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The aggregate structures of photocatalyst particles are critical for their light absorption and scattering properties and thus significantly impact the photocatalytic performance toward solar hydrogen production. Herein, taking P25 TiO 2 nanoparticles as model photocatalysts, we calculate the optical properties of the aggregates of nanoparticles with the Discrete Dipole Approximation (DDA). A scattering phase function, which can reveal and predict the structural information of photocatalyst particles, is accordingly obtained. Specifically, it is found that the forward scattering is dominant when light is scattered on the particles, and this scattering mode becomes more intense with the increment of the particle size. Our results show that the scattering phase function is also in agreement with the Rayleigh-Gans-Debye (RGD) approximation. • Clusters of TiO 2 nanoparticles are established via fractal aggregation models. • Scattering properties are calculated via Discrete Dipole Approximation. • Forward-scattering dominates the phase function in modeling photocatalysis. • Phase functions agree with the prediction of Rayleigh-Gans-Debye approximation. [ABSTRACT FROM AUTHOR]

Abstract: A series of Mn2+ doped CdS photocatalysts were prepared by a co-precipitation method and characterized by XRD, DRS, TEM, and XPS techniques. While the band gap, crystal phase and the morphology of CdS nanocrystal were not found to be affected noticeably by Mn2+ doping, there was an optimal Mn2+ doping content of wt 0.5% where the hydrogen production was more than doubled compared to pure CdS. Calculations of density functional theory (DFT) with plane waves and pseudopotentials were used to characterize the doping effect of Mn in cubic CdS. It is assumed that Mn2+ serving as shallow trapping sites can separate e−/h+ pairs at surface of nanosized CdS, so as to greatly reduce their surface recombination and which in turn leads to improved hydrogen yield. [Copyright &y& Elsevier]

Abstract: (CuIn) x Zn2(1-x)S2 (x = 0.01–0.5) microspheres were prepared by a simple hydrothermal method. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Visible diffuse reflectance spectra (UV–Vis), Raman scattering spectra and Brunauer-Emmett-Teller (BET) surface area measurement. It was found that the (CuIn) x Zn2(1-x)S2 samples formed solid solution only in the presence of surfactant cetyltrimethylammonium bromide (CTAB). CTAB enabled the increase of the surface area for the (CuIn) x Zn2(1-x)S2 solid solutions. Diffuse reflection spectra of the solid solutions shifted monotonically to long wavelength side as the value of x increased. The photocatalytic H2 evolution activity under visible-light irradiation of the solid solutions was evaluated. The result showed that the activity depended on their corresponding compositions closely. Ru (1.5 wt%)-loaded (CuIn)0.2Zn1.6S2 showed the highest photocatalytic activity of 198.09 μmol h−1 under visible-light irradiation, and the apparent quantum yield amounted to 15.45% at 420 nm. Furthermore, the density functional theory (DFT) calculations showed that the solid solution with the ration of ZnS and CuInS2, 6:1, was a direct band gap semiconductor. The valence band consisted of the hybrid orbital of S 3p and Cu 3d and the conduction band consisted of In 5s5p orbital mixed with Zn 4s4p. The energy band structure resulted in the visible-light response of the solid solution, and affected its photocatalytic performance. [Copyright &y& Elsevier]

Abstract: Cubic and rhombohedral ZnIn2S4 were synthesized by thermal sulfidation of Zn–In mixed oxide precursor in H2S atmosphere at different temperatures. Cubic ZnIn2S4 was obtained when Zn–In mixed oxide precursor was sulfurized at 400°C. With sulfidation temperature increasing from 400 to 800°C, the crystal phase of ZnIn2S4 gradually turned from cubic to rhombohedral, which was demonstrated by different analysis techniques such as XRD, Raman, SEM, etc. UV–vis absorption spectra indicated that cubic ZnIn2S4 displayed better light absorption property than rhombohedral ZnIn2S4, with band gaps calculated to be 2.0 and 2.5eV, respectively. However, under visible light irradiation, rhombohedral ZnIn2S4 photocatalyzed H2 evolution from aqueous sodium sulfite/sulfide solution efficiently, whereas cubic ZnIn2S4 was not active for this reaction. The photoluminescence property revealed the different dynamics of photogenerated carriers, which made a predominant contribution to the increasing photocatalytic performances of ZnIn2S4 with crystal phase turning from cubic to rhombohedral. [Copyright &y& Elsevier]