The exploration of photoanode materials with high efficiency and stability is the eternal pursuit for the realization of practically solar-driven photoelectrochemical (PEC) water splitting. Here we ...develop a deficient ternary metal sulfide (CdIn
S
) photoanode, and its PEC performance is significantly enhanced by introducing surface sulfur vacancies, achieving a photocurrent density of 5.73 mA cm
at 1.23 V vs. RHE and 1 Sun with an applied bias photon-to-current efficiency of 2.49% at 0.477 V vs. RHE. The experimental characterizations and theoretical calculations highlight the enhanced effect of surface sulfur vacancies on the interfacial charge separation and transfer kinetics, which also demonstrate the restrained surface states distribution and the transformation of active sites after introducing surface sulfur vacancies. This work may inspire more excellent work on developing sulfide-based photoanodes.
Solar-driven photothermal interfacial evaporation is considered as one of the most promising strategies in seawater desalination and wastewater treatment. In desalination, evaporation efficiency and ...salt resistance are regarded as two inter-constraint measures. Thus, it is still challenging to fabricate solar evaporators with both high evaporation efficiency and excellent salt resistance. In the present work, a self-floating Janus sponge composed of hydrophobic carbon black (CB) coating and hydrophilic porous thermoplastic polyurethane-carbon nanotube (TPC) nanofibrous substrate (TPC@CB) is fabricated via a simple electrospinning and gas templating expansion method. Attributing to the unique trilaminar functional architecture: the upper superhydrophobic solar-absorption coating, the intermediate ultrathin heat localization layer, and the lower cellular thermal insulation layer, the Janus TPC@CB sponge exhibits high evaporation efficiency (1.80 kg m–2 h–1 with an energy efficiency of 97.2% under 1.0 solar irradiation) and outstanding salt resistance ability. Moreover, zero liquid discharge in salt-containing wastewater treatment is realized using the Janus TPC@CB sponge as a solar-driven photothermal medium. This work provides a promising approach to seawater desalination and wastewater treatment.
Recent development on the synthesis and electrochemical properties of nanocages for high-performance supercapacitors is reviewed.
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•Nanocages are promising for electrode materials due ...to their unique nanoarchitectures.•The structural parameters illustrating the nanocage are discussed.•The synthesis methods of nanocages for SC applications are summarized.•The SC performance of nanocages and its relationship with the structure are presented.
Supercapacitor (SC) is one of the most promising and rapidly growing energy storage devices owing to its high power density, fast electrochemical processes and long service life. A great deal of effort has been devoted to the development of high-capacity and high-stability electrode materials. Among various structures, nanocages of hollow or frame-like structures with pores on the walls have unique advantages for SC materials because they provide a large number of active sites for electrochemical reactions and facilitate the ion transfer during electrochemical processes. This paper summarizes the latest advances in SC electrode materials with nanocage structures, including carbon materials, transition metal compounds, conducting polymers, etc., by emphasizing the synthetic strategies and structure-performance correlations, and aims to provide guidance for the future design and fabrication of optimized SC electrode materials.
Amorphous cobalt sulfide polyhedral nanocages are synthesized by utilizing zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as templates. Electrochemical characterization shows that CoS ...nanocages exhibit high specific capacitances, owing to their amorphous phase and novel structures.
Many previous reports have indicated that the applicable photochromism of WO 3 can only be achieved by combining with metals, semiconductors or organic polymers to improve the coloration efficiency ...and reversibility, while the investigation of intrinsic WO 3 photochromism has been severely prohibited by its small color change and slow coloration rate. Herein, we report hydrothermally prepared hydrated tungsten oxide nanosheets with fast and reversible intrinsic photochromic response. A gradual yellow-blue color change can be modulated with continuous UV illumination. The following UV/ozone treatment can bleach the nanosheets back to their initial yellowish color within minutes and the reversible process can be continued 20 times without noticeable attenuation, which has never been reported for intrinsic WO 3 photo response. The thin-layered nanostructure of WO 3 indicates a short ionic diffusion length for surface attached species, which promotes fast surface water decomposition upon UV irradiation and accelerates proton intercalation/deintercalation, thus speeding up both the coloration and the bleaching processes. Our research elucidates that hydrated nanostructured WO 3 can present significantly improved photochromic response even without WO 3 /metal, WO 3 /semiconductor or WO 3 /polymer combination, which may lead to technological advances with simple, facilely prepared WO 3 nanosheets in areas such as photolithography, rewritable optical memory devices and nanoinks in inkjet printing.
Truncated rhombic dodecahedral zeolitic imidazolate framework-8 (ZIF-8) nanocrystals are fabricated with acetate as a modulating ligand; ZnS hollow polyhedra with uniform morphology are obtained ...using the ZIF-8 templates.
Bismuth vanadate (BiVO4) nanosheets have been hydrothermally synthesized in the presence of sodium dodecyl benzene sulfonate (SDBS) as a morphology-directing template. The nanosheets were ...characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) equipped with an X-ray energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), IR spectroscopy, transmission electron microscopy (TEM), and high-resolution TEM (HR-TEM). The BiVO4 nanosheets had a monoclinic structure, were ca. 10−40 nm thick, and showed a preferred (010) surface orientation. The formation mechanism and the effects of reaction temperature and time on the products were investigated. UV−visible diffuse reflection spectra indicated that the BiVO4 nanosheets had outstanding spectral selectivity and improved color properties compared with the corresponding bulk materials. Furthermore, the nanosheets showed good visible photocatalytic activities as determined by degradation of N,N,N‘,N‘-tetraethylated rhodamine (RB) under solar irradiation.
Mesoporous alumina fibers were successfully synthesized viaan electrospinning technique combined with a sol-gel method in the presence of a triblock copolymer as a structure directing agent. The ...amorphous alumina fibers derived from the electrospun xerogel fibers after calcinations at 450 degree C and the gamma -Al sub(2)O sub(3) fibers obtained after the xerogel fibers were calcined at 700 degree C exhibit uniform mesopores with fiber diameters of 130-200 nm, and BET surface areas up to 264.1 m super(2) g super(-1) and 242.6 m super(2) g super(-1), respectively. After the xerogel fibers were calcined at 1100 degree C, with the transformation from gamma -Al sub(2)O sub(3) to alpha -Al sub(2)O sub(3), a significant grain growth occurs and the mesopores disappear. Further investigation indicates that the gamma -Al sub(2)O sub(3) fibers have good adsorption properties toward Congo red with a maximum adsorption capacity of 781.25 mg g super(-1) for the sample obtained at 700 degree C. In addition, the fibers show a good stability in acidic conditions and during a reuse process, which indicates their potential applications in adsorption as well as related areas, such as catalysis and catalyst supports.
Impurity states in semiconductors are so important for optical related properties that understanding the role of native and imported defects is essential to design highly active semiconductors. Here, ...the structural and electronic properties of ZnGa2O4 with native atomic substitution, oxygen vacancies, and imported N doping are first investigated by first-principles calculations. It is demonstrated that native atomic substitution is energetically unfavorable and the most stable existence forms for N doping and O vacancies are N1– and O2+ states in most cases under various chemical environments. The band structures and density of states reveal that the photochemical property is significantly enhanced only by 2Ns doping with a great increase of valence band maximum relative to the Fermi level, whereas single-N atom doping or import of O vacancies or simultaneous import of N doping and O vacancies just generates impurity states in the band gaps. Moreover, experimental characterizations including X-ray photoelectron spectroscopy and diffuse reflectance spectroscopy spectra confirm the above theoretical results, and optical calculations further illustrate the effects of defects for light absorption. Our results will be helpful to understand the effects of native point defects and external nitrogen doping on spinel ZnGa2O4 and design its band gap with desired optical properties.
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