Pt(Ni) electrocatalysts for methanol oxidation prepared by galvanic replacement on TiO2 and TiO2–C powder supports

Georgieva, J.; Valova, E.; Mintsouli, I.; Sotiropoulos, S.; Tatchev, Dragomir; Armyanov, S.; Hubin, Annick; Dille, Jean; Hoell, Armin; Raghuwanshi, Vikram Singh; Karanasios, Nikolaos; Malet, Loïc

doi:10.1016/j.jelechem.2015.07.001

Cited by 26 publications

(26 citation statements)

References 53 publications

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“…As pointed out by Podlovchenko and co-workers [119] and Sotiropoulos and co-workers [68,107,108], in such systems the noble metal (here Pt) is expected to deposit not only on sacrificial M islands (here Cu) but also on nearby bare C locations; this is because the substrate is an electronic conductor and electrons released by the dissolution of Cu can travel to nearby locations where Pt ions may be reduced and deposited as metallic Pt. Note that this effect is expected to occur at a lower extent in catalysts prepared via the Cu upd method since the whole process of replacing a single monolayer is restricted both in time and space; also, in principle, it should be absent if the support of M is an insulator or semiconductor (e.g., TiO 2 or WO 3 , as in [111,112,151]) or if the particles are prepared before the addition of the support (see, for example, [152]. Figure 7A,B presents Pt(Cu) and Pt(Ni) nanoparticles resulting from the (partial) galvanic replacement of electrolessly prepared Cu/C and Ni/C precursors [107,110].…”

Section: Types Of Support Methods Of Less Noble Metal Preparation/dementioning

confidence: 99%

“…Note that this effect is expected to occur at a lower extent in catalysts prepared via the Cu upd method since the whole process of replacing a single monolayer is restricted both in time and space; also, in principle, it should be absent if the support of M is an insulator or semiconductor (e.g., TiO2 or WO3, as in [111,112,151]) or if the particles are prepared before the addition of the support (see, for example, [152]. Figure 7A,B presents Pt(Cu) and Pt(Ni) nanoparticles resulting from the (partial) galvanic replacement of electrolessly prepared Cu/C and Ni/C precursors [107,110].…”

Section: Types Of Support Methods Of Less Noble Metal Preparation/dementioning

confidence: 99%

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Electrocatalysts Prepared by Galvanic Replacement

et al. 2017

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Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, M noble , when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mM noble n+ → nM m+ + mM noble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases) hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a M noble-rich shell and M-rich core (denoted as M noble (M)) leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition) as well as the various options for the support are also reviewed. 1. Principle of Galvanic Replacement/Deposition 1.1. Thermodynamic Considerations When a metal, M (e.g., Cu, Fe, Co, Ni, Al, etc.), is immersed in a solution containing ions of a more noble metal, M noble n+ (e.g., Pt, Au, Pd, Ag, Ru, Ir, Rh, Os, etc.-i.e., a metal with a higher standard potential) then, due to the difference in their standard electrochemical potentials, E 0 noble − E 0 > 0, and provided that the ionic form of M is stable under the given experimental conditions (of temperatue, pH, complexing agents etc.), the following reaction is thermodynamically favored and can take place spontaneously: M noble n+ + n/m M → M noble + n/m M m+ (1) This reaction, which bears similarities with transmetalation reactions between metal complexes [1] and is also known as immersion plating [2] in the plating industry and galvanic replacement [3] in materials chemistry, can be considered to originate from the coupling of the following two half-reactions: M noble n+ + ne − ↔ M noble (E 0 noble) (2) M m+ + me − ↔ M (E 0) (3)

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Section: Types Of Support Methods Of Less Noble Metal Preparation/dementioning

confidence: 99%

Section: Types Of Support Methods Of Less Noble Metal Preparation/dementioning

confidence: 99%

Electrocatalysts Prepared by Galvanic Replacement

et al. 2017

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“…These can be broadly classified as the ones involving modification of the material itself and those based on mixing it with a conducting material such as carbon. The former route includes partial reduction to TiO 2-x (i.e., conversion to Ebonex ® -like materials-see for example [8,9]) or/and incorporating C (activated carbon, reduced graphene oxide or carbon nanotubes) in the material [10][11][12][13][14][15][16][17][18][19][20][21]; the latter modification route is based either on simply mixing the TiO 2 -based material with C [10][11][12][13][14][15][16] or adding the carbonaceous material in the reaction mixture of catalyst preparation or modification (sol-gel chemistry, wet reduction chemistry, carbonization, etc.) [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…TiO 2 has been used as a support in Pt-based MOR catalysts, mainly due to its apparent ability to oxidize CO at nearby Pt locations in the dark and, also, due to the possibility of further CO photo-oxidation upon its illumination [30]. Among the various methods to deposit Pt on TiO 2 or TiO 2 -based supports [10][11][12][13][14][15][16][17][18][19][20][21] (namely wet chemistry reduction, sol-gel co-deposition, etc. ), UV photo-deposition (reduction of Pt by photo-generated electrons at the surface of illuminated TiO 2 ) is an environmentally friendly and cost effective option [8,13,14,31].…”

Section: Introductionmentioning

confidence: 99%

“…), UV photo-deposition (reduction of Pt by photo-generated electrons at the surface of illuminated TiO 2 ) is an environmentally friendly and cost effective option [8,13,14,31]. At the same time, in most Pt-TiO 2 systems containing carbon (with the exception of [10,11,15,16,31]) either Pt-C was incorporated in TiO 2 or Pt was deposited on TiO 2 -C composites/mixtures, attenuating direct Pt-TiO 2 interactions. Furthermore, in none of those studies was the effect of added carbon studied systematic, despite the fact that carbon optimization is important to minimize corrosion and light attenuation effects while at the same time provide adequate conductivity.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes

et al. 2020

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The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and C nanoparticles (Vulcan XC72R) are added by simple ultrasonic mixing. The optimum C÷Ti atom ratio of the prepared catalyst for methanol electro-oxidation is found to be 1.5, resulting from the interplay of C properties (increased electronic conductivity and methanol adsorption), those of TiO2 (synergistic effect on Pt and photo-activity), as well as the catalyst film thickness. The intrinsic catalytic activity of the best Pt-TiO2/C catalyst is better than that of a commercial Pt/C catalyst and could be further improved by nearly 25% upon UV illumination, whose periodic application can also limit current deterioration.

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Bimetallic Catalysts for Sustainable Chemistry: Surface Redox Reactions For Tuning The Catalytic Surface Composition

2023

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The development of a bimetallic catalyst for a given reaction requires not only the selection of the appropriate metals M1 and M2 but also the control as far as possible of the distribution of the two metals together and at the support surface in the case of supported catalysts.Preparation methods using redox reactions specifically enable the deposition of a second metal M2 at the surface of monometallic M1 nanoparticles, leading in most cases to core-shell nanoparticles with strong metal-metal interactions. Various methods are possible depending on the electrochemical potentials of the species involved: either a direct redox reaction, also named galvanic replacement, or the reduction of an intermediate reducing agent activated at the surface of M1. In this minireview, the fundamental bases of the preparation of bimetallic catalysts by both types of redox reactions and the recent advances in that domain are described.

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Pt(Ni) electrocatalysts for methanol oxidation prepared by galvanic replacement on TiO2 and TiO2–C powder supports

Cited by 26 publications

References 53 publications

Electrocatalysts Prepared by Galvanic Replacement

Electrocatalysts Prepared by Galvanic Replacement

The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes

Bimetallic Catalysts for Sustainable Chemistry: Surface Redox Reactions For Tuning The Catalytic Surface Composition

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