Zhonghui Han

A Novel Mesoporous Single-Crystal-Like Bi2WO6 with Enhanced Photocatalytic Activity for Pollutants Degradation and Oxygen Production

The porous single-crystal-like micro/nanomaterials exhibited splendid intrinsic performance in photocatalysts, dye-sensitized solar cells, gas sensors, lithium cells, and many other application fields. Here, a novel mesoporous single-crystal-like Bi2WO6 tetragonal architecture was first achieved in the mixed molten salt system. Its crystal construction mechanism originated from the oriented attachment of nanosheet units accompanied by Ostwald ripening process. Additionally, the synergistic effect of mixed alkali metal nitrates and electrostatic attraction caused by internal electric field in crystal played a pivotal role in oriented attachment process of nanosheet units. The obtained sample displayed superior photocatalytic activity of both organic dye degradation and O2 evolution from water under visible light. We gained an insight into this unique architectures impact on the physical properties, light absorption, photoelectricity, and luminescent decay, etc., that significantly influenced photocatalytic activity.

Preparation of 1D cubic Cd0.8Zn0.2S solid-solution nanowires using levelling effect of TGA and improved photocatalytic H2-production activity

The one-dimensional (1D) cubic Cd0.8Zn0.2S solid-solution nanowires are first prepared by the “levelling effect” of thioglycolic acid (TGA) in a solvothermal process. It exhibits the enhanced transfer and separation efficiency of carriers to improve the photocatalytic H2-production activity. TGA not only serves as the sulphur source but also plays a template medium agent role. Furthermore, no TGA selectivity for diverse solvents to prepare 1D Cd0.8Zn0.2S solid solutions suggests that it also may be extended to the preparation of other 1D metal sulphide solid solutions in diverse solvents.

Doping La into the depletion layer of the Cd0.6Zn0.4S photocatalyst for efficient H2 evolution

We report a novel strategy for the enhancement of photocatalytic H2 evolution by doping La into the depletion layer of Cd0.6Zn0.4S (CZS: x% La). The apparent quantum yield of the CZS: 2% La photocatalyst at 350 nm is up to 93.3%, which is extremely high for solar water splitting even compared with the noble metal cocatalyst systems. This work may contribute to the design and construction of materials with outstanding capability for charge separation and hence improve the properties of the materials for various applications.

Recent advances in rare-earth elements modification of inorganic semiconductor-based photocatalysts for efficient solar energy conversion: A review

Abstract This review focused on rare-earth elements containing inorganic semiconductor photocatalysts for efficient solar energy conversion. We also summarized the recent progress in the modification of the transition metal oxides and mixed oxides with rare earth ions. In the first section, we surveyed a variety of rare-earth elements modified TiO2 photocatalysts. Attributed to the modification with rare-earth elements, phase transformation of TiO2 from anatase to rutile was inhibited. Furthermore, the light-absorbing property of the TiO2 modified with rare-earth elements was also enhanced. In the second section, we summarized the effects of rare-earth elements on the modification of transition metal mixed oxides. It was believed that the corner-shared octahedral units in the form of networks, chains and slabs within the mixed oxide lattice were essential for the enhancement of the photocatalytic activity. In the last section, the strategy for the design of NIR or IR response upconversion composite photocatalysts was also discussed.

Fabrication of {010} facet dominant BiTaO4 single-crystal nanoplates for efficient photocatalytic performance

The facets of nano-photocatalysts play an important role in their photocatalytic activity. Here, we prepared {010} facet dominant BiTaO4 single-crystal nanoplates, which can both split water into H2 and decompose organic dyes into non-toxic small molecules. UV-vis DRS, XPS valence band and Mott–Schottky measurements and DFT calculations demonstrated that the up-shift of the conduction band minimum significantly increased the reduction ability of photogenerated electrons, thus leading to highly efficient photocatalytic performance. Typical bulk BiTaO4 does not have any water splitting capability and shows poor photodegradation activity. However, the {010} facet dominant BiTaO4 single-crystal nanoplates realize the H2 evolution of BiTaO4 and improve the photodegradation activity 52 times via conduction band minimum up-shift. The understanding of the facet effect on photocatalysis will provide valuable instructions for the design of other photocatalysts.

Oxygen functional groups induced formation of Cu2O nanoparticles on the surface of reduced graphene oxide

We provide a new insight into the relationship between the oxygen functional groups of graphene oxide (GO) and the formation of nanoparticles on the graphene surface. Furthermore, a mechanism of the interaction between cations and graphene oxide in aqueous solution was proposed.

Whole-Visible-Light Absorption of a Mixed-Valence Silver Vanadate Semiconductor Stemming from an Assistant Effect of d–d Transition

Wide-light absorption is important to semiconductors exploited in many applications such as photocatalysts, photovoltaic devices, and light-emitting diodes, which can effectively improve solar energy utilization. Especially for photocatalysts, the development and design of new semiconductors that harvest the whole-visible-light region (λ = 400-800 nm) is rarely reported, which is still a tremendous challenge up to now. Here we realize whole-visible-light absorption up to 900 nm for a semiconductor by means of construction of a mixed-valence Ag0.68V2O5, which results from an assistant effect of d-d transition. Ag0.68V2O5 serving as a photocatalyst obviously exhibits photoelectrochemical and photocatalytic properties. Our results provide a brand-new feasible design strategy to broaden the light absorption of semiconductors and highlight a route to further make the best use of the full solar spectrum.

A thin empty-shell bismuth tungstate hierarchical structure constructed by the acid sculpture effect with improved visible-light photocatalytic activity

A thin empty-shell bismuth tungstate hierarchical structure, which is composed of ultrathin nanosheets (∼14.0 nm), is constructed using the acid sculpture effect without any templates or surfactants by a facile hydrothermal process. It results in a large specific surface area and abundant pores through the inside and outside of the thin empty-shell, which shortens transport distance of organic molecules and provides plenty of reaction active sites for improving photocatalytic activity. The thin empty-shell bismuth tungstate hierarchical structure can more effectively remove colored RhB and colorless phenol in aqueous solutions relative to typical bismuth tungstate. The possible evolved mechanism of the thin empty-shell hierarchical structure and the photocatalytic reaction mechanism are discussed in detail.

Non-integer induced spontaneous polarization of highly efficient perovskite-based NBTO SCN photocatalysts

Perovskite oxides and their derivative photocatalysts are promising candidates for highly efficient solar energy conversion and environmental remediation. Herein, we proposed a non-integer induced spontaneous polarization of highly efficient perovskite-based NBTO SCN photocatalysts. The experimental and theoretical results demonstrate that the Na0.5Bi2.5Ta2O9 single-crystal nanoplates (NBTO SCNs) with exposed {001} facets show more superior photocatalytic efficiency in hydrogen evolution and pollutant degradation than conventional integer NaTaO3 and BiTaO4. The non-integer structure (mixed A-site cations Na+ or Bi3+) of NBTO SCNs possesses giant spontaneous polarization along the c-axis. Therefore, the generated carriers can easily diffuse along the polarization direction to the opposite surfaces of catalysts, and thus significantly increase the photocatalytic activities of NBTO SCNs.

In situ formation of metal CdxZn1−xS nanocrystals on graphene surface: a novel method to synthesise sulfide–graphene nanocomposites

Herein, CdxZn1−xS–graphene composites were prepared via an in situ growth solvothermal process using sulfur–graphene composites as precursor for the first time. The as-prepared samples exhibit efficient photocatalytic activities, including the production of H2 as well as the photo-oxidation of methylene blue dye under visible light irradiation.