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Moniz S.J.A.,University College London | Zhu J.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Tang J.,University College London
Advanced Energy Materials | Year: 2014

The most important factors dominating solar hydrogen synthesis efficiency include light absorption, charge separation and transport, and surface chemical reactions (charge utilization). In order to tackle these factors, an ordered 1D junction cascade photoelectrode for water splitting, grown via a simple low-cost solution-based process and consisting of nanoparticulate BiVO4 on 1D ZnO rods with cobalt phosphate (Co-Pi) on the surface is synthesized. Flat-band measurements reveal the feasibility of charge transfer from BiVO4 to ZnO, supported by PL measurements and photocurrent observation in the presence of an efficient hole scavenger, which demonstrate that quenching of luminescence of BiVO4 and enhanced current are caused by electron transfer from BiVO4 to ZnO. A dramatic cathodic shift in onset potential under both visible and full arc irradiation, coupled with a 12-fold increase in photocurrent (ca. 3 mA cm-2) are observed compared to BiVO 4, resulting in ≈47% IPCE at 410 nm (4% for BiVO4) with high solar energy conversion efficiency (0.88%). The reasons for these enhancements stem from enhanced light absorption and trapping, in situ rectifying electron transfer from BiVO4 to ZnO, hole transfer to Co-Pi for water oxidation, and facilitating electron transport along 1D ZnO. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Wang Q.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Wang X.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Wang X.,Soochow University of China | Chai Z.,Soochow University of China | Hu W.,CAS Beijing National Laboratory for Molecular
Chemical Society Reviews | Year: 2013

Carbon nanotubes (CNTs) and graphene, and materials based on these, are largely used in multidisciplinary fields. Many techniques have been put forward to synthesize them. Among all kinds of approaches, the low-temperature plasma approach is widely used due to its numerous advantages, such as highly distributed active species, reduced energy requirements, enhanced catalyst activation, shortened operation time and decreased environmental pollution. This tutorial review focuses on the recent development of plasma synthesis of CNTs and graphene based materials and their electrochemical application in fuel cells. This journal is © The Royal Society of Chemistry. Source


Zhao G.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Wen T.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Chen C.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Wang X.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells
RSC Advances | Year: 2012

As a fascinating two-dimensional carbon allotrope, graphene has triggered a 'gold rush' all over scientific research areas especially since the Nobel Prize for Physics in 2010. To exploit the prominent properties of graphene-based nanomaterials, two important problems are focused in this review: one is the synthesis of these graphene-based nanomaterials with different kinds of well-defined structures, and the other is the effective application of them as active nanomaterials in functional devices or processes. In this critical review, from the viewpoint of chemistry and materials, we give a brief overview of the recent significant advances in the synthesis of graphene-based nanomaterials and their applications in energy-related areas and environmental pollution remediation areas, including supercapacitors, lithium ion batteries, solar cells, adsorption, and degradation of organic/inorganic pollutants from large volumes of aqueous solutions in environmental pollution cleanup. The main challenges and perspectives of the materials for future research are also discussed. © The Royal Society of Chemistry. 2012. Source


Ding C.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Cheng W.,Sichuan University | Sun Y.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Wang X.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells
Dalton Transactions | Year: 2014

The chemical affinity of graphene oxide (GO) nanosheets with radionuclides (Eu(iii) and U(vi)) was determined by macroscopic, spectroscopic and modeling techniques. The macroscopic results showed that the adsorption of Eu(iii) and U(vi) on GO nanosheets was independent of ionic strength, indicating that inner-sphere surface complexation predominated their adsorption. The maximum adsorption capacities calculated from a Langmuir model at pH 4.0 and T = 303 K were 208.33 mg U(vi) and 28.70 mg Eu(iii) per gram of GO nanosheets, respectively. No hysteresis was observed for both Eu(iii) and U(vi) on GO nanosheets when desorption was initiated by lowering solution pH. While desorption was induced by replacing the radionuclide supernatant liquid with radionuclide-free electrolyte solution, the adsorption-desorption hysteresis was observed for U(vi) but not for Eu(iii), indicating that the chemical affinity of GO nanosheets with U(vi) was stronger than that of GO nanosheets with Eu(iii). The adsorption behaviors of Eu(iii) and U(vi) on GO nanosheets can be fitted by a double diffuse layer surface complexation model with the mononuclear monodentate >SOM(n-1)+ and >SOMOH(n-2)+ complexes, and larger log K values of U(vi) was observed as compared to those of Eu(iii). According to the spectroscopic analysis, the irreversible adsorption of U(vi) on GO nanosheets at variable radionuclide concentrations was attributed to the oxygen-containing functional groups. © 2014 The Royal Society of Chemistry. Source


Ren X.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Li J.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Tan X.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells | Wang X.,CAS Hefei Key Laboratory of Novel Thin Film Solar Cells
Dalton Transactions | Year: 2013

This paper presents a comparative study of Cu(ii) decontamination by three different carbonaceous materials, i.e., graphene oxide, multiwalled carbon nanotubes, and activated carbon. The three carbonaceous materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, N2-BET surface area analysis, and potentiometric acid-base titrations in detail. Also, Cu(ii) adsorption on the three types of carbonaceous materials as a function of pH and Cu(ii) ion concentration were investigated. The constant capacitance model was used to determine the appropriate surface reactions of Cu(ii) adsorption on carbonaceous materials with the aid of FITEQL 4.0 software. In addition, how the surface area and the total concentration of acidic functional groups influencing the adsorption capacities of the three carbonaceous materials for Cu(ii) removal were elucidated. The results have an important role in predicting the adsorption capacity of surface modified carbonaceous materials. © 2013 The Royal Society of Chemistry. Source

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