Operando X-ray and Mass Spectroscopy of Reduced Graphene Oxide ( rGO )-Mediated Cobalt Catalysts for Boosting the Hydrogen Evolution Reaction

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Inserting underlying reduced graphene oxide ( rGO ) into Co aims to regulate the chemical integrity and catalytic ability of the Co upper layer for hydrogen evolution reaction (HER) as a green-hydrogen goal. Principally, an mass spectrometer indicates 3.8 times more considerable hydrogen generation in Co / rGO than in Co . The spectroscopical approaches, combining soft and hard X-ray probing, illustrate the chemical oxidation evolution of electronic Co -3 and Co -4 states differently regarding the underlying rGO contribution. A unique examination is regarded as the phase transition from the initial middle to high oxidation and to deoxidation, related to the intermediate Co 0 existence and H 2 generation. The chemical adsorption of Co – O ( H ) , Co – H ads , and H 2 molecules desorption have been assigned their spectral significances. The rGO mediation indicates two significant metal Co and Co – O ( H ) blocks in the two-dimensional - domain. Density-functional-theory (DFT) calculation provides the regeneration, sustained stability, and decreasing energy barrier of Co – H ads catalysts due to the rGO incorporation, thereby augmenting the HER enhancement through the alternative Volmer-Heyrovsky process. The experiment, including mass spectrometer, soft, and hard X-ray, provides evidence regarding the catalyst’s HER enhancement. This study offers insights into the chemical composition, electronic structure, and active role of Co bonded with or without the extinct OH and H bonds, advancing our comprehension of electrocatalytic reactions, thus taking our knowledge of composite materials to stepwise electrocatalytic reactions forward. This cutting-edge experiment under environment and DFT studies gives critical information regarding the catalytic mechanism and chemical stability of the Co and rGO materials. Published by the American Physical Society 2024

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