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Dendritic Pt nanostructures were prepared through electrodeposition on a substrate Pt electrode by applying square-wave potential method. It has been found that the as-prepared dendritic Pt nanostructure exhibited enhanced IR absorption with an enhancement factor up to 10 folds for adsorbed CO species. Such an enhanced in-situ FTIR spectroscopy (FTIRS) has been applied in studies of reaction mechanism of ammonia electrooxidation. From in-situ FTIR spectra recorded during ammonia electrooxidation, two characteristic IR bands at 1430 cm− 1 and between 1227 and 1250 cm− 1 were observed at low potential region (E 0.10 V vs. SCE), two IR bands at 2231 cm− 1 and 1236 cm− 1 were observed and ascribed respectively to N2O and NO2− species, which are the ultimate oxidation products detected under present investigation conditions. In addition to in-situ FTIR spectroscopy, online electrochemical mass spectroscopy (OEMS) was used to detect volatile products. The clear OEMS signals of m/e = 30 and m/e = 46 measured at potentials above − 0.5 V and − 0.30 V, respectively, indicate the production of N2 (IR inactive) and confirm the generation of N2O. Based on results of cyclic voltammetry, in-situ FTIRS and OEMS, the reaction mechanism is therefore elucidated with molecular details of intermediates and products involved in ammonia electrooxidation in alkaline solutions.

Electrocatalytic conversion of short-chain hydrocarbons is a promising alternative route of traditional heterogeneous catalytic conversion, due to the advantages of ease in selectivity tuning by electrode potential, effective utilization of renewable electricity and reducing CO2 emission. In this study, we investigated electrochemical conversion of ethane on Pt single crystal electrodes (Pt(S)[n(1 0 0) × (1 1 0)] and Pt(S)[n(1 0 0) × (1 1 1)] step surfaces) for the first time through the combination of cyclic voltammetry (CV) and in situ FTIR spectroscopy (In situ FTIRS). The results revealed that the reactivity of ethane conversion is highly sensitive to the surface structure of Pt, and the highest reactivity is achieved on Pt(1 0 0) surface. The introduction of step sites on (1 0 0) terrace will dramatically decrease the activity. Cyclic voltammogram of ethane oxidation on Pt(1 0 0) shows three oxidative peaks in positive-going potential scan and one oxidative peak in negative-going potential scan. In the potential range from 0.25 to 0.55 V, ethane can be dissociated to form mainly bridge-bonded CO, which can be further oxidized to CO2 at high potentials. The other promising pathway is without C C breaking, resulting in valuable products such as acetic acid and acetaldehyde at a relatively low potential of 0.50 V. At a potential over 0.60 V, bridge-bonded acetate was detected by in situ FTIR spectroscopy. Based on the experiment results, a possible reaction mechanism for the electrocatalytic conversion of ethane on Pt(1 0 0) was proposed.

In electrocatalysis, there are two mechanisms for hydrogenation reactions: Heyrovsky mechanism via the proton-electron transfer and Tafel mechanism via surface coupling with adsorbed hydrogen. In CO/CO2 electroreduction over copper catalysts, CH4 is a final product from the subsequent hydrogenation of carbon. In this work, by performing the constrained ab initio molecular dynamics simulations, we firstly identify that CH4 production on Cu(100) via the proton-electron transfer is more kinetically favored than via surface coupling, due to the negatively charged C atoms in CHx*. Our findings highlight the significance of proton-electron transfer in CO2 electroreduction, and help understand the essential difference between electrocatalysis and heterogeneous catalysis.

The bi-functional mechanism has been widely accepted for describing the binary catalysts in methanol electrooxidation, in which Pt sites can catalyze the methanol dehydrogenation and the second elements (e.g. Ru, Sn) can activate water to oxidants. However, in terms of binary PtRh, the surface Rh sites being identified not to be oxidized as easily as Ru, may participate in the dehydrogenation reaction at low potentials rather than just activate water. In this work, we investigate the roles of doped Rh on Pt(111) in methanol electrooxidation by density functional theory (DFT) calculations for the first time. We find that the methanol dehydrogenation activity is enhanced on Rh/Pt(111) because Rh can eliminate significantly the repulsive interaction between carbon fragment and H at the transition state. The formation potential of OH* on Rh/Pt(111) is 0.36 V (vs SHE) which is lower than 0.64 V (vs SHE) on Pt(111). Meantime, the coupling barrier between CO* and OH* is also decreased from 0.47 eV to 0.24 eV. By considering coverage, the individual Rh atom on surface is identified to be more effective than the neighbouring atoms for methanol electrooxidation, and thus a moderate Rh coverage is suggested. This work provides some insight into the binary catalysts for methanol electrooxidation.

The adsorption of citrate anions on Pt{h k l} single crystal electrodes and Pt nanoparticles was investigated using cyclic voltammetry (CV). Citrate is found to behave as a simple, specifically adsorbing anion, stronger in its surface interaction with platinum than either (bi-) sulphate or OH but displaying no tendency to decompose at 293 K into molecular fragments such as chemisorbed carbon monoxide. No preference for a particular adsorption site was exhibited by citrate either, as would be expected from its reported ability to control the shape of growing Pt nanoparticles. Rather, citrate is readily removed from platinum surfaces either by exposure to aqueous sodium hydroxide (it acts as a non-specifically adsorbing anion at high pH) or potential excursions to potentials

NSFC [21073152, 20933004, 20833005, 21021002]; Major State Basic Research Development Program of China [2012CB215500]; Foundation for the Author of National Excellent Doctoral Dissertation of China [201126]; Fundamental Research Funds for the Central Universities [2010121021]; Program for New Century Excellent Talents in University [NECT-11-0301, NECT-10-0715]

Fundamental Research Funds for the Central Universities [2010LKHX03, 2010QNB04, 2010QNB05]; major State Basic Research Development Program of China [2009CB220102]

The coadsorption of CN− and CO on Pt(1 1 0) electrode in acid solutions was investigated by using cyclic voltammetry and in situ FTIR spectroscopy. In comparison with individual adsorption of CO or CN−, the onset oxidation potential of CO (COad) coadsorbed with CN− is positively shifted ca. 100 mV, and its oxidation peak is postponed ca. 260 mV together with a significant decrease in current density. When the coadsorbed CO has been stripped completely, the CV recovers the feature of Pt(1 1 0)/CN− surface, which signifies that the coadsorption of CO does not affect the oxidation behavior of the coadsorbed CN− ( CN ad - ). In comparison of CN− and CO adsorbed alone, the CN ad - band is blue shifted from 2090 to 2108 cm−1 at 0.0 V, and the stark tuning rate is decreased dramatically from 53 to 4 cm−1 V−1; while the COad band is red shifted from 2075 to 2064 cm−1 at 0.0 V, and the stark tuning rate is slightly decreased from 24 to 19 cm−1 V−1, The result revealed the strong interaction between CN ad - and COad at Pt(1 1 0) surface in the coadsorption system.

A novel composite material of SnO2/ordered mesoporous carbon (SnO2/OMC) was prepared through a hydrolysis process. The morphology, structure and composition of the SnO2/OMC was characterized by using powder X-ray diffraction (low-angle and wide-angle diffraction patterns), transmission electron microscopy (TEM), thermogravimetric analysis (TG-DTA) and nitrogen-adsorption measurement. Cyclic voltammetry (CV) and galvanostatic discharge–charge measurements were used to test the electrochemical performance of the SnO2/OMC. It has found that the SnO2/OMC composite could deliver a reversible capacity as high as 395.6 mAh g−1 up to 50 cycles of discharge/charge. The results demonstrated also a good rate capability. When the charge current density was increased gradually from 200 to 1000 mA g−1 and then returned immediately to 200 mA g−1, 75% of the initial capacity at 200 mA g−1 has been recovered. Therefore, the SnO2/OMC is revealed as a promising candidate of anode material for high energy and high power lithium ion batteries (LIBs).

Special Funds for Major State Basic Research Project of China [2009CB220102]; NSFC [20833005, 20773102, 20910088]

In this paper we report the development of an electrochemical in situ rapid-scan time-resolved microscope infrared reflection spectroscopy (RS-TR-MFTIRS), which consists of a FTIR spectrometer with rapid-scan facility, an infrared microscope in combination with a nanostructured Pt microelectrode, and a versatile external reflection (or thin-layer) spectroelectrochemical flow cell. It has been demonstrated that the RS-TR-MFTIRS can successfully overcome the disadvantages in mass transport, transient response and uniformity of current flow that arise from a conventional external reflection infrared cell. The dynamic process of methanol oxidation on a nanostructured platinum microelectrode in alkaline solution was employed as a test reaction to characterize the performance of the newly developed technique. The results illustrate that cyclic voltammograms (CVs) and infrared spectra within a potential interval of 2.6 mV can be simultaneously recorded at a potential scan rate up to 200 mV s −1 . The dynamic processes of the poisoning intermediate (adsorbed CO species) and reactive intermediate (formate ions) involved in methanol oxidation in alkaline solutions were studied intensively. It has been revealed that the bridge-bonded CO (CO B ) species and formate ions are generated preferentially at the onset potential (−0.54 V vs SCE) of methanol oxidation, while the linearly bonded CO (CO L ) species originate at more positive potentials that are close to the anodic current peak potential (−0.17 V vs SCE) of methanol oxidation.

Enhanced IR absorption (EIRA) of CO adsorbed on Pd nanoparticles embedded in the mesoporous molecular sieve SBA-15 was discovered in the current paper. Palladium ions (Pd2+) were introduced into the mesoporous molecular sieve SBA-15 through impregnation of the sieve into palladium chloride solution followed by calcinations. The Pd2+ ions embedded in SBA-15 were reduced firstly to small primary Pd particles (Pd0) by cyclic potential scans between 0.00 and −0.40 V (SCE). Pd nanoparticles (Pd0n) were formed ultimately by adsorption and desorption of CO on Pd0-embedded SBA-15, in which CO served to induce migration and coalescence of the Pd0. Cyclic voltammograms of electrodes of both Pd0 and Pd0n display characteristic features of surface processes of hydrogen adsorption–desorption, which are different from those of a bulk Pd electrode showing mainly bulk processes of hydrogen absorption. Cyclic voltammetric studies demonstrated that electrochemical reactions might be carried out easily in SBA-15 that is composed of an orderly arrangement of hexagonal channels of size 10 nm, ascribed to a small resistance of ion diffusion and electron transition in the Pd0n-embedded SBA-15 system. In situ FTIR results revealed that IR absorption of CO adsorbed on Pd nanoparticles embedded in the SBA-15 has been enhanced 11-fold, and the full-width at half-maximum of the CO bands is significantly increased. Nevertheless, the Stark tuning rate of the IR band of bridge bonded CO is determined to be only 24 cm−1 V−1, which is much smaller than the value (42 cm−1 V−1) measured for the same species on a bulk Pd electrode. The present study is of importance to reveal the particular IR optical properties of metal nanoparticles confined in molecular sieves.

The electrochemical behavior of irreversibly adsorbed antimony on a Pt(110) electrode (Pt(110)/Sb) with various coverages was studied using cyclic voltammetry. The kinetics of HCOOH oxidation via reactive intermediates on Pt(110)/Sb were investigated quantitatively by employing the potential step technique and in situ FTIR spectroscopy. The results demonstrated that Sb adatoms were stable on Pt(110) when the electrode potential was below 0.45 V (SCE). It has been revealed that the dissociative adsorption of formic acid can be inhibited by the presence of Sb ad on the Pt(110) surface. The electrocatalytic effects of Sb ad towards HCOOH oxidation consist in a negative shift of the oxidation potential (about 350 mV) and the enhancement of the oxidation current. Based on the data processing method of integration transform developed in our previous papers, the kinetics of HCOOH oxidation on Pt(110)/Sb electrodes of different θ Sb have been investigated quantitatively, and both the rate constant k f and the transfer coefficient β were determined and reported.

Well-grown 3-D copper clusters were obtained on a Pt(111) surface at intermediate overpotentials from a sulfuric acid solution. The hexagonal and triangular clusters grew layer-by-layer and were aligned to the orientation of the substrate, indicating epitaxial growth without rotation. By using the tip as an anodic electrode, the atomic structure of each layer of the cluster was monitored locally during dissolution. The results show that in the copper clusters the lattice constant relaxes directly to the bulk lattice constant in the second layer (at least after deposition of the third layer). Additional discussion on the dissolution kinetics is also included. The same method has been used to elucidate the structure of the Cu overlayer on Pt(100).

A nanometer-scale thin film of ruthenium supported on glassy carbon (nm-Ru/GC) was prepared by electrochemical deposition under cyclic voltammetric conditions. Scanning tunneling microscopy (STM) was used to investigate the structure and to measure the thickness of the thin film. It has been found that the Ru thin film is composed of layered Ru crystallites that appear in a hexagonal form with dimensions of about 250 nm and thickness around 30 nm. In situ FTIR spectroscopic studies demonstrated that such a nanostructured Ru thin film exhibits abnormal infrared effects (AIREs) for CO adsorption (G.Q. Lu et al., Langmuir 16 (2000) 778). In comparison with CO adsorbed on a massive Pt electrode, the IR absorption of CO ad on nm-Ru/GC was significantly enhanced. Moreover, the direction of CO ad bands is inverted and the full width at half maximum of CO ad bands is increased. It has been revealed that the enhancement factor of IR absorption of CO adsorbed on nm-Ru/GC electrodes depends strongly on the thickness of the Ru film. An asymmetrical volcano relationship between the enhancement factor and the thickness of the Ru film has been obtained. The maximum value of the enhancement factor was measured as 25.5 on a nm-Ru/GC electrode of Ru film thickness around 86 nm. The present study has contributed to exploration of the particular properties of nanostructured Ru film material and to the origin of the abnormal infrared effects.

The kinetics of HCOOH oxidation via a reactive intermediate on Pt(100), Pt(110), Pt(111), Pt(510) and Pt(911) single crystal electrodes were studied quantitatively. The difficulty due to the self-poisoning involved in HCOOH oxidation has been overcome successfully by designing a programmed potential step procedure, which is based on results of kinetic studies of dissociative adsorption of HCOOH. The data processing method of integration transform of j∼t transient data was developed for extracting kinetic parameters. The rate constant (kf), the apparent activation energy (ΔH≠°) and the transfer coefficient (β) for HCOOH oxidation on different Pt single crystal electrodes have been evaluated. The values of ΔH≠° obtained on the 5 Pt single crystal electrodes vary from 10.1±0.1 to 32.7±0.2 kJ mol−1. The results demonstrated that the well-defined Pt(110) electrode possesses the lowest value of ΔH≠° amongst the 5 Pt single crystal electrodes studied, signifying a higher electrocatalytic activity for HCOOH oxidation. According to the values of ΔH≠°, the electrocatalytic activity of the three basal planes of Pt single crystals can be arranged in the ascending order of Pt(110)>Pt(111)>Pt(100). The values of ΔH≠° of the two stepped surface are close to that of Pt(100) (32.2±0.5 kJ mol−1), which is in good accord with the configuration of surface structure of the two stepped surfaces since the majority surface sites are of (100) symmetry. It has been found that the transfer coefficient β does not vary with the reaction temperature, and manifests a similar variation as that of ΔH≠° versus the orientation of the Pt single crystal electrode. The small values of β (ranging from 0.102±0.004 to 0.251±0.008) may suggest a stepwise transfer of two electrons and imply the unavoidable interaction of HCOOH with surfaces of the Pt single crystal electrodes. The variation of ΔH≠° and β versus the orientation of Pt single crystal electrode demonstrated, from a kinetic point of view and for the first time, the effects of surface atomic arrangement towards HCOOH oxidation.

The electropolymerization of ortho -phenylenediamine ( o -PD) in 0.10 M H 2 SO 4 , 0.10 M H 2 SO 4 +0.40 M Na 2 SO 4 , and 0.50 M H 2 SO 4 solutions was studied using an electrochemical quartz crystal microbalance. The poly-( ortho -phenylenediamine) (P o PD) films were formed during continuous potential cycling between −0.40 V and +0.95 V versus SCE. The decrease in the resonant frequency of the quartz crystals during electropolymerization of phenylenediamine demonstrated that the deposition of the polymer films occurred mainly in the potential range where the monomers were anodically oxidized. Dramatic changes in the resonant frequency and the resonant admittance were observed during the redox processes at potentials below +0.20 V. At least two kinds of deposits could be distinguished in the P o PD films. The surface concentration of the electroactive sites of the polymer prepared in 0.10 M H 2 SO 4 and in 0.10 M H 2 SO 4 +0.40 M Na 2 SO 4 solutions were much higher than that prepared in 0.50 M H 2 SO 4 . The acidity of the solution rather than the concentration of the anions of the electrolyte was found to have a strong influence on the electropolymerization processes. The results were discussed in the light of the effects of the solubilities of oligomers in solutions during the electropolymerization processes and the changes in the structures of the initially formed polymer films.

The electrooxidation of 1,3-butanediol (1,3-BD) on platinum electrodes in perchloric and sulphuric acid solutions was studied by using cyclic voltammetry and in situ FTIR spectroscopy. The determination of intermediates and products involved in 1,3-BD oxidation was carried out in solutions prepared using either millipore water or deuterated water as solvent. The in situ FTIRS data acquired from experiments of single potential alteration and time-resolved determination demonstrated that the oxidation of 1,3-BD on the Pt electrode is a complex process and may obey a dual path reaction mechanism. Three pathways were determined in 1,3-BD oxidation. The first one is the dissociative adsorption of 1,3-BD, which yields CH 3 CHOHCH 3 and poison species CO ad . The second one is the dehydration of 1,3-BD, which produces intermediates of CH 3 CHCHCH 2 OH and CH 2 CHCH 2 CH 2 OH. The last one is the direct oxidation of 1,3-BD at potentials above 0.30 V(SCE) on a Pt surface free of CO ad , which produces intermediates of CH 3 CHOHCH 2 COOH and CH 3 COCH 2 CH 2 OH. These intermediates are characterised by IR bands appearing near 2045 (CO ad ), 1600 (>CC −1 (>CO) and a series of IR bands locating in the fingerprint region and around 3000 cm −1 . All the above intermediates can be oxidised further to acid compounds, among them acetoacetic acid which is characterised by the double carbonyl bands at 1724 and 1712 cm −1 and has been determined as the majority species. As the acid compounds can be oxidised to CO 2 which yields IR absorption at 2345 cm −1 via a C–C bond breaking process at relatively high electrode potentials, they have been considered to play the role of both intermediate and product in 1,3-BD oxidation. The ultimate product of 1,3-BD oxidation at potentials above 0.30 V(SCE) is determined as CO 2 . The comparison of IR features of 1,3-BD oxidation with those of 1-butanol oxidation reported in our previous paper [1] illustrated the effects of molecular structure in electrocatalysis of C 4 molecules.

The electrooxidation of 1-butanol (1-BL) on Pt electrodes was studied using cyclic voltammetry and in situ FTIR spectroscopy. The results demonstrated that 1-BL can undergo dehydration to form CH3CH2CH  CH2 in acid solutions. The IR absorption of of the C  C bond yielded a broad band around 1600 cm−1, which has been determined in solutions prepared using both Milli-Q water and deuterated water. Evidence for dissociative adsorption of 1-BL on a Pt surface was given by the appearance of an IR band near 2060 cm−1, which was assigned to IR absorption of linearly bonded CO species. At potentials below 0.30 V(SCE), the dissociative adsorbates accumulated and absorbed stably on the Pt surface to inhibit the oxidation of 1-BL. When the adsorbed CO species started to be removed by oxidation at potentials ≥ 0.30 V(SCE), two strong IR bands near 2345 and 1712 cm−1 appeared in the spectra. The band near 2345 cm−1 was attributed to the asymmetrical stretch of the CO2 molecule which is the product species. The IR band near 1712 cm−1 was ascribed to IR absorption of the carbonyl group, which, together with the IR bands appearing in the fingerprint region, suggested the production of butyric acid in the oxidation of 1-BL. In considering the large intensity of the carbonyl band in spectra obtained at potentials above 0.30 V(SCE), the butyric acid was assigned as one of the product species. Butyric acid has been considered also as an intermediate species involved in 1-BL oxidation, since, at higher potentials (> 0.40 V), butyric acid can be oxidised to CO2, although the complete oxidation of butyric acid to CO2 is rather difficult. The present study demonstrated, at the molecular level, that the oxidation of 1-BL obeys the dual-path reaction mechanism.

The role of the oxidation state of a platinum polycrystalline surface in the electrocatalytic oxidation of C1 to C4 primary alcohols has been studied by using electrochemical techniques, in situ FTIR spectroscopy and X-ray photoelectron spectroscopy. The results revealed that the oxidation state of the Pt surface plays a key role in the oxidation of primary alcohols, and demonstrated that the oxidation of C1 to C4 primary alcohols on a Pt electrode is controlled by the formation of surface oxides on the Pt electrode at different potentials. It was found that the dependence of the reaction process on the oxidation states of the platinum surface yielded similar features in the cyclic voltammogram for oxidation of different primary alcohols at a Pt electrode. According to the effects in the oxidation of primary alcohols, the surface oxides of platinum may be classified as active and poison species. The Pt surface oxides of higher oxidation states (Pt(OH)3 and PtO2) formed at potentials above 1.0 V (SCE) were identified as poison species, while other lower oxidation states of Pt surface oxides such as PtOH, Pt(OH)2 and PtO may be identified as the possible active species for primary alcohol oxidation.

The adsorption of CO on dispersed thin layers of platinum and palladium supported on glassy carbon (Pt/GC and Pd/GC) was studied using in sity multi-step FTIR spectroscopy (MS-FTIRS). Novel properties of the dispersed Pt and Pd thin layers with respect to CO adsorption have been observed for the first time. In comparison to the adsorption of CO on smooth Pt and Pd surfaces, the IR features of CO adsorbed on Pt/GC and Pd/GC electrodes become abnormal, consisting mainly in (1) the direction of the IR band being inverse, (2) the intensity of the IR band being enhanced significantly with an enhancement factor of 20 for linearly bonded CO on Pt/GC and 26 for bridge bonded CO on Pd/GC, and (3) the FWHM of the IR band being broadened by about 6–9 cm−1. The abnormal optic properties of the dispersed Pt and Pd thin layers with respect to CO adsorption were attributed to the particular structure of the thin layers, which is undergoing further investigation.

The kinetics of dissociative adsorption of formaldehyde on Pt(111) electrodes was investigated using a programmed potential step technique and in situ time-resolved Fourier transform IR spectroscopy (TR-FTIRS). We have demonstrated that the products of dissociative adsorption of HCHO on Pt(111) consist of both linear and bridge bonded CO. In contrast, the adsorption of CO from CO saturated solution yields only linearly adsorbed CO species on this electrode. In the potential range between −0.25 and 0.25 V the rate of dissociative adsorption of HCHO on Pt(111) displays a volcano curve with two maxima located at −0.06 and 0.15 V respectively. The reaction rate maintains relatively high values between the two maxima. However, at potentials below −0.06 or above 0.15 V, the rate drops quickly towards zero. The initial rate ν i of the dissociative adsorption of HCHO on Pt(111) was found to be on the order of 10 −11 mol cm −2 s −1 . The TR-FTIRS studies confirmed the dynamic properties of the dissociative adsorption of HCHO on Pt(111) electrodes.

Electrochemistry, Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) have been employed to study the stability of the Au(210) electrode surface in the presence of adsorbed pyridine. The experiments have been performed in an ultrahigh vacuum (UHV)-electrochemistry apparatus that allows for a fast transfer of the sample between an UHV chamber equipped with LEED and AES equipment and an electrochemical chamber in which electrochemical experiments can be performed. The “dry emersion” technique has been employed to emerse the electrode at a controlled potential and to transfer it into the UHV chamber for analysis of its surface composition using AES and its surface structure by LEED. Experiments performed in a weakly adsorbing electrolyte and in 10−3 M pyridine solution have shown that the Au(210) electrode surface displays a remarkable stability at the metal-solution interface. Its surface structure is apparently unchanged when the electrode charge density varies between −30 μC cm−2 and + 30 μC cm−2, both in a pure weakly adsorbing electrolyte and in the presence of the chemisorbed organic molecule.

In the present paper four platinum single crystal electrodes, two basal planes of Pt(111) and Pt(110) and two stepped surfaces of Pt(332) and Pt(331), were prepared and used in the study of electro-oxidation of ethylene glycol (EG). All of these Pt single crystal electrodes belong to the [1 1 0] zone of crystallography, and exhibit on their surface (111) symmetry sites or certain combinations of terraces of (111) symmetry with steps of (111) symmetry type. It has been found that as a result of a favourable steric matching of surface sites the Pt(110) electrode manifested a higher activity both for EG dissociative adsorption and oxidation than that of the Pt(111) electrode. The stepped surfaces of Pt(332) and Pt(331) operated with certain combinations of characteristics of Pt(111) and Pt(110). The best electrocatalytic properties have been obtained with a Pt(331) electrode, and this is attributed both to the configuration of the atomic arrangement and to the stability of this surface. In summary, the above results show that the performance of a given Pt single crystal electrode in EG oxidation at a potential below 1.0 V may be evaluated by three factors. 1. (1) The ability to resist self-poisoning (AB) which describes the difficulty of EG dissociative adsorption on the electrode surface. 2. (2) The activity for EG oxidation (AC). In considering that the threshold potential for EG oxidation on all electrodes is at 0.3 V and that the self-poisoning is encountered in PGPS, the activity for EG oxidation may be reasonably characterized by the intensity of the peak current acquired in NGPS near 0.6 V, which corresponds to the maximum current of EG oxidation on an activated (non-poisoned) surface of the electrode. 3. (3) The stability of activity during potential cycling (SA) between 0.05 and 1.0 V, which describes the resistance to the decrease of intensity of the EG oxidation current during voltammetric cycling. For the two basal planes studied, the AB and SA of Pt(111) are higher than those of Pt(110), but its AC is much lower than that of Pt(110). These differences are clearly related to the surface atomic arrangement of the two electrodes. As has been discussed above, the surface of Pt(111) is atomically smooth and stable during voltammetric cycling. The surface of Pt(110) presents, however, atomic steps and is reconstructed under experimental conditions, i.e. certain steric configurations are encountered on the Pt(110) surface. The high AC and the low AB may be assigned to a favourite stereographic matching during EG adsorption and oxidation on Pt(110). The two electrodes with stepped surfaces, Pt(332) and Pt(331), contain different densities of (110) sites, which are formed on the border between terrace and step, as shown in Fig. 8. The AB of these two electrodes has been observed at a moderate range between that of Pt(111) and the AB of Pt(110). With a majority of (111) sites on its surface, the electrode of Pt(332) operates at a relatively higher AC than Pt(111) does, and its SA is not as good as that of Pt(111) but is much better than the SA of a Pt(110) electrode. In all cases the highest AC and SA are obtained with a Pt(331) electrode. It may be seen from the profile of a (331) plane (shown by the cross-section of A-A in Fig. 8) that all atoms on the top of the surface participated in forming (110) sites, and the atom on the step has two functions — one is to form a (110) site with an atom located in the terrace of second layer and the other is to form a (111) site in the terrace of the same layer. It has been mentioned in the above discussions that the Pt(110) electrode keeps a higher AC due to favourite stereographic matching in EG adsorption and oxidation, but its SA is the worst, due to the instability of the surface. The highest AC and SA obtained with Pt(331) may be ascribed not only to the high density of (110) sites existing on the surface, but also to the stabilization of these (110) sites, and moreover, the synergy generated by the atomic arrangement of the Pt(331) surface may also contribute to the performance of the Pt(331) electrode.