Synthesis and temperature-dependent evolution of the phase composition in palladium-containing silicon oxycarbide ceramics

Papakollu, Kousik; Moharana, Niraja; Kumar, Krishna; Lauterbach, Stefan; Kleebe, Hans‐Joachim; Ionescu, Emanuel; Kumar, Ravi

doi:10.1016/j.jeurceramsoc.2022.05.032

Cited by 6 publications

(4 citation statements)

References 46 publications

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“…4g). Although the deconvoluted C 1s peak showed C–C, 31,39 C–Si, 31,38 and C–O 38 bonds in as-pyrolyzed composite (Fig. 4c), however, only C–C bonds were observed in the annealed composite (Fig.…”

Section: Resultsmentioning

confidence: 96%

“…S4 †) revealed T and D ′′ bands, likely due to the existence of disordered sp 2 -sp 3 bonds, graphene edges, and pores. 38,39 The disorder-induced "D" band in graphitic materials corresponds to the T band in free carbon, a low-frequency Raman characteristic. It originates as a result of phonon scattering with disorder-and defect-induced modes.…”

Section: Phase Evolution Studiesmentioning

confidence: 99%

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New insights into the electrochemical performance of precursor derived Si(Nb)OC composites as anode materials for batteries

Vendra,

Singh,

Kumar

2023

RSC Adv.

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Section: Resultsmentioning

confidence: 96%

Section: Phase Evolution Studiesmentioning

confidence: 99%

New insights into the electrochemical performance of precursor derived Si(Nb)OC composites as anode materials for batteries

Vendra,

Singh,

Kumar

2023

RSC Adv.

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“…Continuous graphene length, including tortuosity ( L eq ) [ 57 ], the average distance between defects ( L D ) [ 55 ], and 3D-ordering of the graphene layers (Δ W 2 D −1 ) [ 53 ] are other less common parameters. These Raman parameters have started appearing in recent literature for SiOC-derived materials [ 20 , 58 , 59 , 60 , 61 ]. However, to the best of our knowledge, it is the first time that these parameters have been employed in SiOC-CD materials.…”

Section: Resultsmentioning

confidence: 99%

Highly Porous Carbon Materials Derived from Silicon Oxycarbides and Effect of the Pyrolysis Temperature on Their Electrochemical Response

Merida,

Colomer,

Rubio

et al. 2023

IJMS

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The design of a material porous microstructure with interconnected micro-meso-macropores is a key issue for the successful development of carbon-derived materials for supercapacitor applications. Another important issue is the nature of these carbon materials. For those reasons, in this study, novel hierarchical micro-meso-macroporous silicon oxycarbide-derived carbon (SiOC-DC) was obtained via chlorine etching of carbon-enriched SiOC prepared via pyrolysis (1100–1400 °C) of sol-gel triethoxysilane/dimethyldiphenysiloxane hybrids. In addition, and for the first time, non-conventional Raman parameters combined with the analysis of their microstructural characteristics were considered to establish their relationships with their electrochemical response. The sample pyrolyzed at 1100 °C showed planar and less-defective carbon domains together with the largest specific surface area (SSA) and the highest volume of micro-meso-macropores, which upgraded their electrochemical response. This sample has the highest specific capacitance (Cs = 101 Fg−1 (0.2 Ag−1)), energy (Ed = 12–7 Wh−1 kg−1), and power densities (Pd = 0.32–35 kw kg−1), showing a good capacitance retention ratio up to 98% after 10,000 charge–discharge cycles at 0.5 Ag−1. At a pyrolysis temperature ≥ 1200 °C, the carbon domains were highly ordered and tortuous with a high degree of interconnection. However, SSA and pore volumes (micro-meso-macropores) were significantly reduced and downgraded the Cs, Ed, and Pd values.

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“…Such graphitization of carbon by transition metals was reported earlier. 49,50 It was understood that elements such as vanadium which readily form carbides can catalyze graphitization of carbon by the carbide formation− decomposition mechanism. 51 Furthermore, the evolution of the Raman parameters with respect to heat treatment temperature was analyzed.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Effect of Structural Changes at Various Length Scales in SiVOC Ceramic Nanocomposites on Electrocatalytic Performance for the Oxygen Reduction Reaction

Papakollu

Bhardwaj

Ionescu

et al. 2023

ACS Appl. Mater. Interfaces

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Polymer-derived processing of ceramics (PDC) is an efficient technique to prepare porous nanocomposites with precise control over their phase composition and in relation to the Si-based ceramic matrix containing free carbon. The microstructure of these nanocomposites can be fine-tuned at the molecular scale for obtaining necessary properties by tailoring the chemical configuration of the preceramic polymer. In the present work, vanadiumbased nanocomposites were synthesized as oxygen reduction reaction (ORR) catalysts with the objective of elucidating the effect of microstructure changes on catalytic efficiency. For this purpose, a single-source precursor (SSP) was synthesized by crosslinking phenyl-and hydrido-substituted polysiloxane and vanadium acetylacetonate followed by pyrolysis at 1100 °C. The resulting solid was composed of sparsely distributed nanodomains of vanadium carbide (VC) crystals precipitated within an amorphous silicon oxycarbide (−Si−O−C−) matrix. High-temperature treatment of the pyrolyzed samples beyond 1300 °C induced the crystallization of β-SiC as well as VC. Furthermore, Raman spectroscopy confirmed the segregation of sp 2 -hybridized, turbostratic free carbon. The samples exposed to 1300 °C revealed a specific surface area of 239 m 2 /g. The electrocatalytic activity of the sample heat-treated at 1300 °C showed the best performance with respect to the ORR performance with onset potential (E o ) and half-wave potential (E 1/2 ) values of 0.81 and 0.72 V, respectively. In addition, improved kinetics with a Tafel slope of 57 mV/dec and enhanced current density in the diffusion-controlled region (I d ) of 3.7 mA/cm 2 were observed for this sample. The increase in E o was attributed to the optimal interfacial characteristics between the VC and SiOC matrix with better embedment of VC with free carbon through V−C bonds. The higher E 1/2 and faster kinetics are because of the higher electronic conductivity caused by the free carbon effectively connecting metallic VC crystallites. Besides, the higher specific surface area of this sample enhanced I d .

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Synthesis and temperature-dependent evolution of the phase composition in palladium-containing silicon oxycarbide ceramics

Cited by 6 publications

References 46 publications

New insights into the electrochemical performance of precursor derived Si(Nb)OC composites as anode materials for batteries

New insights into the electrochemical performance of precursor derived Si(Nb)OC composites as anode materials for batteries

Highly Porous Carbon Materials Derived from Silicon Oxycarbides and Effect of the Pyrolysis Temperature on Their Electrochemical Response

Effect of Structural Changes at Various Length Scales in SiVOC Ceramic Nanocomposites on Electrocatalytic Performance for the Oxygen Reduction Reaction

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