Methanol adsorption on PtCo(111): A DFT Study

ORAZI, VALERIA; BECHTHOLD, P.; E. GONZÁLEZ; JASEN, PAULA; JUAN, ALFREDO

Dalian

Congreso; 2nd International Conference on Applied Surface Science; 2017

Fuel cells (FCs) are attractive sources of electrical power since the production of electrical energy can be maintained aslong as the reactants are supplied to the electrodes. In addition, FC technology is a favorable energy source for a myriadof reasons. It presents low environmental impact, high electric conversion efficiency for different systems (35?70%),independence of size, reliability and long lasting operation, production of heat that is usable for co-generation cycles, andthe flexibility of the utilized fuel. Also, the FCs offer a cleaner and more efficient source of energy when compared withother energy-conversion devices. Among all kinds of FCs, direct methanol fuel cells (DMFC) have really exhibitedpotentialities to replace current portable power sources and micro power sources in the market, like lithium-ion batteries.The performance of DMFCs is limited due to the presence of various drawbacks, including kinetics constraints andcatalyst poisoning. Methanol oxidation is a slow reaction that requires active sites for the adsorption of the molecule. Theuse of methanol (CH 3 OH) as fuel presents several advantages in comparison to hydrogen: it is a cheap liquid fuel, easilyhandled, transported, and stored; with a high theoretical energy density. The methanol adsorption, and its decompositionproducts, on transition metal surfaces has been extensively investigated, one example involves platinum surfaces and Pt-modified metals. Pt is the most active metal; however, the poor abundance and high cost limit commercial applications.One solution is the alloying of Pt with cheaper 3-d metals, such as Fe, Co, and Ni. In this sense, the Pt-Co alloy has beenused for multiple purposes, because of its interesting magnetic and catalytic behavior, it is more tolerant to CO poisoning,and the methanol electrooxidation reaction starts at less positive potentials than bare-Pt. The Co improve the methanoloxidation reaction (MOR) of the electrocatalyst due to the lowering of the electronic binding energy, which promotes theC?H cleavage reaction at low potentials.