Pt-Substituted polyoxometalate modification on the surface of low-cost TiO2 with highly efficient H2 evolution performance.

In this study, Pt-substituted polyoxometalate was first modified on the surface of commercially available TiO2, forming an efficient photocatalyst with high reactivity for hydrogen evolution. During the photocatalytic process, Pt-polyoxometalates not only increase the mobility rate of electrons but also improve the separation efficiency of photoinduced electrons and holes. After photoreduction, the in situ generated Pt0 species are anchored on the surface of polyoxometalate anion, which prevents further agglomeration. Then, the in situ formed Pt0 species and polyoxometalates synergistically promote the efficiency of photoinduced electron transfer from TiO2 to the protons adsorbed on the Pt0 surface. Although the content of Pt0 in the nanocomposite is only 0.6%, the photocatalytic hydrogen production rate reaches 5.6 mmol g-1 h-1 and remains stable at 4.5 mmol g-1 h-1 after the continuous catalytic process. Due to the modification of TiO2 by Pt-substituted polyoxometalate, this nanocomposite represents a practical model that possesses highly efficient photoelectric conversion performance. The presented work not only extends the family of new TiO2-polyoxometalate-based materials but also takes a further step toward the practical application of commercial TiO2 in photocatalytic hydrogen production.

In situ electrochemical assessment of cytotoxicity of chlorophenols in MCF-7 and HeLa cells.

An in situ electrochemical method was used to assess the cytotoxicity of chlorophenols using human breast cancer (MCF-7) and cervical carcinoma (HeLa) cells as models. On treatment with different chlorophenols, the electrochemical responses of the selected cells, resulting from the oxidation of guanine and xanthine in the cytoplasm, indicated the cell viability. In addition, the in situ in vitro electrochemical method was further compared with the traditional MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. Although similar cytotoxicity data were obtained from both methods, the effective concentrations of chlorophenols that inhibited 50% cell growth (EC50 values) from the electrochemical method were only slightly lower than those from the MTT assay. These results indicate that the in situ in vitro electrochemical method paves a simple, rapid, strongly responsive, and label-free way to the cytotoxicity assessment of different chlorophenol pollutants.