Xueqin Liu

Facile synthesis of core-shell CuO/Ag nanowires with enhanced photocatalytic and enhancement in photocurrent.

CuO nanowires were grown on Cu foil via a simple cost-effective wet-chemical route in large scales and used as templates for making silver-coated CuO (CuO/Ag) core-shell nanowires. The coverage of Ag shells on CuO nanowires was controlled by varying the concentration of Ag precursor. The structure, composition, morphology and optical properties of the synthesized core-shell CuO/Ag nanowires (CACs) were considered. The discussion on the growth process of CACs revealed the important role of Sn(2+). And, the novel structure enlarged the range of absorbed light and enhanced the absorption intensity of light. The CACs were evaluated for their ability to degrade methyl orange (MeO) solution under visible-light irradiation. The rate of degradation of the as-prepared CACs was more than 7 times faster than that of using pure CuO nanowires under solar light irradiation. Moreover, the incorporation of Ag shells at the surface causes a quenching of PL emissions and enhanced photocurrent of CuO nanowires. The mechanisms of enhanced photocatalytic activity, luminescence emission quenching, and photocurrent multiplication of the core-shell nanowires have been discussed.

A facile way to fabricate graphene sheets on TiO2 nanotube arrays for dye-sensitized solar cell applications

Large-area graphene sheets on TiO2 nanotube arrays (RGO/TNAs) were fabricated using a simple electrochemical method. The RGO content loaded on the arrays was controlled by changing the electrochemical reaction time. The microstructures and properties of RGO/TNAs were characterized and measured using field emission scanning electron microscopy, X-ray diffraction pattern, X-ray photoelectron spectroscopy, FT-IR spectra, and ultraviolet–visible (UV–Vis) spectroscopy. The results indicated that an appropriate reaction time clearly enhances photoelectrochemical properties, while excessive RGO loading significantly lowers their performance. Remarkably, in sharp contrast to the dye-sensitized solar cells prepared by TNAs as photoanode, the RGO/TNAs showed a significantly enhanced power conversion efficiency of 4.46xa0%. The improvement of light harvesting is due to the excellent property of RGO and the special structure of the composite.

Carbon Quantum Dot Implanted Graphite Carbon Nitride Nanotubes: Excellent Charge Separation and Enhanced Photocatalytic Hydrogen Evolution

Graphite carbon nitride (g-C3 N4 ) is a promising candidate for photocatalytic hydrogen production, but only shows moderate activity owing to sluggish photocarrier transfer and insufficient light absorption. Herein, carbon quantum dots (CQDs) implanted in the surface plane of g-C3 N4 nanotubes were synthesized by thermal polymerization of freeze-dried urea and CQDs precursor. The CQD-implanted g-C3 N4 nanotubes (CCTs) could simultaneously facilitate photoelectron transport and suppress charge recombination through their specially coupled heterogeneous interface. The electronic structure and morphology were optimized in the CCTs, contributing to greater visible light absorption and a weakened barrier of the photocarrier transfer. As a result, the CCTs exhibited efficient photocatalytic performance under light irradiation with a high H2 production rate of 3538.3u2005μmolu2009g-1 u2009h-1 and a notable quantum yield of 10.94u2009% at 420u2005nm.

Ordered Single-Crystalline Anatase TiO2 Nanorod Clusters Planted on Graphene for Fast Charge Transfer in Photoelectrochemical Solar Cells

Achieving efficient charge transport is a great challenge in nanostructured TiO2 -electrode-based photoelectrochemical cells. Inspired by excellent directional charge transport and the well-known electroconductibility of 1D anatase TiO2 nanostructured materials and graphene, respectively, planting ordered, single-crystalline anatase TiO2 nanorod clusters on graphene sheets (rGO/ATRCs) via a facial one-pot solvothermal method is reported. The hierarchical rGO/ATRCs nanostructure can serve as an efficient light-harvesting electrode for dye-sensitized solar cells. In addition, the obtained high-crystallinity anatase TiO2 nanorods in rGO/ATRCs possess a lower density of trap states, thus facilitating diffusion-driven charge transport and suppressing electron recombination. Moreover, the novel architecture significantly enhances the trap-free charge diffusion coefficient, which contributes to superior electron mobility properties. By virtue of more efficient charge transport and higher energy conversion efficiency, the rGO/ATRCs developed in this work show significant advantages over conventional rGO-TiO2 nanoparticle counterparts in photoelectrochemical cells.

Fabrication of PEDOT films via a facile method and their application in Pt-free dye-sensitized solar cells

Poly(3,4-ethylenedioxythiophene) (PEDOT) has attracted much attention in the application of dye-sensitized solar cells (DSSCs) due to its outstanding photovoltaic property. PEDOT films were synthesized in a three-electrode system with a direct-current power supply to control the polymerization process, leading to a simplification of the electrochemical polymerization procedure. The morphology of PEDOT can be represented as a micro-sphere with three-dimensional network-like structures aggregated with plenty of nanoparticles. The polymerization voltage, polymerization time and the concentration of 3,4-ethylenedioxythiophene (EDOT) exhibited a significant influence on the photovoltaic characteristics of PEDOT films. Impressively, the DSSCs with optimum PEDOT films as counter electrodes (CEs) reached the highest power conversion efficiency (η) of 6.401%, which was comparable to that of a cell with platinum (Pt) CEs (6.493%). After modification by reduced graphene oxide (rGO), DSSCs equipped with PEDOT/rGO CEs reached an η of 7.115%, with an enhancement of 9.58% compared to that of Pt CEs. Thus, the rGO-coated network-like PEDOT can be considered as an economical alternative component to expensive Pt electrodes.

Influence of TiO2 Nanorod Arrays on the Bilayered Photoanode for Dye-Sensitized Solar Cells

A TiO2 bilayered structure consisting of TiO2 nanoparticles (TiO2NP) as an overlayer and single-crystal rutile TiO2 nanorods (TiO2 NRs) as an underlayer on a transparent conductive fluorine-doped tin oxide substrate was designed as the photoanode of dye-sensitized solar cells (DSSCs) through a facile hydrothermal treatment followed by a doctor-blade method. DSSCs based on the hierarchical TiO2 nano-architecture photoelectrode shows a power conversion efficiency of 7.39% because the relatively large specific surface area of TiO2NP increased thexa0dye absorption, and oriented one-dimensional TiO2 NRs enhanced the light harvesting capability, accelerating interfacial electron transport. In particular, we observed the growthxa0morphology of the TiO2 nanorod arrays in the bilayered photoanode and the influence of the whole solar cell. The result indicated that the TiO2 NRs layer clearly impacted the photoelectron chemical properties, while the vertical and intensive nanorod arrays significantly increased their performance.

Tailoring TiO2 nanotube‐interlaced graphite carbon nitride nanosheets for improving visible‐light‐driven photocatalytic performance

Abstract Rapid recombination of photoinduced electron–hole pairs is one of the major defects in graphitic carbon nitride (g‐C3N4)‐based photocatalysts. To address this issue, perforated ultralong TiO2 nanotube‐interlaced g‐C3N4 nanosheets (PGCN/TNTs) are prepared via a template‐based process by treating g‐C3N4 and TiO2 nanotubes polymerized hybrids in alkali solution. Shortened migration distance of charge transfer is achieved from perforated PGCN/TNTs on account of cutting redundant g‐C3N4 nanosheets, leading to subdued electron–hole recombination. When PGCN/TNTs are employed as photocatalysts for H2 generation, their in‐plane holes and high hydrophilicity accelerate cross‐plane diffusion to dramatically promote the photocatalytic reaction in kinetics and supply plentiful catalytic active centers. By having these unique features, PGCN/TNTs exhibit superb visible‐light H2‐generation activity of 1364 µmol h−1 g−1 (λ > 400 nm) and a notable quantum yield of 6.32% at 420 nm, which are much higher than that of bulk g‐C3N4 photocatalysts. This study demonstrates an ingenious design to weaken the electron recombination in g‐C3N4 for significantly enhancing its photocatalytic capability.