Methanol oxidation on Ru(0001) for direct methanol fuel cells: analysis of the competitive reaction mechanism

Abstract

Competitive oxidation of CH3OH to CH2O occur via CH3OH → CH3O → CH2O vs. CH3OH → CH2OH → CH2O, further to COOH by the OH group via CH2O → CHO → CO + OH → COOH vs. CH2O + OH → CH2OOH → CHOOH → COOH, and finally oxidation to CO2 on Ru(0001).

An insight into methanol oxidation mechanisms on RuO2(100) under an aqueous environment by DFT calculations

“…The dehydrogenation mechanism on RuO 2 (100) differs from that on metal surfaces following a step-wise dehydrogenation mechanism resulting in inevitable CO formation. 18,[20][21][22][23][24] On the RuO 2 surface, an indirect C-H bond breaking mechanism is suggested that the O-H bond breaking can effectively lower the C-H bond breaking barriers. On the OH* covered palladium surface, a concerted-like mechanism has been reported that the C-H bond breaking can induce the O-H bond breaking in ethanol, implying an inherent relationship between the C-H and O-H bonds.…”

“…[11][12][13][14][15] Wang et al also found that RuO 2 (100) was more active than Ru(0001) in CO oxidation. 16 In comparison with the most stable RuO 2 (110) surface, [17][18][19] the RuO 2 (100) with the higher surface energy was less investigated in the literature.…”

“…Some studies have been carried out theoretically towards the establishment of reaction mechanisms for methanol oxidation and a lot of surfaces have been studied by first principles calculations. [18][19][20][21][22][23][24] Results obtained at the gas/solid interfaces are not very convincing, since behaviors of interfacial water are crucial towards understanding the electrocatalysis chemistry. From the simulations performed in an aqueous interfacial model with explicit water molecules, we may learn a great deal about electrocatalysis at the atomic scale than without them.…”

Mechanisms of CO Activation, Surface Oxygen Removal, Surface Carbon Hydrogenation, and C–C Coupling on the Stepped Fe(710) Surface from Computation

“…Since it is very hard to prove the formation of surface CH x on the perfect Fe(110) surface experimentally and theoretically, the more opened surfaces, such as stepped and kinked surfaces, should be taken into consideration. Computationally CO dissociation on the Ru(0001) surface is found more difficult than CO hydrogenation to CHO 10 and the subsequent CH x O hydrogenation to CH x+1 O is more favored than CH x O dissociation into CH x + O kinetically and thermodynamically, and consequently, CO consecutive hydrogenation tends to form methanol rather than surface CH x (x = 0, 1, 2, 3, 4). The same results are found on the Co(0001) surface, 11 where the methanol route is optimal, while CH x O dissociation into CH x as well as CH x coupling with CO are not favored kinetically and thermodynamically.…”

Methanol Decomposition on Co(0001): Influence of the Cobalt Oxidation State on Reactivity

“…Conversely, O–H bond activation is more competitive than C–H bond activation on the surface of Ni(111) . In addition, CH 3 OH decomposition starts with O–H bond scission to produce CO and H 2 and has also been found on the Ru(0001), , Fe(110), and Ir(111) , surfaces, whereas a small amount of C–O bond scission product was also observed on the Ru(0001), Fe(110), and Ir(111) surfaces.…”