Enhanced catalytic activity and stability for the electrooxidation of formic acid on lead modified shape controlled platinum nanoparticles

Abstract

High catalytic activity for formic acid oxidation reaction (FAOR) is demonstrated in Pb modified shape-controlled Pt nanoparticles (NPs). Cyclic voltammetry is used to follow the effective modification of Pt NPs by Pb. Octahedral shaped Pt NPs (having a (111) preferential surface structure) modified by Pb are proved the most active electrocatalyst studied towards FAOR and display a catalytic activity of c.a. 7 mA cm-2 at 0.5 V in 0.1 M formic acid solution. This current density represents an enhancement factor 29.5 with respect to the unmodified Pt NPs and this is 2.7 and 2.3 times higher than that found on Tl /100-Pt NPs and Sb /111-Pt NPs, respectively, some of the most active electrocatalysts based on adatoms modified Pt NPs reported so far. This outstanding activity is displayed at maximum Pb coverage and also confers a wide electrocatalyst stability over the entire potential range studied. FAOR is also studied using scanning electrochemical microscopy (SECM) by the micropipette delivery/substrate collection (MD/SC) working mode as a preliminary rapid test to identify active electrocatalysts. In

Oxygen crossover effect on palladium and platinum based electrocatalysts during formic acid oxidation studied by scanning electrochemical microscopy

“…Nevertheless, the case of oxygen crossover effect during FAOR on Pd, Pt and Pd-Pt alloys, which we study herein is, so far, a non-described phenomenon in electrocatalysts for FAOR. Therefore, the main goal of this article is to mimic the effect of O 2 crossover from the cathode side towards the anode side in DFAFCs, using the micropipette delivery/substrate collection (MD/SC) mode of SECM, which is based on the transfer of a neutral species by diffusion across an immiscible liquid/liquid interface as sketched for HCOOH in Figure 1 [ 36,38,52 ]. It is worth noting that the acidic solution used as aqueous phase outside the micropipette should not be totally deaerated in order to study the effect of simultaneous reactions, FAOR and ORR, on Pd, Pt and Pd-Pt alloys.…”

“…A C C E P T E D M A N U S C R I P T 11 of synthesized NPs was performed by adsorbing CO at the NPs surface [ 38,53 ]. After that, a linear voltammetry at 20 mV s -1 with an upper potential limit of 0.9 V was performed for a complete electrochemical oxidation-stripping of CO from the NPs surface [ 57 ].…”

“…is delivered within the bulk solution by crossing the liquid-liquid interface between two immiscible phases, DCE and H 2 O, in this case. The current collection for FAOR (difference between the maximum oxidation current displayed at the catalyst spot location and the background current at the same scanned line in the SECM image at a given tip-substrate distance) is calculated to quantitatively compare the catalytic activity of all different materials studied by SECM [ 38,59 ] (see later Table 1).…”

Correlation between Formic Acid Oxidation and Oxide Species on Pt(Bi)/GC and Pt/GC Electrode through the Effect of Forward Potential Scan Limit

“…Further improving of Pt electrochemical activity for FAO with addition of metals, such as Pb, Cu, Au, Ni, Ag, Sn, and Co, has been performed [11][12][13][14][15], and, among bimetallic catalysts, Pt-Bi is the most extensively studied. Different types of Pt-Bi catalysts obtained by various methods have been reported, such as the synthesis method capable of producing intermetallic Pt-Bi nanoparticles 1−3 nm in diameter [16] or Pt-Bi intermetallics with a particle size of 20−100 nm with certain preferential surface structures [17], Pt-Bi alloy nanoparticles following the cathodic corrosion method [18], electrochemically codeposited Pt-Bi [19], or Pt modified by Bi either by UPD or by irreversible adsorption [20,21].…”

Shape-controlled metal nanoparticles for electrocatalytic applications

“…On the other hand, the use of certain adatoms to selectively decorate the surface of different shape-controlled metal nanoparticles towards formic acid electrooxidation has been also explored in different contributions. Feliu and co-workers employed different adatoms including Bi [194,195], Pd [196,197], Sb [198], and more recently Tl [199] and Pb [200] as surface modifiers on different shaped Pt nanoparticles. Sun and co-workers also used Bi [194] and Au [201] with THH Pt nanocrystals.…”