The Research Of Methanol Oxidation Reaction Mechanism On Ru(0001) Surface

Direct methanol fuel cell has a broad application prospects, such as in the field of mobile power. Choice of a suitable catalyst to improve the conversion efficiency is the key to the development of methanol fuel cells. In this paper, we use the quantum chemical calculations to study the catalytic metal catalysts for methanol oxidation reaction, giving a clear mechanism of the decomposition reaction of methanol to provide theoretical guidance for the design of direct methanol fuel cell anode catalyst.First, we systematically studied the methanol oxidation reaction on surface Ru(0001) by the use of self-consistent periodic density functional theory(DFT). In the study of most stable adsorption of intermediates, we consider two paths: CO path and non-CO path. Through the optimization of possible intermediate calculations required to find the reaction transition state, we finally confirm the most likely mechanism of the reaction: CH2 O â†' CHO â†' CO â†' COOH â†' CO2(CO path) and CH2 O â†' CH2 OOH â†' HCOOH â†' COOH â†' CO2(non-CO path). By the comparison of CO and non- CO path, we found that the methanol reaction in Ru(0001) surface mainly through non-CO path. The results show, however, before generating CO2, methanol tends to produce more CO, and the CO elimination need to overcome the energy barrier of 1.74 eV and the electrochemical potential of 0.74 V. The reason for this phenomenon is the strong interaction between CO and OH and the weak interactions with the surface. Therefore, we predict that there may be present deposition of CO on Ru(0001) surface, resulting in poisoning of the catalyst. In addition, using microkinetic modeling, the intermediates of CO and H are found in the highest coverage. Increasing the temperature and decreasing the pressure, the coverage of CO will decrease, which suggests that CO poisoning of ease.Secondly, we make a study of methanol surface adsorption and cleavage on Pt/Ru(0001), learning about the mechanism of methanol. For the initial activation of methanol, methanol alone adsorbed as the initial state and the intermediate coadsorption as the final state individual, the results show that the O-H activation energy is minimum, resulting methoxy, namely methanol initial bond breaking way: CH3 OH â†' CH3 O + H; This paper further to study methyl decomposition on Pt/Ru(0001) surface : CH3 O â†' CH2 O â†' CHO â†' CO. By calculating for each step of the reaction energy barrier, we obtain the potential energy surface of methanol decomposition on Pt/Ru(0001) surface. The energy barrier of C-H bond activation in CH3 O decomposition is found higher than the energy barrier on the Ru(0001) surface, indicating that the Pt atom on the surface does not play a catalytic role for its activation; CH2 O decomposition in the C-H bond activation has a low energy barrier comparing with the activation energy barrier on Ru(0001) surface, indicating that in this activation process Pt atoms on the surface plays a catalytic role for the C-H activation; the energy barrier of CHO decomposition in the C-H bond activation is similar to pure Pt surface energy barrier, indicating that the Pt/Ru(0001) surface and the Pt surface is similar in this activation process.