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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]

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]