Electrocatalytic oxidation of ethanol and ethylene glycol on cubic, octahedral and rhombic dodecahedral palladium nanocrystals

Cubic, octahedral and rhombic dodecahedral Pd nanocrystals were synthesized and examined as nanocatalysts for electro-oxidation of ethanol and ethylene glycol. Combined electrochemical measurements and density functional theory calculations reveal that nanofacet-dependent affinity and reactivity of OHads and COads are closely linked to the C2 alcohol oxidation activities, with the highest reactivity found on the Pd nanocubes bounded by {100} facets

Recent Advances on Electro-Oxidation of Ethanol on Pt- and Pd-Based Catalysts : From Reaction Mechanisms to Catalytic Materials

Article published in: Catalysts 2015, 5, 1507-1534; doi:10.3390/catal5031507</p

Combined Surface-Enhanced Infrared Spectroscopy and First-Principles Study on Electro-Oxidation of Formic Acid at Sb-Modified Pt Electrodes

In situ electrochemical surface-enhanced infrared absorption spectroscopy (EC-SEIRAS) together with a periodic density functional theory (DFT) calculation has been initially applied to investigate the mechanism of formic acid electro-oxidation on Sb-modified Pt (Sb/Pt) electrode. EC-SEIRAS measurement reveals that the main formic acid oxidation current on Sb/Pt electrode is ca. 10-fold enhanced as compared to that on clean Pt electrode, mirrored by nearly synchronous decrease of the CO and formate surface species, suggesting a “non-formate” oxidation as the main pathway on the Sb/Pt electrode. On the basis of the calculations from periodic DFT, the catalytic role of Sb adatoms can be rationalized as a promoter for the adsorption of the CH-down configuration but an inhibitor for the adsorption of the O-down configuration of formic acid, kinetically facilitating the complete oxidation of HCOOH into CO2. In addition, Sb modification lowers the CO adsorption energy on Pt, helps to mitigate the CO poisoning effect on Pt

Electrocatalysis of formic acid on palladium and platinum surfaces : from fundamental mechanisms to fuel cell applications

Article published in: Phys. Chem. Chem. Phys., 2014, 16, 20360--20376</p

B‑Doped Pd Catalyst: Boosting Room-Temperature Hydrogen Production from Formic Acid–Formate Solutions

Facile production of hydrogen at room temperature is an important process in many areas including alternative energy. In this Communication, a potent boron-doped Pd nanocatalyst (Pd-B/C) is reported for the first time to boost hydrogen generation at room temperature from aqueous formic acid–formate solutions at a record high rate. Real-time ATR-IR spectroscopy is applied to shed light on the enhanced catalytic activity of B-doping and reveals that the superior activity of Pd-B/C correlates well with an apparently impeded CO_ad accumulation on its surfaces. This work demonstrates that developing new anti-CO poisoning catalysts coupled with sensitive interfacial analysis is an effective way toward rational design of cost-effective catalysts for better hydrogen energy exploitation

From HCOOH to CO at Pd Electrodes: A Surface-Enhanced Infrared Spectroscopy Study

The decomposition of HCOOH on Pd surfaces over a potential range of practical relevance to hydrogen production and fuel cell anode operation was probed by combining high-sensitivity in situ surface-enhanced IR spectroscopy with attenuated total reflection and thin-layer flow cell configurations. For the first time, concrete spectral evidence of COad formation has been obtained, and a new main pathway from HCOOH to COad involving the reduction of the dehydrogenation product of HCOOH (i.e., CO2) is proposed

Surface-Enhanced Infrared Spectroscopic Study of a CO-Covered Pt Electrode in Room-Temperature Ionic Liquid

ATR-SEIRAS is extended for the first time to study potential-induced surface and interface structure variation of a CO-covered Pt electrode in a room-temperature ionic liquid of <i>N</i>-butyl-<i>N</i>-methyl-piperidinium bis­((trifluoromethyl)­sulfonyl)­imide (or [Pip₁₄]­[TNf₂]). Owing to a wide effective potential window of [Pip₁₄]­[TNf₂], a gradual conversion from bridged CO_ad (CO_B) to terminal CO_ad (CO_L) is observed in response to positively going potentials, suggesting that [Pip₁₄]⁺ may be involved in a strong electrostatic interaction with the CO_ad. This site conversion enables the ratio of the apparent absorption coefficient of CO_L to that of CO_B to be determined. Also, the spectral results reveal the potential-dependent CO_ad frequency variations as well as the potential-induced interfacial ionic reorientation and movement at the Pt/CO/[Pip₁₄]­[TNf₂] interface

In Situ Surface-Enhanced IR Absorption Spectroscopy on CO Adducts of Iron Protoporphyrin IX Self-Assembled on a Au Electrode

The surface coordination chemistry of carbon monoxide with the reduced form (FeIIPP) of iron(III) protoporphyrin IX (FeIIIPP) monolayer self-assembled on a Au electrode in 0.1 M HClO4 was studied for the first time by using in situ ATR-surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS). Both mono- and biscarbonyl adducts [simplified as FeII(CO)PP and FeII(CO)2PP, respectively] were detected, depending on the history of potential control. Initially, the FeII(CO)PP predominates, and the intermediate transition potential for the conversion of FeII(CO)PP to FeIIIPP and CO was spectrally determined to be ca. 0.09 V (vs SCE). The ratio of FeII(CO)2PP and FeII(CO)PP increases after a potential excursion to a sufficiently positive value. FeII(CO)2PP is much more stable against its electro-oxidation to FeIIIPP than its counterpart FeII(CO)PP with increasing potential. The observed change of coordination properties may be ascribed to an irreversible structural reorganization of the FePP adlayer caused by the potential excursion

A Study of NO Adducts of Iron Protoporphyrin IX Adlayer on Au Electrode with in Situ ATR-FTIR Spectroscopy

In situ attenuated total reflection (ATR) Fourier transform infrared (ATR-FTIR) spectroscopy has been applied to probe the coordination of nitric oxide to iron protoporphyrin IX (FePP) adlayer on Au (FePP/Au) electrodes in 0.1 M HClO4. On the basis of potential controlled ATR-FTIR spectra on independent FePP/Au electrodes and multistep ATR-FTIR measurement on one FePP/Au electrode, for the first time, up to three IR bands corresponding to three types of nitrosyl adducts of FePP have been identified with their intensities (concentrations) varied with the potential applied. The 1915-cm-1 band, which shows up at relatively positive potentials and stabilizes in a rather narrow potential range, can be reasonably assigned to the FeIII(NO)(OH2)PP species or to its isoelectronic format FeII(NO)+(OH2)PP. The other two bands with much lower frequencies, which can stabilize over a much wider potential range and which can exhibit nearly opposite potential-dependent intensities, are basically characteristic of nitrosyl adducts of ferrous FePP. One band at ca. 1670 cm-1 with insignificant Stark effect can be attributed to FeII(NO)PP. The other above 1705 cm-1 with significant Stark effect could be ascribed to FeII(NO)2PP. The multinitrosyl adductions may be caused by the largely inhomogeneous structure of the FePP adlayer on Au electrodes