Influence of the preparation conditions ofPd‐ZrO₂andAuPd‐ZrO₂nanoparticle–decorated functionalisedMWCNTs: Electron spectroscopy study aided with theQUASES

Abstract

The Pd, AuPd, and ZrO2 nanoparticle–decorated functionalised multiwalled carbon nanotubes (f‐MWCNTs) were reported as efficient catalysts of formic acid (FA) electro‐oxidation. Different preparation conditions influence their chemical and structural properties analysed by X‐ray photoelectron spectroscopy aided with the quantitative analysis of surfaces by electron spectroscopy. Different reduction procedures such as NaBH4, a polyol microwave‐assisted method (PMWA), and a high pressure microwave reactor (HPMWR) were applied for decorating ZrO2/f‐MWCNTs with Pd and AuPd nanoparticles. The ZrO2 nanoparticles are attached through oxygen groups to the surface of f‐MWCNTs. In NaBH4 and HPMWR procedures, Pd nanoparticles precipitate predominantly on ZrO2 of nearly nominal stoichiometry, whereas in PMWA procedure, Pd and AuPd nanoparticles precipitate predominantly on the surface of f‐MWCNTs, bridging with oxygen groups and ZrOx (x < 2) and leading to Pd‐O‐Zr phase formation. Strong reducing procedures (NaBH4 and FA) led to smaller Pd nanoparticle size, Pd oxide content, and PdOx overlayer thickness in contrary to weak reduction procedures (HPMWR and PMWA). The highest content of Pd‐O‐Zr phase appeared for Pd predominant precipitation on ZrO2 nanoparticles (HPMWR) in contrary to Pd and AuPd predominant precipitation on surface of f‐MWCNTs (NaBH4 ~ FA > PMWA). Larger content of Pd‐O‐Zr phase in AuPd‐decorated ZrO2/f‐MWCNTs in contrary to Pd‐decorated sample (PMWA) could be justified by different electronic properties of nanoparticles. The FA treatment of Pd and AuPd‐ZrO2/f‐MWCNTs samples provided decreasing Pd oxide content, overlayer thickness, nanoparticle size, increasing nanoparticle surface coverage and density, amount of Pd‐O‐Zr, what results from reduction of oxygen groups bridging with Pd and ZrOx nanoparticles, also through Pd‐O‐Zr phase.

Investigating the structure of the oxide on Ni‐Cr‐Mo alloys while presenting a method for analysis of complex oxides using QUASES

“…For the example used in this paper, the universal cross‐section was utilized in all instances for the analysis of Cr and Mo peaks. The universal cross‐section has been proven to describe the cross‐section for most metals and their respective oxides with sufficient accuracy 41 and has been utilized in many studies 19,22,48,49 . For other solids (i.e., Al, Si, SiO 2 , Ge, and polymers), an alternative cross‐section is required to describe the electron energy loss processes accurately.…”

“…The universal cross-section has been proven to describe the cross-section for most metals and their respective oxides with sufficient accuracy 41 and has been utilized in many studies. 19,22,48,49 For other solids (i.e., Al, Si, SiO 2 , Ge, and polymers), an alternative cross-section is required to describe the electron energy loss processes accurately. Using the reflected electron energyloss spectroscopy (REELS) method of cross-section determination, Tougaard demonstrated that the cross-section for Si has a distinct plasmon peak at 16.8 eV.…”

“…Analyzing the inelastic background signal has been useful in studies including, but not limited to, surface oxides, nanoparticles, corrosion, and adsorption processes 19–32 . In a series of publications by Grosvenor et al, QUASES was used to study the gas‐phase oxidation of pure Fe 19,20,25–27 .…”

“…Analyzing the inelastic background signal has been useful in studies including, but not limited to, surface oxides, nanoparticles, corrosion, and adsorption processes. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] In a series of publications by Grosvenor et al, QUASES was used to study the gas-phase oxidation of pure Fe. 19,20,[25][26][27] The authors were able to model the structure of various surface oxides and hydroxides (i.e., γ-Fe 2 O 3 , Fe 3 O 4 , FeO, FeOOH, Fe (OH) 2 ) as a function of exposure conditions, which included temperature, O 2 concentration, and exposure time.…”

Studies on Effect of Temperature On Carbonization of Silk (Bombyx Mori) And Its Application as Proximity Sensor

“…Additionally, the BE values increased for carbon nanostructures that contained electron-withdrawing groups such as defects (like pentagons and hexagons) and hydrogen [66][67][68][69]. The experiments conducted on various carbon nanomaterials revealed a separation value in the binding energy (BE) between C sp 2 and C sp 3 , which ranged from 0.6 eV to 1.35 eV [66,[70][71][72]. Diamond-like carbon (DLC) films were reported to have binding energy (BE) values of 0.6 eV [73] and 0.8 eV [70].…”