Mn-doped nickeltitanate (Ni1−xMnxTiO3) as a promising support material for PdSn electrocatalysts for methanol oxidation in alkaline media

Karazehir

J of Applied Polymer Sci

et al. 2023

In this study, Pt‐decorated poly(3,4‐ethylenedioxythiophene) (PEDOT) electrocatalyst was uniformly coated electrochemically reduced graphene oxide (ERGO) layer on glassy carbon electrode (GCE) has been created using appropriate procedures to facilitate the implementation of the methanol oxidation reaction (MOR). This multi‐layer catalyst was characterized in each production step via Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field‐emission scanning electron microscopy and energy‐dispersive x‐ray analysis (FESEM‐EDX) morphological analysis beside the electrochemical tests. The favorable structures of both ERGO and PEDOT increase conductivity and electrocatalytic activity toward methanol oxidation, which may create a suitable matrix for Pt loading thanks to the formation of much more active centers for methanol electrooxidation. The results demonstrate that the electrochemical surface area (ECSA) of Pt/PEDOT/ERGO/GCE was 39.1 m2 g−1, and it has a convenient mass activity (MA with 467 mA mg Pt−1) compared to that of commercial Pt/C. According to chronoamperometric analysis, the current density of Pt/PEDOT/ERGO/GCE was stable during the 1200 s of operation. It demonstrated remarkable stability with a final current density of 4.36 mA cm−2.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Production of Pt decorated poly(3,4‐ethylenedioxythiophene)/ERGO/GCEas an efficient catalyst for methanol oxidation reaction

Karazehir

J of Applied Polymer Sci

et al. 2023

“…Several attempts have been made to modify NiTiO 3 to tune its structure and surface activity by forming heterostructures or doping to study their modified optical properties, photo-degradation of dyes, methanol oxidation. NiTiO 3 / Ag 3 VO 4 , [12] Ag-doped NiTiO 3 , [13,14] Nb-doped NiTiO 3 , [15] PtÀ NiTiO 3 / C, [16] NÀ NiTiO 3 , [17] MnÀ NiTiO 3 , [18] carbon quantum dots on nickel titanate, [19] TiO 2 @NiTiO 3 and AuÀ TiO 2 @NiTiO 3 , [20] Cu 2 WS 4 /NiTiO 3 , [21] and NiTiO 3 /Cd 0.5 Zn 0.5 S. [22] Nonetheless, these modified systems have several downsides that limit the ability of these catalysts to be reliable candidates for photocatalytic water splitting. A set of factors curtailing their potential application for photocatalytic hydrogen production process include their inability to be stable during the hydrogen generation reaction, the z-scheme system being pH dependent, miss-match in band energies with cocatalysts, poor interfacial contacts, and their inability to form synergistic heterojunctions.…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Nickel Titanate Nanocubes with Ultra‐small Palladium and Platinum Nanocrystals to Promote Solar Hydrogen Generation under Visible Light

Moses,

Bastia,

Kumar

et al. 2023

ChemistrySelect

Modification of nickel titanate nanocubes with metal nanocrystals is a viable approach to build a Schottky heterojunction for efficient hydrogen generation. The deconvoluted XPS spectrum of Pt 4 f (peaks at 72.0 and 75.5 eV corresponding to Pt° and Pt2+) and Pd 3d3/2 (335.4 and 336.7 eV corresponding to Pd° and Pd2+) and presence of lattice fringes in HRTEM at 2.19 Å of Pd°, reveal the formation of heterojunction in Pd−NiTiO3 and Pt−NiTiO3 nanocubes. The solar hydrogen generation investigation exhibits 2‐fold enhancement in HER (130 and 165 μmol g−1 h−1 while using Pt−NiTiO3 and Pd−NiTiO3, respectively) than that of bare NiTiO3 (88 μmol g−1 h−1). The creation of heterojunctions between titanates and metal nanoparticles, facilitating efficient transport of photo‐generated electron to empty or partially filled d or f orbitals of metals, thereby lowering electron‐hole recombination rate, as revealed by shorter average lifetime 29 ns (Pd−NiTiO3) than 64 ns (NiTiO3). Further, the unison of faster charge transfer kinetics as revealed by the Nyquist plot, more negative flatband potential (Efb −0.3 vs. RHE) leading to appropriate band bending, reduced overpotential requirement, higher oxygen vacancies (19.46 %) and uniform dispersion of metal atoms on NiTiO3 surfaces that are acting as trapping centers etc. are enabling improved hydrogen generation in the case of Pd−NiTiO3.

ACS Appl. Energy Mater.

“…The usage of methanol as a fuel potentially overcomes many problems in H 2 –polymer electrolyte membrane fuel-cell technology; however, low efficiency and activity in direct methanol fuel cells remain as key bottlenecks. − This is explicitly referred to two issues: (1) the generation of stable and poisonous CO (for electrode) and (2) a higher anode overpotential as compared to the H 2 –polymer electrolyte membrane fuel cell. , Their combined effect drastically hampers the overall fuel-cell efficiency, although the equilibrium potential of anode reaction is nearly same as that of the H 2 –polymer electrolyte membrane fuel cell. Many reports suggest that Pt displays higher catalytic activity for methanol oxidation reaction (MOR); nevertheless, high cost and CO poisoning limit their widespread applications. , Recently, the research in development of noble-metal-free electrocatalysts for MOR has been extensively carried out. − Particularly, non-noble-metal composites like hydroxides, oxides, carbides, nitrides, phosphides, and chalcogenides were also reported for electrocatalytic applications, thus making non-noble-metal transition compounds a budding choice for MOR activity. − …”

Section: Introductionmentioning

confidence: 99%

Tuning the Ni/Co Ratios and Surface Concentration of Reduced Molybdenum States for Enhanced Electrocatalytic Performance in Trimetallic Molybdates: OER, HER, and MOR Activity

Maarisetty

Hang

Chou

et al. 2022

The heterogeneous nature of trimetallic catalyst systems comes with beneficial synergy for catalytic applications. Nonetheless, the challenges associated to validate and control the critical characteristics for enhanced electrocatalytic efficiencies are yet to be known. Herein, a genre of trimetallic catalysts were synthesized with Ni, Co, and Mo metals, whose morphological, structural, electronic, and interface properties depend on Ni/Co and Mo+4/Mo+5 ratios and the dominant element on the surface of the catalyst. The results suggest that introduction of a third metal, that is, Mo, is only beneficial when the Ni/Co ratio is optimally maintained. By combining the surface electronic and structural analyses such as electron energy loss spectroscopy, X-ray photoelectron spectroscopy, line scan, Raman spectra, and electrochemical data, it was realized that Mo and metallic Ni on the surface favor oxygen evolution reaction (OER), and methanol oxidation reaction (MOR) activity, respectively. Interestingly, the adsorbed water molecules were found to be vital for higher performance in both OER and MOR processes. The chronopotentiometry tests performed with the optimized catalyst Ni56Co7Mo37 for OER showed an overpotential around ca. 309 mV at ca. 720 mA·cm–2 even after 17 h (and also a Tafel slope of 60 mV·dec–1 at 10 mA·cm–2). The peak current density (from the cyclic voltammetry tests) in the optimized catalyst, that is, Ni66Co31Mo3 (for MOR), showed almost 300-fold higher activity in 1 M KOH + 1 M CH3OH solution when compared with only 1 M KOH. Further, comparative studies were also conducted with bimetallic catalysts of Ni, Co, and Mo to understand the better combinations for promoting OER, hydrogen evolution reaction, and MOR efficiencies. This work highlights the importance of maintaining the elemental composition ratios at the bulk and surface that lead to an active environment for OER and MOR processes and thereby opening gateways for a rational design of trimetallic electrocatalysts.