(6a) Ethanol Oxidation Model for Pt2/Ru2/Sn

King-Ki Fung and Daniela S. Mainardi*

*Institute for Micromanufacturing, Chemical Engineering Program, Louisiana Tech University, Ruston, La 71272

Securing a permanent form of energy is a global concern for mankind. Currently, we rely on energy requirements which are dependent on a finite supply of fossil fuels. This energy supply cannot sustain our energy needs indefinitely. Additionally, combustion engines have brought about environmental harm that is just now being realized. In response to these issues, a necessity for a clean and renewable energy source is desired. In the past decade, solar energy, geothermal energy, wind energy, and fusion power technologies have been explored as an alternative energy supply. Among these, fuel cells have been nominated as a solution to this crisis. Fuel cells take advantages of combustion engine’s continuous operation, as long as fuel is supplied, and batteries’ conversion of chemical energy to electrical. However, they lack the energy output of traditional combustion engines.

There are multiple issues that prevent the commercialization of fuel cells. Among these issue is the sluggish reaction rates partially due to the catalyst. Platinum (Pt) is the typical catalyst of choice, but is expensive and susceptible to CO poisoning.¹ Therefore, new catalysts are being investigated that alloy Pt with another metal. Addition of ruthenium (Ru) to Pt has been shown to promote oxidation of CO to CO2 and thereby decreasing poisoning of active sites across the catalyst.² Another well studied addition to Pt is tin (Sn). Addition of Sn to Pt leads to the dissociative adsorption of ethanol and lead to the weakening of the Pt-CO bond which further promotes ethanol oxidation.³ Formation of a ternary catalyst with Pt/Ru/Sn should lead to the a constructive effect for ethanol oxidation.

            In this work, a novel ternary catalyst, Pt₂/Ru₂/Sn, is investigated for ethanol oxidation. The crystal structure is determined using Material Studios 4.4’s DMOL 3 module with a GGA PW91functional and a DND 3.5 basis set. Using the determined structure, an ethanol oxidation mechanism is proposed based on Density Function Theory (DFT) and molecular dynamic calculations using Material Studios 4.4’s CASTEP module. With the rate data calculated in CASTEP, a dynamic monte carlo simulation is performed with CARLOS 4.0 to observe the real time evolution of chemical reactions which can be compared with experimental data.

References:

1. Vigier, F et al. Electrocatalysis for the Direct Alcohol Fuel Cell, Topics in Catalysis. 40, 111-117 (2006).
2. Datta, J., Singh, S., and Bradyopadhyay. A Comprehensive Study on the Effect of Ru Addition to Pt electrodes for Direct Ethanol Fuel Cells, Bulletin of Material Science. 32, 643-652 (2009).
3. Vigier, F et al. Development of Anode Catalyst for a Direct Ethanol Fuel Cell, Journal of Applied Electrochemistry. 34, 439-446 (2004).