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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 kinetics of dissociative adsorption of HCOOH on Pt(100), Pt(610), Pt(210) and Pt(110) single-crystal electrodes has been investigated. The oxidation of dissociative adsorbate (DA) derived from the dissociative adsorption of HCOOH was used as a probe reaction together with the potential-step technique of short time windows. The quantity Q ad of DA produced at a given potential E ad and in a defined time window t ad of adsorption has been determined systematically. At fixed t ad peaked curves of Q ad versus E ad in the potential range between −0.25 and 0.25 V/SCE have been obtained on all four electrodes. The maximum rate of dissociative adsorption of HCOOH decreases in the order Pt(110) ⪢ Pt(210) ⪢ Pt(610) ⪢ Pt(100).