Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Tao An is active.

Publication


Featured researches published by Tao An.


RSC Advances | 2015

Co3O4 nanoparticles grown on N-doped Vulcan carbon as a scalable bifunctional electrocatalyst for rechargeable zinc–air batteries

Tao An; Xiaoming Ge; T. S. Andy Hor; F. W. Thomas Goh; Dongsheng Geng; Guojun Du; Yi Zhan; Zhaolin Liu; Yun Zong

Bifunctional electrocatalysts for rechargeable metal–air batteries often encounter catalyst leaching-resultant performance degradation upon cycling of the batteries, which requires an improvement in stability of the catalyst nanoparticles via immobilization onto conductive supports. Herein, we report in situ growth of Co3O4 nanoparticles onto concurrently synthesized N-doped Vulcan carbon (NVC) to produce Co3O4/NVC powders with tuneable loading density as scalable, stable and efficient hybrid bifunctional electrocatalysts. With an optimized composition the hybrid catalyst exhibited satisfactory ORR and OER activity, giving a voltage difference as small as 0.10 V between the onset potential and half-wave potential at discharge. The good performance of the rechargeable zinc–air batteries constructed using Co3O4/NVC as air-cathodes suggests such a hybrid bifunctional electrocatalyst is a practical and cost-effective solution for applications which demand a large quantity of materials, e.g. in grid-scale energy storage and electric vehicles.


Journal of the American Chemical Society | 2011

Five-Dimensional Incommensurate Structure of the Melilite Electrolyte [CaNd]2[Ga]2[Ga2O7]2

Fengxia Wei; Tom Baikie; Tao An; Martin Schreyer; Christian Kloc; Timothy J. White

Melilite-type gallium oxides are potential intermediate temperature electrolytes for solid oxide fuel cells. Single crystals of [CaNd](2)[Ga](2)[Ga(2)O(7)](2) grown using an optical floating zone furnace have been investigated using transmission electron microscopy and powder and single-crystal X-ray diffraction. The anion array topologically conforms to a [(3.5.4.5)(2), 3.5.3.5] network that contains distorted pentagonal tunnels. The distortion is necessary to achieve space filling and accommodate structural misfit between the layers. Satisfactory bond lengths and angles are obtained through two-dimensional modulation in the tetragonal based plane, leading to five-dimensional symmetry in the superspace group P(4⁻)2(1)m(α,α,0)00s((a⁻)a,0)000, α = 0.2319(2), with modulation vectors q(1) = α(a* + b*) and q(2) = α(-a* + b*). Both displacive and occupational modulations are found. Through this mechanism, melilites are primed to accommodate mobile oxygen interstitials, suggesting a rational approach to crystallochemical tailoring that will enhance ionic diffusion and optimize electrolyte performance.


Inorganic Chemistry | 2012

Crystal Chemistry of Melilite [CaLa](2)[Ga](2)[Ga2O7](2): a Five Dimensional Solid Electrolyte

Fengxia Wei; Tom Baikie; Tao An; Christian Kloc; Jun Wei; Timothy John White

Melilite-type [A(2)](2)[B(I)](2)[B(II)(2)O(7)](2) gallates are promising ion conducting electrolytes for deployment in solid oxide fuel cells. Single crystals of [CaLa](2)[Ga](2)[Ga(2)O(7)](2), grown in an optical floating zone furnace, were investigated using a combination of transmission electron microscopy and single crystal X-ray diffraction. Strong anisotropic displacements of oxygen arise from the structural misfit between the interlayer Ca/La cations and the [Ga]-[Ga(2)O(7)] tetrahedral layers. A model employing two-dimensional modulation achieves bond lengths and bond angles that preserve satisfactory bond valence sums throughout the structure. The melilite belongs to the tetragonal superspace group P42(1)m(α, α, 0)00s(α, α, 0)000, α = 0.2160(5), with a subcell metric of a = 7.9383(2) Å, c = 5.2641(3) Å, onto which modulation vectors are superimposed: q(1) = α (a* + b*), q(2) = α (-a* + b*). Both displacive (cation and anion) and occupational (cation) modulations contribute to incommensuration. The analysis of structural adjustments that accompany changes in temperature and composition provides assurance that the crystal chemical model is correct. By better understanding the flexibility of this modulated structure a rational approach toward crystallochemical optimization of electrolyte performance by enhancing oxygen mobility becomes feasible.


Inorganic Chemistry | 2014

Hydrothermal synthesis, structure investigation, and oxide ion conductivity of mixed Si/Ge-based apatite-type phases

Henan Li; Tom Baikie; Stevin S. Pramana; J F Shin; Philip J. Keenan; Peter R Slater; Frank Brink; James R. Hester; Tao An; Timothy John White

Apatite-type oxides ([A(I)4][A(II)6][(BO4)6]O2), particularly those of the rare-earth silicate and germanate systems, are among the more promising materials being considered as alternative solid oxide fuel cell electrolytes. Nonstoichiometric lanthanum silicate and germanate apatites display pure ionic conductivities exceeding those of yttria-stabilized zirconia at moderate temperatures (500-700 °C). In this study, mixed Si/Ge-based apatites were prepared by hydrothermal synthesis under mild conditions rather than the conventional solid-state method at high temperatures. Single-phase and highly crystalline nanosized apatite powders were obtained with the morphology changing across the series from spheres for the Si-based end member to hexagonal rods for the Ge-based end member. Powder X-ray and neutron analysis found all of these apatites to be hexagonal (P63/m). Quantitative X-ray microanalysis established the partial (<15 at%) substitution of La(3+) by Na(+) (introduced from the NaOH hydrothermal reagent), which showed a slight preference to enter the A(I) 4f framework position over the A(II) 6h tunnel site. Moreover, retention of hydroxide (OH(-)) was confirmed by IR spectroscopy and thermogravimetric analysis, and these apatites are best described as oxyhydroxyapatites. To prepare dense pellets for conductivity measurements, both conventional heat treatment and spark plasma sintering methods were compared, with the peculiar features of hydrothermally synthesized apatites and the influence of sodium on the ionic conductivity considered.


Journal of the American Chemical Society | 2016

Interstitial Oxide Ion Distribution and Transport Mechanism in Aluminum-Doped Neodymium Silicate Apatite Electrolytes

Tao An; Tom Baikie; Alodia Orera; Ross O. Piltz; Martin Meven; Peter R. Slater; Jun Wei; M. L. Sanjuán; Timothy John White

Rare earth silicate apatites are one-dimensional channel structures that show potential as electrolytes for solid oxide fuel cells (SOFC) due to their high ionic conductivity at intermediate temperatures (500-700 °C). This advantageous property can be attributed to the presence of both interstitial oxygen and cation vacancies, that create diffusion paths which computational studies suggest are less tortuous and have lower activation energies for migration than in stoichiometric compounds. In this work, neutron diffraction of Nd(28+x)/3AlxSi6-xO26 (0 ≤ x ≤ 1.5) single crystals identified the locations of oxygen interstitials, and allowed the deduction of a dual-path conduction mechanism that is a natural extension of the single-path sinusoidal channel trajectory arrived at through computation. This discovery provides the most thorough understanding of the O(2-) transport mechanism along the channels to date, clarifies the mode of interchannel motion, and presents a complete picture of O(2-) percolation through apatite. Previously reported crystallographic and conductivity measurements are re-examined in the light of these new findings.


Inorganic Chemistry | 2014

Structural study of the apatite Nd8Sr2Si6O26 by Laue neutron diffraction and single-crystal raman spectroscopy

Tao An; Alodia Orera; Tom Baikie; Jason S Herrin; Ross O. Piltz; Peter R. Slater; Timothy John White; M. L. Sanjuán

A single-crystal structure determination of Nd8Sr2Si6O26 apatite, a prototype intermediate-temperature electrolyte for solid oxide fuel cells grown by the floating-zone method, was completed using the combination of Laue neutron diffraction and Raman spectroscopy. While neutron diffraction was in good agreement with P6₃/m symmetry, the possibility of P6₃ could not be convincingly excluded. This ambiguity was removed by the collection of orientation-dependent Raman spectra that could only be consistent with P6₃/m. The composition of Nd8Sr2Si6O26 was independently verified by powder X-ray diffraction in combination with electron probe microanalysis, with the latter confirming a homogeneous distribution of Sr and the absence of chemical zonation commonly observed in apatites. This comprehensive crystallochemical description of Nd8Sr2Si6O26 provides a baseline to quantify the efficacy of cation vacancies, oxygen superstoichiometry, and symmetry modification for promoting oxygen-ion mobility.


ACS Applied Materials & Interfaces | 2018

One-Step Facile Synthesis of Cobalt Phosphides for Hydrogen Evolution Reaction Catalysts in Acidic and Alkaline Medium

Afriyanti Sumboja; Tao An; Hai Yang Goh; Mechthild Lübke; Dougal P. Howard; Yijie Xu; Albertus D. Handoko; Yun Zong; Zhaolin Liu

Catalysts for hydrogen evolution reaction are in demand to realize the efficient conversion of hydrogen via water electrolysis. In this work, cobalt phosphides were prepared using a one-step, scalable, and direct gas-solid phosphidation of commercially available cobalt salts. It was found that the effectiveness of the phosphidation reaction was closely related to the state of cobalt precursors at the reaction temperature. For instance, a high yield of cobalt phosphides obtained from the phosphidation of cobalt(II) acetate was related to the good stability of cobalt salt at the phosphidation temperature. On the other hand, easily oxidizable salts (e.g., cobalt(II) acetylacetonate) tended to produce a low amount of cobalt phosphides and a large content of metallic cobalt. The as-synthesized cobalt phosphides were in nanostructures with large catalytic surface areas. The catalyst prepared from phosphidation of cobalt(II) acetate exhibited an improved catalytic activity as compared to its counterpart derived from phosphidation of cobalt(II) acetylacetonate, showing an overpotential of 160 and 175 mV in acidic and alkaline electrolytes, respectively. Both catalysts also displayed an enhanced long-term stability, especially in the alkaline electrolyte. This study illustrates the direct phosphidation behavior of cobalt salts, which serve as a good vantage point in realizing the large-scale synthesis of transition-metal phosphides for high-performance electrocatalysts.


Journal of Molecular and Engineering Materials | 2015

Nanostructured Perovskite LaCo1-xMnxO3 as Bifunctional Catalysts for Rechargeable Metal-Air Batteries

Xiaoming Ge; Bing Li; Delvin Wuu; Afriyanti Sumboja; Tao An; T. S. Andy Hor; Yun Zong; Zhaolin Liu

Bifunctional catalyst that is active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most important components of rechargeable metal–air batteries. Nanostructured perovskite bifunctional catalysts comprising La, Co and Mn(LaCo1-xMnxO3, LCMO) are synthesized by hydrothermal methods. The morphology, structure and electrochemical activity of the perovskite bifunctional catalysts are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) techniques. Nanorod, nanodisc and nanoparticle are typical morphologies of LCMO. The electrocatalytic activity of LCMO is significantly improved by the addition of conductive materials such as carbon nanotube. To demonstrate the practical utilization, LCMO in the composition of LaCo0.8Mn0.2O3(LCMO82) is used as air cathode catalysts for rechargeable zinc–air batteries. The battery prototype can sustain 470 h or 40 discharge–charge cycles equivalent.


ACS Catalysis | 2015

Oxygen Reduction in Alkaline Media: From Mechanisms to Recent Advances of Catalysts

Xiaoming Ge; Afriyanti Sumboja; Delvin Wuu; Tao An; Bing Li; F. W. Thomas Goh; T. S. Andy Hor; Yun Zong; Zhaolin Liu


Advanced Energy Materials | 2015

Tellurium@Ordered Macroporous Carbon Composite and Free-Standing Tellurium Nanowire Mat as Cathode Materials for Rechargeable Lithium-Tellurium Batteries

Ning Ding; Shao Feng Chen; Dong Sheng Geng; Sheau Wei Chien; Tao An; T. S. Andy Hor; Zhaolin Liu; Shu-Hong Yu; Yun Zong

Collaboration


Dive into the Tao An's collaboration.

Top Co-Authors

Avatar

Tom Baikie

Nanyang Technological University

View shared research outputs
Top Co-Authors

Avatar

Timothy John White

Nanyang Technological University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Christian Kloc

Nanyang Technological University

View shared research outputs
Top Co-Authors

Avatar

Jun Wei

Nanyang Technological University

View shared research outputs
Top Co-Authors

Avatar

Fengxia Wei

University of Cambridge

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge