Construct interesting CuS/TiO2 architectures for effective removal of Cr(VI) in simulated wastewater via the strong synergistic adsorption and photocatalytic process.

Most of the reduction processes for Cr (VI) removal tend to be available only at the acidic condition and the capable extent of pH is limited. Here, we developed a facile strategy for constructing CuS/TiO2 architectures via a facile precipitation process. The as-prepared urchin-like CuS microspheres possessed hierarchical/large porous structure and unique electrical structure, which provided a strong ability to capture the Cr(VI) ions in water. Once CuS microspheres were combined with TiO2 crystals (P25), a surprised high removal efficiency for Cr(VI) was obtained. With optimal molar ratio of CuS:TiO2 (0.72:1), 4.4 and 1.3 times in Cr(VI) removal rate were obtained with respect to pure TiO2 and CuS. The high removal efficiency was induced by the distinct synergistic role of strong adsorption and photocatalytic reduction originated from unique electrical structure in CuS/TiO2 hetero-structure. Moreover, these novel CuS/TiO2 architectures possess promising application for Cr6+ effluents remediation in a wide range of pH and with co-existing anions and cations.

Fabrication and characterization of ZnTiO3/Zn2Ti3O8/ZnO ternary photocatalyst for synergetic removal of aqueous organic pollutants and Cr(VI) ions.

Highly efficient photocatalysts have great development prospects in wastewater treatment, especially in the degradation of organic pollutants and reduction of inorganic heavy metal ions. Herein, a Z-scheme ZnTiO3/Zn2Ti3O8/ZnO ternary photocatalyst was prepared by the solvothermal-calcination method and the influence of the content of tetrabutyl titanate precursor and different reaction temperature on the crystal phase structures, photoelectrochemical properties and photocatalytic activities of the samples were investigated. Due to its unique Z-scheme structure and suitable band gap position, which is favorable for the efficient migration and separation of photo-generated electrons and holes and the improvement of photocatalytic redox reaction capability, the samples show excellent performance for the degradation of organic pollutants and reduction of heavy metal Cr(VI) ions. Based on a series of characterization analyses, a possible Z-scheme photocatalytic mechanism is proposed. This work provides a simple preparation method for fabrication of multivariate heterojunction photocatalyst for degradation of organic pollutants and removal of heavy metal ions.

Photoelectrocatalytic reduction of CO2 to syngas over Ag nanoparticle modified p-Si nanowire arrays.

The solar energy-driven reduction of CO2 and H2O to syngas (H2/CO), an important platform to produce chemicals, is of significance for alleviating greenhouse gas emission and utilizing sustainable solar energy. Here, we report a facile method for the photoelectrocatalytic reduction of CO2 and H2O to syngas over an Ag nanoparticle (NP) modified p-Si nanowire array catalyst. The particle size of Ag significantly influences the activity of CO2 reduction to CO. The H2/CO molar ratio in reduction products can be tuned in the range from 1 to 4 by controlling the size of Ag NPs from 4.2 to 16 nm. The adsorption strength of CO on the catalyst was found to decline with the increase in the size of Ag NPs. The Ag NPs of 8.2 nm, which possess a moderate CO adsorption strength, exhibit the maximum production of CO with the H2/CO ratio of 2/1.

Catalytic transformation of 2,5-furandicarboxylic acid to adipic acid over niobic acid-supported Pt nanoparticles.

The conversion of biomass-derived molecules into adipic acid represents a highly attractive green route for sustainable production of adipic acid, a key monomer of nylon 66 and polyurethane. Here, we report the direct synthesis of adipic acid from 2,5-furandicarboxylic acid, which can be obtained from cellulose-based 5-hydroxymethylfurfural, using a niobic acid-supported platinum catalyst under hydrogen in water.

A facile phase transformation strategy for fabrication of novel Z-scheme ternary heterojunctions with efficient photocatalytic properties.

With increasing pollution of water resources and demand for hydrogen energy, photocatalysis, as a "green chemistry" technology, has attracted great attention. To meet the practical application requirements, photocatalysts should possess enhanced efficiency and be of low cost. Here, a novel Z-scheme ternary ZnTiO3/Zn2Ti3O8/ZnO heterojunction has been prepared by a solvothermal-calcination process. The phase transformation process of the sample can be defined as two processes, dehydration and thermal decomposition (ZnTiO3 → Zn2Ti3O8 + ZnO). The ZnTiO3/Zn2Ti3O8/ZnO heterojunction produced in this facile phase transformation strategy displayed highly efficient photocatalytic performance in water splitting for hydrogen production and pollutant removal, e.g. phenol, dye, and heavy metal Cr(vi). On the basis of the PL spectra, photocurrent response, radical trapping experiments and ESR tests, we found that a nontraditional transport of photoinduced carriers created by a single Z-scheme mechanism played a significant role in the efficient removing of target pollutants and hydrogen generation. This work provides a facile phase transformation approach to construct a Z-scheme semiconductor heterostructure system with high efficiency for hydrogen production and water pollution treatment.

A visible-light-driven core-shell like Ag2S@Ag2CO3 composite photocatalyst with high performance in pollutants degradation.

A series of Ag2S-Ag2CO3 (4%, 8%, 16%, 32% and 40% Ag2S), Ag2CO3@Ag2S (32%Ag2S) and Ag2S@Ag2CO3 (32%Ag2S) composite photocatalysts were fabricated by coprecipitation or successive precipitation reaction. The obtained catalysts were analyzed by N2 physical adsorption, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and photocurrent test. Under visible light irradiation, the influences of Ag2S content and core-shell property on photocatalytic activity and stability were evaluated in studies focused on the degradation of methyl orange (MO) dye, phenol, and bisphenol A. Results showed that excellent photocatalytic performance was obtained over Ag2S/Ag2CO3 composite photocatalysts with respect to Ag2S and Ag2CO3. With optimal content of Ag2S (32 wt%), the Ag2S-Ag2CO3 showed the highest photocatalytic degradation efficiency. Moreover, the structured property of Ag2S/Ag2CO3 greatly influenced the activity. Compared with Ag2S-Ag2CO3 and Ag2CO3@Ag2S, core-shell like Ag2S@Ag2CO3 demonstrated the highest activity and stability. The main reason for the boosting of photocatalytic performance was due to the formation of Ag2S/Ag2CO3 well contacted interface and unique electron structures. Ag2S/Ag2CO3 interface could significantly increase the separation efficiency of the photo-generated electrons (e(-)) and holes (h(+)), and production of OH radicals. More importantly, the low solubility of Ag2S shell could effectively protect the core of Ag2CO3, which further guarantees the stability of Ag2CO3.