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Abstract: Ag–AgBr was deposited onto mesoporous alumina (MA) and titanium-doped MA by a deposition–precipitation method. The photocatalytic activity and the dissolution of Ag+ from different catalysts were investigated during the photodegradation of 2-chlorophenol (2-CP) and phenol in ultrapure water and tap water with visible-light irradiation. With the increase in doped titanium, the Ag+ dissolution decreased with a decrease in the photocatalytic activity. Ag–AgBr/MA-Ti1 was considered the better catalyst for practical applications because its Ag+ dissolution was minimal (0.4mgL−1 in ultrapure water and 5μgL−1 in tap water), although its photoactivity was slightly less than that of Ag–AgBr/MA. The dissolution of Ag+ was related to a charge–transfer process based on the study of cyclic voltammetry analyses under a variety of experimental conditions. The results suggested that several types of anions in the water, including CO3 2−, SO4 2−, and Cl−, could act as electron donors that trap the photogenerated holes on Ag nanoparticles to facilitate electron circulation; this would decrease the release of Ag+. Our studies indicated that the catalyst had a higher activity and stability in water purification. [Copyright &y& Elsevier]

[Display omitted] • WO 3 @NiFe-LDHs photoanode was prepared by an economical electrochemical depositing method. • WO 3 @NiFe-LDHs shows excellent PEC degradation and TOC removal of TC. • LDHs formed a hetero-junction with WO 3 to improve interfacial charge separation. • TC was captured by LDHs to strengthen direct charge transfer and light absorbance. • This work offered a potential concept of using pollutants for photoanode design. A novel WO 3 @NiFe-LDHs photoanode was successfully synthesized by electrochemical depositing NiFe-LDHs nanosheets array on the surface of nanoplate WO 3 photoanode, in which NiFe-LDHs nanosheets formed a hetero-junction with WO 3 and offered mass transfer sites to improve the bulk and interfacial charge separation of WO 3 @NiFe-LDHs photoanodes. In addition, TC was captured by NiFe-LDHs nanosheets, which not only facilitated the direct charge transfer for TC degradation, but also induced TC to be photo-sensitizer to enhance the light absorbance of WO 3 @NiFe-LDHs photoanode. Moreover, NiFe-LDHs nanosheets acted as surface catalytic sites for accelerating the water activation to generate highly oxidizing •OH. Therefore, the optional WO 3 @NiFe-LDHs2.5 photoanode displayed the highest PEC removal of TC with a degradation percentage of 92.3% and total organic carbon removal of 70.4% at 0.6 V (vs Ag/AgCl) bias, and showed higher photocurrent density compared with pristine WO 3 photoanode. Furthermore, WO 3 @NiFe-LDHs photoanode showed favorable stability in the PEC degradation process, and TC was finally mineralized into CO 2 , H 2 O and some small molecular products. This work provides a deep insight on the modification of interfacial reaction to enhance the PEC degradation performance, which offered a potential route for designing PEC system with the concept of treating pollution with pollution. [ABSTRACT FROM AUTHOR]

Two kinds of ionic fluorocarbon block copolymers were synthesized by atom transfer radical polymerization (ATRP) and polymer-analogue reaction. Fluorinated block copolymers (PTF and PSF) were prepared by ATRP of 2-[(perfluorononenyl)oxy]ethyl methacrylate (FNEMA) using bromine-end-capped poly(tert-butyl acrylate) (PtBA-Br) and poly(styrene) (PS-Br) as macroinitiators, respectively, and were characterized by GPC, FT-IR and 1H-NMR. The former (PTF) was followed by hydrolysis of the tert-butyl groups to carboxylic groups, while the latter was followed by sulfonation of the styrene units to sulfonic groups. The degree of hydrolysis of PTF and the level of sulfonation of PSF were measured by 1H-NMR and elemental analysis, respectively. [Copyright &y& Elsevier]

• Both Bi vacancies and Bi0 were introduced into Bi2MoO6 to produce Bi0-Bi2-δMoO6. • Bi0-Bi2-δMoO6 was highly effective for pollutants removal under visible light. • Bi vacancies enlarged the band gap for efficient charge separation. • The electron transfer from Bi2-δMoO6 to Bi0 was promoted by their strong interaction. • O2•− generated on surface Bi0 and holes on Bi2-δMoO6 were the main active species. Bi vacancies and Bi0 containing Bi 2 MoO 6 (Bi0-Bi 2- δMoO 6) was synthesized by a facile chemical reduction method. The visible-light-driven photoactivity of Bi 2 MoO 6 was enhanced by nearly 7 times due to the synergy of Bi vacancies and Bi0. Based on the characterization of XRD, HRTEM, XRF, XPS, Raman, FTIR and PL, Bi vacancies and Bi0 coexisted in the crystal lattice of Bi 2 MoO 6 , and a strong interaction between Bi0 and Bi 2- δMoO 6 was observed. Bi vacancies were proved to enlarge the band gap to promote the separation of photogenerated electron-hole pairs, and Bi0 can act as an electron trap to accelerate the charge transfer by its strong interaction with Bi 2- δMoO 6 , resulting in the high photoactivity of Bi0-Bi 2- δMoO 6 for the degradation of various organic pollutants under visible light. By the studies of ESR and other experiments, the charge transfer process was clarified that the fast separated electrons from Bi 2- δMoO 6 by Bi vacancies were transferred to Bi0 and further reacted to produce O 2 •−, and thus the photoexcited holes were accelerated to transfer to the surface of Bi 2- δMoO 6 to oxidize water into more •OH and directly degrade organic pollutants in water. [ABSTRACT FROM AUTHOR]

Few-layered Bi 4 O 5 I 2 nanosheets (FL-Bi 4 O 5 I 2) were synthesized by intergrowth with Bi 2 O 2 CO 3 under room temperature. The photoactivity of FL-Bi 4 O 5 I 2 was 2.5 and 9.5 times higher than that of Bi 4 O 5 I 2 nanoflakes (NF-Bi 4 O 5 I 2 , about 30 nm thickness) and standard visible-light-driven N-TiO 2 , respectively. Moreover, FL-Bi 4 O 5 I 2 exhibited a wide pH application range (3.0 – 10.0) and excellent photostability. The characterization results showed FL-Bi 4 O 5 I 2 was consisted of 5 – 8 layers with thickness of 4 – 7 nm and enclosed by {1 0 − 1} facets. The ultrathin characteristics could accelerate the charge transfer to the surface due to the shortened transport distance. Compared to NF-Bi 4 O 5 I 2 , surface oxygen vacancies and the more negative CB potential were formed on FL-Bi 4 O 5 I 2. The photogenerated electrons were confirmed to be captured by surface oxygen vacancies to effectively reduce surface adsorbed O 2 into HO 2 •/O 2 •–, leaving more h+ to oxidize organic pollutants. This process was further facilitated by the more negative CB potential of FL-Bi 4 O 5 I 2 , resulting in the highly efficient removal of pollutants. [Display omitted] • Few-layered Bi 4 O 5 I 2 were formed by intergrowth with Bi 2 O 2 CO 3 at room temperature. • FL-Bi 4 O 5 I 2 was enclosed by {1 0−1} facets with surface oxygen vacancies. • Surface oxygen vacancies as electron traps promoted the efficient reduction of O 2. • HO 2 •/O 2 •– and holes were involved in the photocatalytic degradation process. • Organic pollutants were efficiently degraded by the surface adsorption and oxidation process. [ABSTRACT FROM AUTHOR]

Simultaneous solar hydrogen production and organics degradation is achieved by an unassisted, hybrid tandem photocatalytic fuel cell based on a highly-active silicon-doped TiO 2 nanorod array with enhanced electronic properties. • A high-active STNR with homogenously distributed silicon in TiO 2 matrix is prepared. • A notably enhanced J sc of ˜0.76 mA cm−2 at 0.2 V vs Ag/AgCl is achieved for STNR. • A HTPFC is assembled by adhering Si PVC at the back of STNR as monolithic photoanode. • A removal ratio of 94.3% for TC is obtained by HTPFC in 1.5 h operation. • An H 2 generation rate of ˜28.8 μmol h−1 cm−2 is also achieved during degradation. A novel, unassisted, hybrid tandem photocatalytic fuel cell (HTPFC) is constructed by adhering a silicon solar cell (SSC) to the back of a highly-active silicon-doped TiO 2 nanorod array (STNR) for efficient solar hydrogen production coupled with organic compound degradation. The STNR with vertically arranged nanorods is prepared by a facile hydrothermal method and has improved charge transport properties and donor density due to the homogenously distributed silicon in the TiO 2 matrix. As a result, the STNR has a notably enhanced photocurrent density that is as high as ˜0.76 mA cm−2 at 0.2 V vs Ag/AgCl, which is ˜271% of the photocurrent density of undoped sample. By combining the intriguing features of the STNR and SSC, the HTPFC shows a superior performance for tetracycline degradation and hydrogen production, with a removal ratio of 94.3% after 1.5 h of operation and an average hydrogen generation rate of ˜28.8 μmol h−1 cm−2. Compared to conventional PFCs, HTPFCs have improved light absorption and charge transfer, owing to the synergistic effect between the STNR and SSC. The results also indicate that the HTPFC is highly flexible, adaptable, and stable when treating wastewaters with various organics, and a wide range of pH values and salinities. [ABSTRACT FROM AUTHOR]

• Multiple vacancy associates were introduced by constructing porous β-Bi 2 O 3 -{220}. • Porous β-Bi 2 O 3 -{220} was highly effective for pollutants removal under visible light. • Multiple vacancy associates enhanced surface polarization for efficient charge separation. • The electron transfer from pollutants to the catalyst was promoted by their strong interaction. • HO 2 and holes were confirmed to be the main active species. Porous β-Bi 2 O 3 with highly exposed {220} facets was fabricated for the first time and the formation of surface multiple Bi-O vacancy associates was confirmed by the photoluminescence, positron annihilation spectra, and theoretical calculations. Compared with traditional nonporous β-Bi 2 O 3 -{201}, the photocatalytic rate of porous β-Bi 2 O 3 -{220} was more than twice faster and the photoconversion efficiency increased by 20 times. And various refractory organic pollutants can be effectively degraded and mineralized under visible light. Multiple Bi-O vacancy associates were demonstrated to change electronic structure and enhance the polarization of the related atoms and orbitals. The photogenerated charge separation and transfer was thus improved to produce more surface active species. Simultaneously, the electron transfer from pollutants to the catalyst was found to be accelerated, finally leading to the outstanding photocatalytic performances of porous β-Bi 2 O 3 -{220}. These findings provide useful insights into the development of visible-light-driven photocatalysts for water purification. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) has enormous potentials for photocatalysis, yet it only possesses moderate activity because of excitonic effects and sluggish charge transfer. Here, we develop a novel two-dimensional g-C 3 N 4 /WO 3 /MoS 2 (CWM) ternary nanocomposite through a facile co-calcination and a hydrothermal process to reach a highly-efficient photocatalyst for organic pollutant elimination under visible light. The WO 3 and MoS 2 nanoparticles were dispersed on the ultra-thin g-C 3 N 4 nanosheets, in which the electronegative g-C 3 N 4 facilitates formation of oxygen vacancies in WO 3. Compared to pure g-C 3 N 4 , WO 3 , and binary composites, CWM exhibited higher photocatalytic activities for various organic pollutants removal under visible light irradiation. For instance, the CWM showed a removal ratio of ∼99% for RhB after only 10 min irradiation of visible light (λ > 420 nm) and nearly 100% for ciprofloxacin after 2 h of operation. The results showed that OH radicals are the main active species for organic degradation, which suggests a direct Z-scheme heterojunction in CWM that improved spatial separation of charge carries. Furthermore, the collection of electrons is significantly enhanced by MoS 2 for oxygen reduction reaction, and the increased oxygen vacancies of WO 3 further enhanced the separation of electron-hole pairs; therefore, it led to an effective suppression of charge carriers recombination. The above synergistic effects of ternary photocatalyst result in higher photocatalytic oxidation performance for wastewater treatment compared with pure WO 3 , g-C 3 N 4 and their binary composites. Efficiently improved organics and dyes degradation system is acquired using a 2-D g-C 3 N 4 /WO 3 /MoS 2 ternary nanocomposite which has improved spatial separation of charge carries and facilitated collection of electrons under visible light. Image 1 • 2-D CWM was constructed through a facile co-calcination and a hydrothermal process. • Electronegative g-C 3 N 4 facilitates the formation of oxygen vacancies in WO 3. • High rates of degradation are obtained for various organic contaminants under visible light. • The CWM shows Z-scheme heterostructure in photogenerated charges separation. • MoS 2 further hinders the charge recombination by consuming electrons for ORR. [ABSTRACT FROM AUTHOR]