EMIRS STUDIES OF FORMIC-ACID ELECTROOXIDATION ON PD, AU AND PD + AU ALLOYS .1. INVESTIGATION OF THE ADSORBATES DERIVED FROM HCOOH AND NACOOH CHEMISORPTION AT PD IN ACID AND ALKALINE-SOLUTIONS

An electromodulated IR reflectance spectroscopy (EMIRS) study of the adsorbed species resulting from HCOOH and NaCOOH chemisorption at a smooth Pd electrode is presented. In acid solution, large amounts of multibonded CO species are detected, in contrast with the absence of any type of CO adsorbate in alkaline solutions. For the latter, the appearance of adsorbed formate species can be concluded from the increase in the intensity of two bands at 1060 and 2960 cm-1. These results suggest that the adsorbate is bound to Pd via two O atoms. In acid solution, however, the contribution of a formate species bound to the metal through a single O atom is discussed as the result of competitive adsorption with the multibonded CO species.