Insights and Activation Energy Surface of the Dehydrogenation of C₂H_xO Species in Ethanol Oxidation Reaction on Ir(100)

Abstract

Dehydrogenation of an organic compound is the first and the most fundamental elementary reaction in many organic reactions. In ethanol oxidation reaction (EOR) to form CO 2 , there are a total of 46 pathways in C 2 H x O (x = 1-6) species leading to the removal of all six hydrogen atoms in five CÀ H bonds and one OÀ H bond. To investigate the degree of dehydrogenation in EOR under operando conditions, we performed density function theory (DFT) calculations to study 28 dehydrogenation steps of C 2 H x O on Ir(100). An activation energy surface was then constructed and compared with that of the CÀ C bond cleavages to understand the importance of the degree of dehydrogenation in EOR. The results show that there are likely 28 dehydrogenations in EOR under fuel cell temperatures and the last two hydrogens in C 2 H 2 O are less likely cleaved. On the other hand, deep dehydrogenation including 45 dehydrogenations can occur under ethanol steam reforming conditions.

Activity Enhancement of PtIr Catalysts for Complete Ethanol Oxidation Reaction by Tuning C–O Coupling Abilities

“… a The unit of energies is in eV. b Full reaction species are listed in Table S1. H in product is omitted; b- and h- represent bridge-site and hollow-site adsorbed species. c Data for another type of transition state is shown in Table S4. d Data taken from ref . e Data taken from ref . f Data taken from ref . …”

“…Unlike the catalytic oxygen reduction, 10−12 there are 46 dehydrogenation reactions and 24 possible C−C bond cleavages of C 2 H x O species in anode catalysis. 13 These 70 reactions exclude the potential reactions of C−O or C−OH decoupling of C 2 H x O species. Furthermore, the EOR network has to include the less studied oxidations of C 1 species to form CO 2 as well as water dissociation, which are largely lacking studies, but will be demonstrated in this work as critical for the design of EOR catalysts.…”

“…One of the challenges in EOR catalysis research is the involvement of many elementary reactions in the reaction network. Unlike the catalytic oxygen reduction, − there are 46 dehydrogenation reactions and 24 possible C–C bond cleavages of C 2 H x O species in anode catalysis . These 70 reactions exclude the potential reactions of C–O or C–OH decoupling of C 2 H x O species.…”

“…Therefore, a complete EOR comprises three overlapping stages of reactions: dehydrogenation of C 2 H x O species ( x = 1–6), C–C bond cleavage of C 2 H x O, and water dissociation and the conversion of C 1 intermediates into CO 2 . The most investigated critical factors in achieving a complete EOR are the reactions leading to the C–C bond cleavage and the acetic acid formation, while the most investigated catalysts consist of Pt , and Ir , followed by Pd and Cu. − Additionally, Rh, Ni, and Co were used for ethanol reforming. , …”

Osmotic pressure induced toxicity by aggregation of citrate-coated silver nanoparticles inside HepG2 cells

“…Silver nanoparticle (AgNP) is one of the emerging and fastest growing materials in the field of nanotechnology [1][2][3] and Biomedicine [4][5][6][7][8] that benefited from the advancements in the studies of nanoparticles [9][10][11][12][13][14] and applications such as in catalysis [15][16][17][18][19][20][21][22][23][24][25][26][27][28] . The rapid growth of Agbased nanomaterials is attributed to silver's antimicrobial properties [29][30][31][32][33][34][35] , good optical, conductive, and other outstanding properties [36][37][38][39] .…”