scispace - formally typeset
Search or ask a question
Author

Pan Xiong

Bio: Pan Xiong is an academic researcher from University of Technology, Sydney. The author has contributed to research in topics: Graphene & Oxide. The author has an hindex of 29, co-authored 47 publications receiving 2862 citations. Previous affiliations of Pan Xiong include Nanjing University of Science and Technology & University of Texas at Austin.


Papers
More filters
Journal ArticleDOI
TL;DR: It is found that these holey oxide nanosheets exhibit strong mechanical stability inherited from graphene oxide, displaying minimal structural changes during lithiation/delithiation processes, and could open up opportunities in many energy storage and conversion systems.
Abstract: Transition metal oxide nanomaterials are promising electrodes for alkali-ion batteries owing to their distinct reaction mechanism, abundant active sites and shortened ion diffusion distance. However, detailed conversion reaction processes in terms of the oxidation state evolution and chemical/mechanical stability of the electrodes are still poorly understood. Herein we explore a general synthetic strategy for versatile synthesis of various holey transition metal oxide nanosheets with adjustable hole sizes that enable greatly enhanced alkali-ion storage properties. We employ in-situ transmission electron microscopy and operando X-ray absorption structures to study the mechanical properties, morphology evolution and oxidation state changes during electrochemical processes. We find that these holey oxide nanosheets exhibit strong mechanical stability inherited from graphene oxide, displaying minimal structural changes during lithiation/delithiation processes. These holey oxide nanosheets represent a promising material platform for in-situ probing the electrochemical processes, and could open up opportunities in many energy storage and conversion systems.

329 citations

Journal ArticleDOI
TL;DR: A ternary cobalt ferrite/graphene/polyaniline nanocomposite (CGP) was designed and fabricated via a facile two-step approach as discussed by the authors.

224 citations

Journal ArticleDOI
TL;DR: In this article, a cobalt ferrite-polyaniline photocatalyst is successfully prepared by in situ oxidative polymerization, and a significant adsorption can be observed in the case of the anionic dyes and neutral dyes because the negatively charged groups or the electron-rich groups of these dyes undergo chemical interactions with the positively charged backbone of PANI.
Abstract: A cobalt ferrite–polyaniline photocatalyst is successfully prepared by in situ oxidative polymerization. The excellent magnetic properties of CoFe2O4 are maintained in the composite to some extent, and therefore the photocatalyst can be separated easily by an external magnetic field. A significant adsorption can be observed in the case of the anionic dyes and neutral dyes because the negatively charged groups or the electron-rich groups of these dyes undergo chemical interactions with the positively charged backbone of polyaniline (PANI). Such an adsorption helps in promoting the photodegradation of the dyes. It is interesting that although CoFe2O4 alone is an inactive visible-light-driven photocatalyst, the combination of CoFe2O4 nanoparticles with PANI leads to high photocatalytic activity for the degradation of the dyes under visible light irradiation. The dramatic enhancement in photoactivity can be attributed to the excited state electrons in PANI which can migrate to the conduction band (CB) of CoFe2O4, and the photogenerated holes in the valence band (VB) of CoFe2O4 which can directly transfer to the HOMO of PANI, effectively preventing a direct recombination of electrons and holes. Due to electrostatic repulsion, the cationic dyes containing positively charged groups cannot easily gain access to the positively charged backbone of PANI, giving very low photodegradation rates.

181 citations

Journal ArticleDOI
TL;DR: The interface modulation of superlattices providing a promising approach for designing advanced electrocatalysts is heralded, with high activity and stability toward the overall water splitting on the MoS2/NiFe-LDHsuperlattice bifunctional electrocatalyst, outperforming the commercial Pt/C-RuO2 couple.
Abstract: Molecular-scale modulation of interfaces between different unilamellar nanosheets in superlattices is promising for efficient catalytic activities. Here, three kinds of superlattices from alternate restacking of any two of the three unilamellar nanosheets of MoS2, NiFe-layered double hydroxide (NiFe-LDH), and graphene are systematically investigated for electrocatalytic water splitting. The MoS2/NiFe-LDH superlattice exhibits a low overpotential of 210 and 110 mV at 10 mA cm-2 for oxygen evolution reaction (OER) and alkaline hydrogen evolution reaction (HER), respectively, superior than MoS2/graphene and NiFe-LDH/graphene superlattices. High activity and stability toward the overall water splitting are also demonstrated on the MoS2/NiFe-LDH superlattice bifunctional electrocatalyst, outperforming the commercial Pt/C-RuO2 couple. This outstanding performance can be attributed to optimal adsorption energies of both HER and OER intermediates on the MoS2/NiFe-LDH superlattice, which originates from a strong electronic coupling effect at the heterointerfaces. These results herald the interface modulation of superlattices providing a promising approach for designing advanced electrocatalysts.

177 citations

Journal ArticleDOI
TL;DR: In this article, a simple and straightforward strategy was developed to fabricate magnetically separable MnFe2O4-graphene photocatalysts with differing graphene content.
Abstract: A simple and straightforward strategy was developed to fabricate magnetically separable MnFe2O4–graphene photocatalysts with differing graphene content. It was found that graphene sheets were fully exfoliated and decorated with MnFe2O4 nanocrystals having an average diameter of 5.65 nm and a narrow particle size distribution. It is very interesting that, although MnFe2O4 alone is photocatalytically inactive under visible light irradiation, the combination of MnFe2O4 nanoparticles with graphene sheets leads to high photocatalytic activity for the degradation of methylene blue under visible light irradiation. The strong magnetic property of MnFe2O4 nanoparticles can be used for magnetic separation in a suspension system, and therefore it does not require additional magnetic components as is the usual case. Consequently, the MnFe2O4–graphene system becomes a dual function photocatalyst. The significant enhancement in photoactivity under visible light irradiation can be ascribed to the reduction of graphene o...

173 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: The unique advances on ultrathin 2D nanomaterials are introduced, followed by the description of their composition and crystal structures, and the assortments of their synthetic methods are summarized.
Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

3,628 citations

Posted Content
TL;DR: The two-step solution-phase reactions to form hybrid materials of Mn(3)O(4) nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications should offer a new technique for the design and synthesis of battery electrodes based on highly insulating materials.
Abstract: We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

1,587 citations

Journal ArticleDOI
TL;DR: The state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors is summarized and key technical challenges are highlighted regarding further research in this thriving field.
Abstract: Notably, many significant breakthroughs for a new generation of supercapacitors have been reported in recent years, related to theoretical understanding, material synthesis and device designs. Herein, we summarize the state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors. Firstly, fundamental understanding of the mechanism is mainly focused on the relationship between the structural properties of electrode materials and their electrochemical performances based on some in situ characterization techniques and simulations. Secondly, some emerging electrode materials are discussed, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), MXenes, metal nitrides, black phosphorus, LaMnO3, and RbAg4I5/graphite. Thirdly, the device innovations for the next generation of supercapacitors are provided successively, mainly emphasizing flow supercapacitors, alternating current (AC) line-filtering supercapacitors, redox electrolyte enhanced supercapacitors, metal ion hybrid supercapacitors, micro-supercapacitors (fiber, plane and three-dimensional) and multifunctional supercapacitors including electrochromic supercapacitors, self-healing supercapacitors, piezoelectric supercapacitors, shape-memory supercapacitors, thermal self-protective supercapacitors, thermal self-charging supercapacitors, and photo self-charging supercapacitors. Finally, the future developments and key technical challenges are highlighted regarding further research in this thriving field.

1,397 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the application of metal-organic frameworks (MOFs) in photocatalytic degradation of organic pollutants is presented, where the reported examples are collected and analyzed; and the reaction mechanism, the influence of various factors on the catalytic performance, involved challenges, and the prospect are discussed and estimated.
Abstract: Efficient removal of organic pollutants from wastewater has become a hot research topic due to its ecological and environmental importance. Traditional water treatment methods such as adsorption, coagulation, and membrane separation suffer from high operating costs, and even generate secondary pollutants. Photocatalysis on semiconductor catalysts (TiO2, ZnO, Fe2O3, CdS, GaP, and ZnS) has demonstrated efficiency in degrading a wide range of organic pollutants into biodegradable or less toxic organic compounds, as well as inorganic CO2, H2O, NO3−, PO43−, and halide ions. However, the difficult post-separation, easy agglomeration, and low solar energy conversion efficiency of these inorganic catalysts limit their large scale applications. Exploitation of new catalysts has been attracting great attention in the related research communities. In the past two decades, a class of newly-developed inorganic–organic hybrid porous materials, namely metal–organic frameworks (MOFs) has generated rapid development due to their versatile applications such as in catalysis and separation. Recent research has showed that these materials, acting as catalysts, are quite effective in the photocatalytic degradation of organic pollutants. This review highlights research progress in the application of MOFs in this area. The reported examples are collected and analyzed; and the reaction mechanism, the influence of various factors on the catalytic performance, the involved challenges, and the prospect are discussed and estimated. It is clear that MOFs have a bright future in photocatalysis for pollutant degradation.

1,338 citations

Journal ArticleDOI
TL;DR: The state-of-the-art advancements in FSSCs are reviewed to provide new insights on mechanisms, emerging electrode materials, flexible gel electrolytes and novel cell designs.
Abstract: Flexible solid-state supercapacitors (FSSCs) are frontrunners in energy storage device technology and have attracted extensive attention owing to recent significant breakthroughs in modern wearable electronics In this study, we review the state-of-the-art advancements in FSSCs to provide new insights on mechanisms, emerging electrode materials, flexible gel electrolytes and novel cell designs The review begins with a brief introduction on the fundamental understanding of charge storage mechanisms based on the structural properties of electrode materials The next sections briefly summarise the latest progress in flexible electrodes (ie, freestanding and substrate-supported, including textile, paper, metal foil/wire and polymer-based substrates) and flexible gel electrolytes (ie, aqueous, organic, ionic liquids and redox-active gels) Subsequently, a comprehensive summary of FSSC cell designs introduces some emerging electrode materials, including MXenes, metal nitrides, metal–organic frameworks (MOFs), polyoxometalates (POMs) and black phosphorus Some potential practical applications, such as the development of piezoelectric, photo-, shape-memory, self-healing, electrochromic and integrated sensor-supercapacitors are also discussed The final section highlights current challenges and future perspectives on research in this thriving field

1,210 citations