Yidong Hu

Higher visible photocatalytic activities of nitrogen doped In2TiO5 sensitized by carbon nitride

N-doped In(2)TiO(5) modified by carbon nitride (CN) composite (NICN) has been prepared by the pyrogenation of the mixture of urea and In(2)TiO(5) through a polymerizable complex (PC) method. The powder samples were characterized by XRD, FESEM, TEM, UV-vis, and XPS. It is shown by XRD that the precursor sintered at 1000°C is pure and nitrogen dopant does not change the crystal structure of In(2)TiO(5). FESEM and TEM reveal a hole-like morphology of the prepared NICN. With the increase of nitrogen content, the light absorption onset of In(2)TiO(5) shifts from 410 nm to 450 nm, revealing significant narrowing of the band gap. XPS results suggest that only 2.2% of the nitrogen atoms were doped into In(2)TiO(5) through the urea pyrogenation method. Furthermore, the decomposition of Rhodamine B (Rh-B) under visible light reveals that Rh-B can be degraded completely within 20 min and recycling experiments indicate NICN has stable structure and durable photocatalytic activity, suggesting a promising utilization of such photocatalyst under visible light. Finally, an innovative mechanism of N-doped In(2)TiO(5) sensitized by carbon nitride polymer is proposed.

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.

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.

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.

Improved light absorption and photocatalytic activity of Zn,N-TiO2−x rich in oxygen vacancies synthesized by nitridation and hydrogenation

Zn,N-codoped TiO2 rich in oxygen vacancies (Zn,N-TiO2−x) was synthesized by nitridation and hydrogenation of a zinc titanium precursor for the first time, which expands the visible light harvesting region and improves the photocatalytic activity compared to the Zn,N-TiO2 sample without hydrogenation.

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.

Biocoordination Polymer Cross-Linking Structure to a 3D Star Topology Inorganic Photocatalyst Nanocrystal with Improved Hydrogen Evolution Performance

An inorganic photocatalyst with a novel 3D star topology (ST) framework was obtained via multiple cross-linking of biocoordination polymers in one-step solvothermal conditions. It possessesd a large surface area (149.36 m2·g-1), among the highest value of the current reports, and represented the quantum size effect because of its 3D ST structure. The amino acid l-cysteine was introduced into the synthesis system to lead generation of the biometic coordination polymer through the amino acid dehydrate condensation and multiple cross-linking.

A novel visible light-driven silver isocyanate photocatalyst: superior stability enhanced by intrinsic resonance effect

Silver isocyanate (AgNCO), a novel visible-light sensitive semiconductor photocatalyst, is prepared based on an intrinsic resonance effect strategy through a simple precipitation process. The as-prepared photocatalyst exhibits photocatalytic degradation ability under visible light. Importantly, it also shows excellent photocatalytic stability, which is a crucial problem to overcome in Ag-based photocatalysts. The existence of an intrinsic resonance effect and its crystal structure may be the main reasons for the superior photocatalytic stability of the AgNCO photocatalyst. The possible transferred and separated behavior of charge carriers and the reason for outstanding photocatalytic stability are illustrated in detail. This study develops a new design idea for exploiting stable Ag-based photocatalysts under visible light irradiation.