The photo-electro-chemical （PEC） splitting of water requires semiconductor materials with a minimum energy gap of 1.23 eV along with conduction and valence bands overlapping the oxidation of H20 and reduction of H＋...The photo-electro-chemical （PEC） splitting of water requires semiconductor materials with a minimum energy gap of 1.23 eV along with conduction and valence bands overlapping the oxidation of H20 and reduction of H＋ respectively. This work overcomes the limitations of stoichiometric titania by manufacturing fine scale fibres that exhibit a compositional gradient of oxygen vacancies across the fibre length. In such a fibre configuration the fibre end that is chemically reduced to a relatively small extent performs as the photoanode and the oxygen vacan- cies enhance the absorption of light. The fibre end that is reduced the most consists of Magn61i phases and exhibits metallic electrical conductivity that enhances the electron-hole separation. The structure and composition of the functionally graded fibres, which were manufactured through extrusion, pressureless sintering and carbo-thermal reduction, are studied using XRD and electron microscopy. Electrochemical impedance spectroscopy measure- ments were performed in a three-electrode electrochemical system and showed that the oxygen vacancies in the functionally graded fibres affect the fiat band potential and have increased carrier density. The efficiency of the system was evaluated with PEC measurements that shows higher efficiency for the functionally graded fibres com- pared to homogeneous TiO2 or Magn61i phase fibres. The functionally graded and fine scale fibres have the potential to be used as an array of active fibres for water splitting applications.展开更多
This paper examines the selection and performance evaluation of a variety of piezoelectric materials for cantilever-based sensor applications.The finite element analysis method is implemented to evaluate the relative ...This paper examines the selection and performance evaluation of a variety of piezoelectric materials for cantilever-based sensor applications.The finite element analysis method is implemented to evaluate the relative importance of materials properties such as Young's Modulus(E),piezoelectric stress constants(e_(31)),dielectric constant(ε)and Poisson's ratio(ν)for cantilever-based sensor applications.An analytic hierarchy process(AHP)is used to assign weights to the properties that are studied for the sensor structure under study.A technique for order preference by similarity to ideal solution(TOPSIS)is used to rank the performance of the piezoelectric materials in the context of sensor voltage outputs.The ranking achieved by the TOPSIS analysis is in good agreement with the results obtained from finite element method simulation.The numerical simulations show that K_(0.5)Na_(0.5)NbO_(3)-LiSbO_(3)(KNN-LS)materials family is important for sensor application.Young's modulus(E)is most influencing material's property followed by piezoelectric constant(e_(31)),dielectric constant(ε)and Poisson's ratio(ν)for cantilever-based piezoelectric sensor applications.展开更多
基金the European Union’s Seventh Framework Programme(FP7/2007-2013)/ERC Grant Agreement no.320963 on Novel Energy Materials,Engineering,Science and Integrated Systems(NEMESIS)supported by The European Union under FP7 Project309846,"Photocatalytic Materials for the Destruction of Recalcitrant Organic Industrial Waste–PCATDES"
文摘The photo-electro-chemical （PEC） splitting of water requires semiconductor materials with a minimum energy gap of 1.23 eV along with conduction and valence bands overlapping the oxidation of H20 and reduction of H＋ respectively. This work overcomes the limitations of stoichiometric titania by manufacturing fine scale fibres that exhibit a compositional gradient of oxygen vacancies across the fibre length. In such a fibre configuration the fibre end that is chemically reduced to a relatively small extent performs as the photoanode and the oxygen vacan- cies enhance the absorption of light. The fibre end that is reduced the most consists of Magn61i phases and exhibits metallic electrical conductivity that enhances the electron-hole separation. The structure and composition of the functionally graded fibres, which were manufactured through extrusion, pressureless sintering and carbo-thermal reduction, are studied using XRD and electron microscopy. Electrochemical impedance spectroscopy measure- ments were performed in a three-electrode electrochemical system and showed that the oxygen vacancies in the functionally graded fibres affect the fiat band potential and have increased carrier density. The efficiency of the system was evaluated with PEC measurements that shows higher efficiency for the functionally graded fibres com- pared to homogeneous TiO2 or Magn61i phase fibres. The functionally graded and fine scale fibres have the potential to be used as an array of active fibres for water splitting applications.
文摘This paper examines the selection and performance evaluation of a variety of piezoelectric materials for cantilever-based sensor applications.The finite element analysis method is implemented to evaluate the relative importance of materials properties such as Young's Modulus(E),piezoelectric stress constants(e_(31)),dielectric constant(ε)and Poisson's ratio(ν)for cantilever-based sensor applications.An analytic hierarchy process(AHP)is used to assign weights to the properties that are studied for the sensor structure under study.A technique for order preference by similarity to ideal solution(TOPSIS)is used to rank the performance of the piezoelectric materials in the context of sensor voltage outputs.The ranking achieved by the TOPSIS analysis is in good agreement with the results obtained from finite element method simulation.The numerical simulations show that K_(0.5)Na_(0.5)NbO_(3)-LiSbO_(3)(KNN-LS)materials family is important for sensor application.Young's modulus(E)is most influencing material's property followed by piezoelectric constant(e_(31)),dielectric constant(ε)and Poisson's ratio(ν)for cantilever-based piezoelectric sensor applications.
