The Catalyst Review May 2017 - 16

EXPERIMENTAL
The authors then go on to explore an alternative approach to functionalization of GO with Fc by forming covalent chemical bonds.
Covalent linkers are stronger than non-covalent interactions and are thus more resistant against Fc detaching from GO under battery
operation conditions. Moreover, covalent functionalization can provide a molecular-level distribution of Fc on GO, which improves
the utilization of the Fc molecules. The synthetic route to covalently anchor Fc on GO (GO-c-Fc) is shown in Figure 1a. Sulfur was
then uniformly deposited on GO-nc-Fc by the Na2Sx decomposition method. With a sulfur content of about 62 wt.%, the GO-ncFc-S material exhibits good specific capacity and rate capability, together with characteristic discharging-charging voltage profiles.
Notably, GO-c-Fc-S shows superior cycling stability, with 0.03% capacity decay per cycle over 500 cycles. DFT computational analysis,
in combination with XPS characterization (Figure 2), reveals that lithium polysulfides bind to Fc through cation-p interactions
between Li+ and the Cp ring, enabling a long-cycle life when implemented in Li-S batteries. Source: Mi Y, Liu W, Yang KR, et al.,
Angew. Chem. Int. Ed., 55: 14818 -14822.
Figure 1. Synthesis and characterization of Fc functionalized
GO assembled with covalent bonding (GO-c-Fc). a) Synthesis of
GO-c-Fc; b) TEM image of GO-c-Fc; c) EDX spectrum of GO-c-Fc;
d) CV curves of GO-c-Fc in 0.1 mol L-1 PBS at pH 7.4.

Figure 2. XPS and DFT study of the interactions between Li2S4
and GO-c-Fc. a) S 2p core level spectra of free Li2S4 and Li2S4
adsorbed on GO-c-Fc. b) Fe 2p and c) O 1s core level spectra of
GO-c-Fc and GO-c-Fc with adsorbed Li2S4. Optimized structures
and binding free energy changes (∆GB) of d) free LiSSH and e)
DME solvated LiSSH interacting with Fc.

Enhanced Lattice Oxygen Reactivity over Ni-Modified WO3-Based Redox Catalysts for Chemical
Looping Partial Oxidation of Methane...
The growing dominance of shale gas within the world energy sector has prompted intense interest in the development of efficient
and economical processes for converting methane into valuable chemicals and liquid fuels via generation of syngas. Currently,
methane steam reforming (MSR) is the most common process for transforming of methane to syngas but one that is quite costly
with respect to plant design and energy consumption. Other techniques under consideration include partial oxidation of methane
and two-step chemical looping-a process which uses the lattice oxygen from metal oxides (namely oxygen carriers) for syngas
generation and quality control. However, providing the optimum lattice oxygen to selectively produce syngas represents the major
challenge for the development of oxygen carrier materials in chemical looping processes. Herein, the authors describe the design
of a novel Ni-modified WO3-based oxygen carrier material
for chemical looping partial oxidation (CLPO) of methane in
Figure 1. (A) CH4-TPR mass spectra of WO3/Al2O3 and (B) CH4-TPR mass
which Al2O3 is used as a support to increase the dispersion of spectra of Ni0-5WOx/Al2O3.
the tungsten species. They then investigated how the nickel
species doped in the bulk of WO3 influences the tungsten−
oxygen bonds to increase the availability of lattice oxygen and
how the nickel species grafted on the surface catalyze and
accelerate the surface reaction.
NiyWOx/Al2O3 oxygen carrier particles were prepared
by continuous coprecipitation. WO3 loading was fixed to
40 wt. % for all of the samples. By varying of the amount
of nickel addition, Ni and W atomic ratios were tuned to be
0, 0.3, 0.5 and 1, respectively. Quantitative temperature16

The Catalyst Review

May 2017

The Catalyst Review May 2017

Table of Contents for the Digital Edition of The Catalyst Review May 2017