WEB “In operando” Near Ambient Pressure Photoemission Analysis of Graphene Formation by Methanol Reforming through the Electrochemical Promotion of a Ni CatalystWednesday (23.09.2020) 17:05 - 17:20 F: Functional Materials, Surfaces, and Devices 1 Part of:
In this work we study the reforming reaction of methanol induced by non-Faradaic electrocatalytic promotion catalysis (EPOC) and the resulting low temperature formation of graphene under these conditions (1-3). Using an electrocatalytic cell compatible with a near ambient pressure photoemission (NAPP) spectrometer available in the ALBA Synchrotron (Barcelona, Spain), we follow “in operando” the methanol reforming reaction and demonstrate that multilayer graphene forms by methanol decomposition at 280 °C on an electrochemically promoted nickel catalyst film supported on a K-βAl2O3 solid electrolyte. In operando NAPP spectroscopy and electrochemical measurements, simultaneously taken during the process, have been used to unravel the reaction mechanism rendering graphene and show that polarizing negatively the Ni electrode induces the electrochemical reduction and migration of potassium to the nickel surface. This elemental potassium is responsible of promoting the catalytic decomposition of methanol into graphene and contributes stabilizes the graphene layers formed via diffusion and direct K−C interaction. Experiments reveal that adsorbed methoxy radicals are intermediate species in the reforming reaction process and that, once formed, multilayer graphene remains stable after electrochemical oxidation and back migration of potassium to the solid electrolyte upon positive polarization. The reversible diffusion of ca. 100 equivalent monolayers of potassium through the carbon layers and the unprecedented low-temperature formation of graphene and other carbon forms are mechanistic pathways of high potential impact for applications where mild synthesis and operation conditions are required.
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2.- Espinós, J. P.; Rico, V. J.; González-Cobos, J.; Sánchez-Valencia, J. R.; Pérez-Dieste, V.; Escudero, C.; de Lucas-Consuegra, A.; González-Elipe, A. R. In Situ Monitoring of the Phenomenon of Electrochemical Promotion of Catalysis. J. Catal. 2018, 358, 27−34
3.- Espinós, J. P.; Rico, V. J.; González-Cobos, J.; Sánchez-Valencia, J. R.; Pérez-Dieste, V.; Escudero, C.; de Lucas-Consuegra, A.; González-Elipe, A. R. Graphene Formation Mechanism by the Electrochemical Promotion of a Ni Catalyst. ACS Catal. 2019, 9, 11447-11454