Yansong Zhou

Facile Approach to Synthesize g-PAN/g-C3N4 Composites with Enhanced Photocatalytic H2 Evolution Activity

Novel composites consisting of graphitized polyacrylonitrile (g-PAN) nanosheets grown on layered g-C3N4 sheets were synthesized through a facile one-step thermal condensation of PAN and melamine for the first time. Photoluminescence spectroscopy and the photoelectrochemical measurements reveal that g-PAN nanosheets act as effective electron transfer channels to facilitate charge carrier separation in g-PAN/g-C3N4 composites. The g-PAN/g-C3N4 composites exhibit significantly enhanced visible-light photocatalytic performance for H2 evolution over pristine g-C3N4. The 5.0 wt % g-PAN/g-C3N4 composite has optimal H2 evolution rate of 37 μmol h(-1), exceeding 3.8 times over pristine g-C3N4. We have proposed a possible mechanism for charge separation and transfer in the g-PAN/g-C3N4 composites to explain the enhanced photocatalytic performance.

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.

ZIF-8 derived carbon (C-ZIF) as a bifunctional electron acceptor and HER cocatalyst for g-C3N4: construction of a metal-free, all carbon-based photocatalytic system for efficient hydrogen evolution

A ZIF-8 derived carbon (C-ZIF)/g-C3N4 composite was constructed for the first time through facile thermal condensation of a zeolitic imidazolate framework (ZIF-8) and melamine. The obtained C-ZIF/g-C3N4 composite exhibited an obviously enhanced photocatalytic H2 production rate compared to pure g-C3N4 under visible light irradiation. The 1 wt% C-ZIF/g-C3N4 composite without loading the Pt co-catalyst showed 36.2 times higher H2 evolution rate than that of pure g-C3N4, which is even 2.8 times higher than that of Pt/g-C3N4 (the state-of-the-art g-C3N4-based photocatalyst). It was revealed by photoluminescence spectroscopy, time-resolved fluorescence spectroscopy and electrochemical impedance spectroscopy that the formed C-ZIF and g-C3N4 junction could promote quick charge carrier separation and transfer. The C-ZIF not only acted as an effective electron acceptor, but also functioned as an efficient hydrogen evolution reaction (HER) cocatalyst to promote photocatalytic hydrogen evolution. Our work provides an effective way for the development of metal-free, all carbon-based photocatalysts for H2 evolution.

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.

An Amorphous Noble‐Metal‐Free Electrocatalyst that Enables Nitrogen Fixation under Ambient Conditions

N2 fixation by the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is regarded as a potential approach to achieve NH3 production, which still heavily relies on the Haber-Bosch process at the cost of huge energy and massive production of CO2 . A noble-metal-free Bi4 V2 O11 /CeO2 hybrid with an amorphous phase (BVC-A) is used as the cathode for electrocatalytic NRR. The amorphous Bi4 V2 O11 contains significant defects, which play a role as active sites. The CeO2 not only serves as a trigger to induce the amorphous structure, but also establishes band alignment with Bi4 V2 O11 for rapid interfacial charge transfer. Remarkably, BVC-A shows outstanding electrocatalytic NRR performance with high average yield (NH3 : 23.21 μg h-1  mg-1cat. , Faradaic efficiency: 10.16 %) under ambient conditions, which is superior to the Bi4 V2 O11 /CeO2 hybrid with crystalline phase (BVC-C) counterpart.

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.

Synthesis of metal oxide nanosheets through a novel approach for energy applications

This work describes an ultra-facile and generalized route to synthesize metal oxide nanosheets including TiO2, Fe2O3, Co3O4, ZnO, and WO3 with large area. Compared with conventional routes, the route here is ultra-facile to prepare scalable metal oxide nanosheets for energy applications.

Construction of α–β Phase Junction on Bi4V2O11 via Electrospinning Retardation Effect and Its Promoted Photocatalytic Performance

The creation of a phase junction structure in photocatalysts is a wise approach to promote photocatalytic performance, as phase junctions possess the potential to inhibit the recombination of photoinduced charge carriers. Here, Bi4V2O11 nanofibers with an α-β phase junction are fabricated via electrospinning with subsequent calcination. Electrospinning offers the opportunity to keep α-Bi4V2O11 from transforming into β-Bi4V2O11 completely due to an electrospinning retardation effect, leading to the formation of an α-β Bi4V2O11 phase junction. Furthermore, the α-β Bi4V2O11 phase junction realizes a well-established type-II band alignment. Photoelectrochemical measurements and photoluminescence spectroscopic investigations demonstrate that the phase junction structure has a significant impact on the separation and transfer of photogenerated electrons and holes. Thus, the α-β phase junction on Bi4V2O11 holds the key to achieving promoted efficiency in the photocatalysis process.