Adsorption and oxidation of hydrocarbons on noble metal electrodes. VIII. Composition of adsorbed methane and rate-limiting step in the overall methane to carbon dioxide reaction

Electro-Oxidation of Methane on Platinum under Ambient Conditions

“…The PEFC performance was the lowest in the case of methane, which is known to have the least reactive C–H bonds of these alkanes . To gain mechanistic insight into the activation and adsorption processes for methane and other hydrocarbons on platinum electrodes, the system was studied under “potentiodynamic” conditions, in which the electrode potential was first held for an extended period of time to activate methane, followed by linear sweep voltammetry to more positive electrode potentials to strip adsorbed intermediates from the catalyst surface. − It was found that during the electrode potential hold, methane is activated and forms C1 species on the electrode surface, which may be partially oxygenated. However, specific speculation into the reaction mechanism could not be performed on the basis of electrochemical experiments alone.…”

Determining the potential-dependent identity of methane adsorbates at Pt electrodes using EC-MS

“…The electrochemical behaviour of methane has been of interest since the 1960s, when early investigations of hydrocarbon fuel cells were conducted using platinum electrodes. 9,10,[17][18][19][20][21][22] Voltammetric studies found that in acidic electrolytes, methane is electrochemically adsorbed at mild potentials as C 1 species, which can be oxidized during an anodic potential sweep. [22][23][24] Based on similarities to the stripping curves of model compounds, methane was suggested to form a partially oxidized intermediate.…”

“…9,10,[17][18][19][20][21][22] Voltammetric studies found that in acidic electrolytes, methane is electrochemically adsorbed at mild potentials as C 1 species, which can be oxidized during an anodic potential sweep. [22][23][24] Based on similarities to the stripping curves of model compounds, methane was suggested to form a partially oxidized intermediate. 20 Early voltammetric studies refer to this species as "reduced CO 2 " that may 25,26 or may not 22,27 correspond to *CO, with *C-OH and *CHO proposed as likely alternatives.…”

“…[22][23][24] Based on similarities to the stripping curves of model compounds, methane was suggested to form a partially oxidized intermediate. 20 Early voltammetric studies refer to this species as "reduced CO 2 " that may 25,26 or may not 22,27 correspond to *CO, with *C-OH and *CHO proposed as likely alternatives. 22 However, interpretation of voltammetric measurements relies on assumptions about the identity of surface adsorbates.…”

Electroadsorptive removal of impurities from perchloric, sulfuric, and phosphoric acids, and sodium hydroxide

“…Long time preelectrolysis has been routinely recommended (1-12) to remove electroactive impurities. Also, physicochemical techniques, such as distillation (13- 15), recrystallization (16,17), oxidation with hydrogen peroxide (18, 19) and adsorption on activated charcoal, platinized platinum, or silica gel (11,12,(20)(21)(22)(23) have often preceded, or followed, preelectrolysis to remove non-electroac-tive impurities. Purification of activated charcoal is tedious and time consuming.…”