Chade Lv

A facile approach to construct BiOI/Bi5O7I composites with heterostructures: efficient charge separation and enhanced photocatalytic activity

A series of BiOI/Bi5O7I composite photocatalysts with heterostructures was successfully synthetized through a facile hydrothermal method. Attributed to the heterostructure between BiOI and Bi5O7I, photogenerated electrons and holes can be separated efficiently. The photocatalytic activity of the as-prepared samples was evaluated through the MO degradation reaction. The removal rate of MO was up to 93% after 40 min under visible light (λ ≥ 400 nm) irradiation, while the photocatalytic activity showed no decay after 3 cycles. Furthermore, the photocatalytic mechanism of MO degradation over the BiOI/Bi5O7I composite photocatalyst was investigated by taking TA, H2O2 and EDTA as probes. The experimental results indicate that the enhanced photocatalytic performance is attributed to the synergistic effect of photogenerated holes and superoxide radicals. The excellent activity and photostability reveal that the BiOI/Bi5O7I composite photocatalyst is a promising visible-light-response photocatalyst with potential applications in the field of water treatment.

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.

Controllable synthesis of In2O3 octodecahedra exposing {110} facets with enhanced gas sensing performance

In2O3 octodecahedra have been successfully prepared by annealing the 18-facet In(OH)3 precursor. The as-prepared In2O3 polyhedra inherit the morphology of the In(OH)3 precursor and expose twelve {110} and six {100} facets. Gas sensing tests show that octodecahedron-based In2O3 sensor exhibits a sensitivity of 610 to 1000 ppm ethanol, which is 2.3-fold and 5.5-fold enhancement compared with cube- and particle-based sensor, respectively. The XPS results demonstrate that the {110} and {100} facets of In2O3 octodecahedra provided more oxygen vacancies than either the cubes exposing only {100} facets or the irregular particles. More oxygen vacancies would contribute to the enhancement of gas sensing performance. The crystal facet analysis of In2O3 octodecahedra show that high energy {110} facets could be easier to form oxygen vacancy than that of {100} facets, which could be the main reason for high gas sensing property. This finding will open a door to the design of high performance gas sensor, and the results are also beneficial to other fields such as energy conversion, environmental protection.

Oxygen-Induced Bi5+-Self-Doped Bi4V2O11 with a p–n Homojunction Toward Promoting the Photocatalytic Performance

Bi5+-self-doped Bi4V2O11 (Bi5+-BVO) nanotubes with p-n homojunctions are fabricated via an oxygen-induced strategy. Calcinating the as-spun fibers with abundant oxygen plays a pivotal role in achieving Bi5+ self-doping. Density functional theory calculations and experimental results indicate that Bi5+ self-doping can narrow the band gap of Bi4V2O11, which contributes to enhancing light harvesting. Moreover, Bi5+ self-doping endows Bi4V2O11 with n- and p-type semiconductor characteristics simultaneously, resulting in the construction of p-n homojunctions for retarding rapid electron-hole recombination. Benefiting from these favorable properties, Bi5+-BVO exhibits a superior photocatalytic performance in contrast to that of pristine Bi4V2O11. Furthermore, this is the first report describing the achievement of p-n homojunctions through self-doping, which gives full play to the advantages of self-doping.

Engineering 2D Nanofluidic Li-Ion Transport Channels for Superior Electrochemical Energy Storage

Rational surface engineering of 2D nanoarchitectures-based electrode materials is crucial as it may enable fast ion transport, abundant-surface-controlled energy storage, long-term structural integrity, and high-rate cycling performance. Here we developed the stacked ultrathin Co3 O4 nanosheets with surface functionalization (SUCNs-SF) converted from layered hydroxides with inheritance of included anion groups (OH- , NO3- , CO32- ). Such stacked structure establishes 2D nanofluidic channels offering extra lithium storage sites, accelerated Li-ion transport, and sufficient buffering space for volume change during electrochemical processes. Tested as an anode material, this unique nanoarchitecture delivers high specific capacity (1230 and 1011 mAh g-1 at 0.2 and 1 A g-1 , respectively), excellent rate performance, and long cycle capability (1500 cycles at 5 A g-1 ). The demonstrated advantageous features by constructing 2D nanochannels in nonlayered materials may open up possibilities for designing high-power lithium ion batteries.

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.

Template-free preparation of mesoporous single crystal In2O3 achieving superior ethanol gas sensing performance

Mesoporous single crystal indium oxide (In2O3) has been successfully prepared via a hydrothermal annealing route in the absence of templates and surfactants. An In2O3 mesoporous single crystal has larger surface areas and smaller pore diameter, and thus exhibits better ethanol gas sensing properties than mesoporous In2O3 with a large pore diameter which was prepared by adjusting the pH value.

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.

One-dimensional Bi2O3 QD-decorated BiVO4 nanofibers: electrospinning synthesis, phase separation mechanism and enhanced photocatalytic performance

In this work, we design and successfully fabricate novel Bi2O3 quantum dot (QD)-decorated BiVO4 nanofibers by a direct heat treatment of as-spun fibers. The Bi2O3 QDs with a size of 5–15 nm are well dispersed on the surface of the BiVO4 nanofibers with a diameter of 400–700 nm to form a Bi2O3 QD-decorated BiVO4 nanofiber photocatalyst. Based on the phase separation mechanism and the properties of solvents, a possible formation process of the Bi2O3 QD-decorated BiVO4 nanofibers has been proposed. The BiVO4 nanofibers decorated with Bi2O3 QDs exhibit much better photocatalytic performance than pure BiVO4 nanofibers. Photocurrent responses and electrochemical impedance spectra prove that decorating BiVO4 nanofibers with very small Bi2O3 QDs can effectively promote the separation of photoinduced carriers, which is beneficial for photocatalytic properties. More significantly, this work is relevant to environmental purification and photoelectrochemistry.

Engineering Mesoporous Single Crystals Co-Doped Fe2O3 for High-Performance Lithium Ion Batteries

To achieve high-efficiency lithium ion batteries (LIBs), an effective active electrode material is vital. For the first time, mesoporous single crystals cobalt-doped Fe2O3 (MSCs Co-Fe2O3) is synthesized using formamide as a pore forming agent, through a solvothermal process followed by calcination. Compared with mesoporous single crystals Fe2O3 (MSCs Fe2O3) and cobalt-doped Fe2O3 (Co-Fe2O3), MSCs Co-Fe2O3 exhibits a significantly improved electrochemical performance with high reversible capacity, excellent rate capability, and cycling life as anode materials for LIBs. The superior performance of MSCs Co-Fe2O3 can be ascribed to the combined structure characteristics, including Co-doping and mesoporous single-crystals structure, which endow Fe2O3 with rapid Li+ diffusion rate and tolerance for volume change.