Enhanced photocataly tic activity of TiO_2 by surface fluorination in degradation of organic cationic compound

Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.

Fabrication of Z-Scheme WO3/KNbO3 Photocatalyst with Enhanced Separation of Charge Carriers

Z-Schemc photocatalysts as a research locus pertomi strong redox capability and high photocatalytic peribnnance.WO3/KNbO3 photocatalysts were fabricated by ball milling method,and performed higlier photocatalytic activity in liquid degradation(rhodamine B,methylene blue and bisphenol A),compared with WO3 or KNbO3 monomer.This is due to that Z-scheme heterojunction is lonned between WO3 and KNbO3,and the holes photo-excited in valence band of KNbO?are quickly combined with the electrons in conduction band of WO3.The electrons accumulated in conduction band of KNbO3 show high reducibility,thereby reducing O2 to·O 2-,and the holes in valence band of WO3 show high oxidative to oxidize H2O to·OH,respectively.Furthermore,it is proved by means of electron spin resonaiice(ESR)spectra,terephthalic acid photolumiiiescence probing technique(TA・PL),and UV-Vis absorption spectra of nitroblue tetrazolium.This work indicates that the iabrication of Z-scheme structure can improve the photocatalytic activity by efficiently separating the photogenerated electrons and holes in the photocatalytic reaction system,which is helpful to deeply understand the migration mechanism of photoexcited cairier(band-band transfer and Z-scheme transfer)in heterojunction photocatalysts.

Morphology-controlled porphyrin nanocrystals with enhanced photocatalytic hydrogen production

Molecular self-assembly is a natured-inspired strategy to integrate individual functional molecules into supramolecular nanostructured materials through noncovalent bond interactions for solar to fuel conversion.However,the design and engineering of the morphology,size,and orderly stacking of supramolecular nanostructures remain a great challenge.In this study,regular porphyrin nanocrystals with different orderly stacked structures are synthesized through noncovalent self-assembly of Pt(II)meso-tetra(4-carboxyphenyl)porphine(PtTCPP),using surfactants with different electronegativity.The synergy of noncovalent bond interactions between porphyrin molecules,and between porphyrin molecules and surfactants resulted in different molecular packing patterns.Due to the spatial ordering of PtTCPP molecules,the different nanocrystals exhibit both collective optical properties and morphology-dependent activities in photocatalytic hydrogen production.The measurements of the photodeposition of dual cocatalysts showed that the photogenerated electrons and holes selectively aggregated at different active sites,revealing separation pathways and directional transfer of photogenerated electrons and holes in the assemblies.This study provides a new strategy to exert rational control over porphyrin self-assembly nanocrystals for highly efficient water splitting.

Photo-degradation organic dyes by Sb-based organic-inorganic hybrid ferroelectrics

The organic-inorganic hybrid halide compounds have emerged as one of the most promising photoelectric material for their superior optoelectronic properties and hold great prospects for renewable energy substitutes and environmental protection as photocatalysis.Here,we report the optical properties of the Sb-based organic-inorganic hybrid ferroelectric materials:pyridine-4-aminium tetrachloroantimonate((C_(5)H_(7)N_(2))SbCl_(4),sample 1),piperidin-1-aminium tetrachloroantimonate((C_(5)H_(13)N_(2))SbCl_(4),sample 2)and tris(trimethylammonium)nonachlorodiantimonate(((CH_(3))_(3)NH)_(3)Sb_(2)Cl_(9),sample 3),which are a kind of exploited efficient photocatalysts.Samples 2 and 3 exhibit distinct photoelectric respond,which are mainly ascribed to their minor narrow band-gap compared with sample 1.For the ferroelectrics,the intrinsic of spontaneous polarization of sample 3 at room temperature is favourable for the separation of photogenerated electrons and holes within the photorespond process.Moreover,sample 3 shows the highest efficiency of photo-decomposed Rhodamine B(90.2%within 80 min)and Methyl Orange(MO)(97.4%within 50 min),thanks to the photo-excited electrons and holes promoting the formation of oxidative radical species during the photo-redox progress.These findings prove that the development of a novel Sbbased organic-inorganic hybrid halide compounds with good stability in the degradation of organic dyes paves a way to designing new photocatalyst.