Xianjue Chen

Xianjue Chen

Xianjue Chen

ARC DECRA Fellow

Contact details

Email: xianjue.chen@unsw.edu.au

Office

Dalton 125

 


Biographical Details

  • B.E. (2008) and M.E. (2010) from Harbin Institute of Technology, China
  • PhD in Chemistry (July 2014) from the University of Western Australia
  • Research Associate (2013-2015) at Flinders University, Australia
  • Research Fellow (2015-2017) in the Center for Multidimensional Carbon Materials, Institute for Basic Science, South Korea
  • Research Associate / ARC DECRA Fellow (2017-present) at the University of New South Wales

Current Research Efforts

  • Carbon-based materials including graphene, graphene oxide, reduced graphene oxide, amorphous carbon, "curved" carbon, diamond, fullerenes, nanotubes, nano-onions, “peapods”, foams, films and membranes, as well as relevant 2D materials and nanostructures
  • 2D Membrane technologies for molecular sieving 
  • Material innovation for energy-related applications 
  • Chemical process intensifications

Selected Publications

For full list of publications, please visit: Google Scholar 

  • S. Wu, J. Mo, Y. Zeng, Y. Wang, A. Rawal, J. Scott, Z. Su, W. Ren, S. Chen, K. Wang, W. Chen, Y. Zhang, C. Zhao, X. Chen*, Shock exfoliation of graphene fluoride in microwave, Small (2020) 16, 1903397. https://doi.org/10.1002/smll.201903397

An unprecedented microwave‐based strategy is developed to facilitate solid‐phase, instantaneous delamination and decomposition of graphite fluoride (GF) into few‐layer, partially fluorinated graphene. The shock reaction occurs (and completes in few seconds) under microwave irradiation upon exposing GF to either “microwave‐induced plasma” generated in vacuum or “catalyst effect” caused by intense sparking of graphite at ambient conditions. A detailed analysis of the structural and compositional transformations in these processes indicates that the GF experiences considerable exfoliation and defluorination, during which sp2‐bonded carbon is partially recovered despite significant structural defects being introduced. The exfoliated fluorinated graphene shows excellent electrochemical performance as anode materials in potassium ion batteries and as catalysts for the conversion of O2 to H2O2. This simple and scalable method requires minimal energy input and does not involve the use of other chemicals, which is attractive for extensive research in fluorine‐containing graphene and its derivatives in laboratories and industrial applications.

 

  • B. Das*, C. Jia, K. Ching, M. Bhadbbade, X. Chen*, S. B. Colbran, C. Zhao, Ruthenium Complexes in Homogeneous and Heterogeneous Catalysis for Electroreduction of CO2, ChemCatChem (2020) 12, 1292-1296. https://doi.org/10.1002/cctc.201902020

We have studied two structurally related, water‐insoluble ruthenium complexes [RuII(tpy*)(phenCO2)](PF6) () (tpy*=5,4′,5′′‐tri‐tert‐butyl‐2,2′;6′,2′′‐terpyridine; phenCO2H=1,10‐phenanthroline‐2‐carboxylic acid) and [RuII(tpy)(dmphen)(Cl)](PF6) () (tpy=2,2′;6′,2′′‐terpyridine; dmphen=2,9‐dimethyl‐1,10‐phenanthroline, also known as neocuproine) and their electrocatalytic activity for CO2 reduction in acetonitrile and after immobilization on the reduced graphene oxide (rGO) in water (pH 7.2). Under homogeneous conditions (in CO2 saturated acetonitrile solution), characteristic major CO2 reduction waves indicate ∼280 mV lower overpotential upon changing the catalyst from to 2. The higher CO2 electroreduction performance of is also reflected on the heterogeneous rGO surfaces.

 

  • X. Chen, X. Bo, W. Ren, S. Chen, C. Zhao, Microwave-assisted shock synthesis of diverse ultrathin graphene-derived materials, Mater. Chem. Front. (2019) 3, 1433. https://doi.org/10.1039/C9QM00113A

A paradigm shift is happening in graphene-related research from fundamental studies to the mass production and uptake of the materials into practical applications. Controlled conversion of the single-layer, pre-oxidised form of graphene is a promising pathway for the large-scale synthesis of graphene-like materials and derivatives. In this work, we report a strategy based on solid-state, shock reaction enabled by microwave-induced plasma for the ultrafast conversion of graphene oxide to ultrathin, defective carbon platelets, without pre-heating or use of any form of “catalyst”. This strategy is versatile, allowing instantaneous embedment of ultrafine, uniformly dispersed metal/metal-alloy nanoparticles into the carbon, featuring various nanostructures, from “core–shell” to “hollow”. The synthesised metal nanoparticle embedded 2D carbon can be directly used as a catalyst that shows enhanced water oxidation activity. Controlled doping of heteroatoms, i.e. nitrogen, sulfur and phosphorus, in the carbon is also demonstrated. This approach is simple and robust, potentially suitable for the mass production of a collection of new carbon-based materials with intriguing properties.

 

  • Zang, J. Toster, B. Das, R. Gondosiswanto, S. Liu, P. K. Eggers, C. Zhao, C. L. Raston, X. Chen*, p-Phosphonic acid calix[8]arene mediated synthesis of ultralarge, ultrathin, single-crystal gold nanoplatelets, Chem. Commun. (2019) 55, 3785. https://doi.org/10.1039/C8CC10145K

Single-crystal Au nanoplatelets, as large as 28 μm in cross section and as thin as 6 nm, are generated by bubbling hydrogen gas into an aqueous solution of HAuCl4 in the presence of p-phosphonic acid calix[8]arene, which acts as both a catalyst and stabiliser. The use of the ultrathin Au nanoplatelets in oxygen gas sensing has also been established.

 

  • X. Chen*, X. Deng, N. Y. Kim, Y. Wang, Y. Huang, L. Peng, M. Huang, X. Zhang, X. Chen, D. Luo, B. Wang, X. Wu, Y. Ma, Z. Lee, R. S. Ruoff, Graphitization of graphene oxide films under pressure, Carbon (2018) 132, 294. https://doi.org/10.1016/j.carbon.2018.02.049

Lightweight, flexible graphite foils that are chemically inert, high-temperature resistant, and highly electrically and thermally conductive can be used as component materials in numerous applications. “Graphenic” foils can be prepared by thermally transforming graphene oxide films. For this transformation, it is desirable to maintain a densely packed film structure at high heating rates as well as to lower the graphitizing temperatures. In this work, we discuss the pressure-assisted thermal decomposition of graphene oxide films by hot pressing at different temperatures (i.e., 300 °C, 1000 °C, or 2000 °C). The films pressed at 1000 °C or 2000 °C were subsequently heated at 2750 °C to achieve a higher degree of graphitization. The combination of heating and pressing promotes the simultaneous thermal decomposition and graphitic transformation of G-O films. Films pressed at 2000 °C as well as films further graphitized at 2750 °C show high chemical purity, uniformity, and retain their flexibility. For films pressed at 2000 °C and then further heated at 2750 °C, the mechanical performances outperform the reported values of the “graphite” foils prepared by calendering exfoliated graphite flakes; the electrical conductivity is ∼3.1 × 105 S/m and the in-plane thermal conductivity is ∼1.2 × 103 W/(m·K).

  

  • X. Chen, W. Li, D. Luo, M. Huang, X. Wu, Y. Huang, S. H. Lee, R. S. Ruoff, Controlling the thickness of thermally expanded films of graphene oxide, ACS Nano (2017) 11, 665. https://doi.org/10.1021/acsnano.6b06954

“Paper-like” film material made from stacked and overlapping graphene oxide sheets can be exfoliated (expanded) through rapid heating, and this has until now been done with no control of the final geometry of the expanded graphene oxide material, i.e., the expansion has been physically unconstrained. (As a consequence of the heating and exfoliation, the graphene oxide is “reduced”, i.e., the graphene oxide platelets are deoxygenated to a degree.) We have used a confined space to constrain the expanding films to a controllable and uniform thickness. By changing the gap above the film, the final thickness of expanded films prepared from, e.g., a 10 μm-thick graphene oxide film, could be controlled to values such as 20, 30, 50, or 100 μm. When the expansion of the films was unconstrained, the final film was broken into pieces or had many cracks. In contrast, when the expansion was constrained, it never cracked or broke. Hot pressing the expanded reduced graphene oxide films at 1000 °C yielded a highly compact structure and promoted graphitization. Such thickness-controlled expansion of graphene oxide films up to tens or hundreds of times the original film thickness was used to emboss patterns on the films to produce areas with different thicknesses that remain connected “in plane”. In another set of experiments, we treated the original graphene oxide film with NaOH before its controlled expansion resulted in a different structure featuring uniformly distributed pores and interconnected layers as well as simultaneous activation of the carbon.

 

In this article, the concept of interfacial self-assembly, with a main focus on the self-assembly processes at liquid-based interfaces, is first briefly introduced. It is followed by a discussion on the factors that can influence the interfacial self-assembly processes and therefore determine the final structures. An overview is then given on the recent advances in assembling novel multidimensional nanostructures by using different interfacial self-assembly strategies. A perspective is included at the end of the article.

The ability to scale up the production of chemically modified forms of graphene has led to intense interest in the manufacture and commercialization of graphene-based materials. Free-standing film-like materials comprised of stacked and overlapped platelets of graphene oxide (G-O) or thermally and electrically conductive reduced graphene oxide (rG-O) are potentially useful in various applications including filtration membranes, mechanical seals, protective layers, heating elements and components of batteries or supercapacitors as well as in electronics and optoelectronics. The advances in these applications require efficient and low-cost protocols for fabricating certain types of layered materials and, as such, protocols are urgently needed for the reduced forms of G-O. Here we report an efficient and straightforward method to thermally reduce thin films of stacked G-O platelets while still maintaining their structural integrity. By rapidly heating confined G-O films on a hot plate set to 400 °C under an atmosphere of air, G-O films were readily converted to intact, electrically conductive, reduced thin films. The structure and degree of reduction of the resulting free-standing rG-O films were found to be comparable to those obtained by slow annealing at the same temperature.

  • X. Chen, R. A. Boulos, A. D. Slattery, J. L. Atwood, C. L. Raston, Unravelling the structure of the C60 and p-But-calix[8]arene complex, Chem. Commun. (2015) 51, 11413. https://doi.org/10.1039/C5CC03941J

The structure of the C60 and p-But-calix[8]arene complex has been reinvestigated, showing an unprecedented continuous layered tetragonal array of fullerenes encapsulated by calixarenes. Electron diffraction data revealed the tetragonal symmetry, with a stepped structure observed by AFM and SEM, and the thickness of the basal plane was measured by XRD, as 2 nm. The molecular simulated arrangement of fullerenes accounts for the ability to take up to ca. 11% of fullerenes C70 in place of the smaller fullerene.

 

Centrifugation of the graphene oxide mediated Pickering emulsion results in transforming spheroidal toluene droplets into irregular polyhedral shapes, which can be preserved into a solid three-dimensional polyhedral-like graphene oxide network featuring facets and sharp edges, using a freeze-drying strategy.

 

  • M. Haniff Wahid, X. Chen*, C. T. Gibson, C. L. Raston, Amphiphilic graphene oxide stabilisation of hexagonal BN and MoS2 sheets, Chem. Commun. (2015) 51, 11709. https://doi.org/10.1039/C5CC02066B

A simple and scalable method has been developed for directly forming water-dispersible van der Waals solids involving mixing aqueous solution of graphene oxide (GO) with hexagonal boron nitride (BN) or molybdenum disulphide (MoS2) in N-methylpyrrolidone. The GO acts as an amphiphile in stabilising the colloidal solutions of the heterolaminar material in water.