Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

• Published in: Journal of the Serbian Chemical Society 2005-01, Vol.70 (2), p.231-242
• Main Authors: Desic, Maja, Popovic, Milica, Obradovic, Maja, Vracar, Ljiljana, Grgur, Branimir
• Format: Article
• Language: English
• Subjects: gold; hydrogen evolution; modified electrodes; oxygen reduction; platinum
• ISSN: 0352-5139; 1820-7421
• DOI: 10.2298/JSC0502231D

Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal-chloride complexes using cyclic voltammeter. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER) and oxygen reduction (ORR) reactions. Aplatinum overlayer on a gold substrate increases the activity for HER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum. Povrsinska modifikacija platine zlatom i zlata platinom je izvrsena iz rastvora sumporne kiseline i odgovarajucih hloridnih kompleksa metala primenom ciklicne voltametrije. Poredjenjem kolicine naelektrisanja u oblasti potpotencijalne depozicije vodonika i odgovarajucih oblasti redukcije oskida cistih i modifikovanih elektroda zakljuceno je da platina na zlatu formira 3D, a zlato na platini 2D ostrva. Aktivnosti ovako modifikovanih povrsina za reakcije izdvajanja vodonika i redukcije kiseonika u rastvoru sumporne kiseline poredjene sa aktivnostima cistih metala. Elektroda od zlata modifikovana platinom znacajno uvecava aktivnost za obe ispitivane rekacije u poredjenju sa cistim zlatom. Sa druge strane, elektroda od platine modifikovana zlatom ima neznatno manju aktivnost u poredjenju sa cistom platinom. Zbog ogranicenih resursa i visoke cene platine platina modifikovana zlatom moze biti zamena za cistu platinu kao dobar katalizator za reakciju redukcije kiseonika, posebno u gorivim spregovima u oblasti niskih temperatura.