design of the high-efficient photocatalysts to remedy poisonous antibiotics in aqueous environment.

Carbon dots sensitized 2D-2D heterojunction of BiVO4/Bi3TaO7 for visible light photocatalytic removal towards the broad-spectrum antibiotics.

Focused on the removal of the complicated residual antibiotic in aqueous environment, in this work, a novel carbon dots (C-dots) sensitized 2D-2D heterojunction of BiVO4/Bi3TaO7 were assembled through a simple hydrothermal process. The characteristic by TEM, SEM, and XPS confirmed C-dots evenly anchored on the surface of BiVO4/Bi3TaO7 heterojunction. The as-prepared C-dots/BiVO4/Bi3TaO7 showed superior performance for the degradation of the various antibiotics under visible light illumination. When the concentration of C-dots in the composite is 3 wt.%, the photodegraded rates are obtained to be 91.7%, 89.3%, 87.1%, for tetracycline (TC), amoxicillin (AMX) and ciprofloxacin (CIP), respectively, without significant deactivation during consecutive ten recycle experiments. Furthermore, by assessing the antibiotics mixture solution of TC, AMX and CIP, it is proposed that the prepared samples are potentially effective for the wastewater effluents. A probable mechanism was reasonably proposed. The improved photocatalytic activities could be attributed to the unique construction of the C-dots mediated heterojunction, which could expedite electron migration, improve light harvesting capacity and enhance charge separation efficiency. The present investigation may provide a new perspective to design C-dots mediated heterojunction which could be a potential visible-light-driven photocatalysts for the better practical applications in remediation of broad-spectrum antibiotic residues.

Tetracycline Removal Under Solar Illumination Over Ag3 VO4 /mpg-C3 N4 Heterojunction Photocatalysts.

Ag3 VO4 /mpg-C3 N4 (mesoporous graphitic carbon nitride) heterojunction photocatalysts were prepared by anchoring tiny Ag3 VO4 particles on the nanosheet of mpg-C3 N4 . The prepared Ag3 VO4 /mpg-C3 N4 heterojunctions were used to remove tetracycline (TC), a kind of antibiotics widely released into the aquatic environment under solar irradiation. Compared with pure mpg-C3 N4 and Ag3 VO4 , Ag3 VO4 /mpg-C3 N4 displayed much higher photocatalytic activity (83.2% removal rate within 90 min under visible-light irradiation). Importantly, no apparent deactivation was observed for Ag3 VO4 /mpg-C3 N4 -40 after five cycles, inferring a good reusability. As confirmed by photocurrent measurement and photoluminescence spectra, the excellent photocatalytic property of Ag3 VO4 /mpg-C3 N4 was credit to the electron-hole separation enhancement at the formed heterojunction of two semiconductors. In addition, a possible mechanism and intermediate products for the Ag3 VO4 /mpg-C3 N4 photocatalysts toward the photodegradation of TC in aqueous solution under artificial sunlight radiation were proposed based on the scavengers trapping test, ESR spectra and a high-performance liquid chromatography (HPLC) coupled with mass spectrometer (MS) analysis. This investigation provides a low cost, green and easily practical approach to remove the antibiotics in the aquatic environment.

mpg-C3N4/Ag2O Nanocomposites Photocatalysts with Enhanced Visible-Light Photocatalytic Performance.

To study the photocatalytic activity under visible light irradiation, a series of mesoporous graphitic carbon nitride (mpg-C3N4)/Ag2O photocatalysts were synthesized. The as-prepared photocatalysts were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption Brunauer-Emmett-Teller method (N2-BET), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (DRS), and photoluminescence spectra (PL) methods to determine their phase structure, purity, morphology, spectroscopic and photoluminescence emission performance, respectively. Photocatalytic degradation of methyl orange (MO) aqueous solution under visible-light irradiation indicated that the mpg-C3N4/Ag2O-50 nanocomposite exhibited the best activity. The degradation rate of MO reached to 90.8% in 120 min onto the mpg-C3N4/Ag2O-50 nanocomposite, and as compared with the pure mpg-C3N4 and Ag2O samples, the photocatalytic activity of the mpg-C3N4/Ag2O-50 nanocomposite was greatly enhanced. The enhancement of photocatalytic activity was mainly ascribed to the enhanced visible-light absorption ability and the formation of p-n heterojunctions between counterparts of the nanocomposites, which promoted the generation and separation of charge carriers.