So-Called “Metal-Free” Oxygen Reduction at Graphene Nanoribbons is in fact Metal Driven

Catalytic hydrogen evolution reaction on "metal-free" graphene: key role of metallic impurities

Molecular hydrogen is widely considered as a potential carbon-free and renewable energy carrier for a sustainable energy strategy. The electrocatalytic hydrogen evolution reaction is a major pathway to obtain ultra-pure hydrogen, and it vastly relies on the development of inexpensive electrocatalysts. In recent years, graphene has been proposed as a "metal-free" catalyst for the hydrogen evolution reaction. Here, we showed that metallic impurities are introduced during the synthesis process and these impurities act as the catalyst for the hydrogen evolution reaction.

Graphene and its electrochemistry - an update

The electrochemistry of graphene and its derivatives has been extensively researched in recent years. In the aspect of graphene preparation methods, the efficiencies of the top-down electrochemical exfoliation of graphite, the electrochemical reduction of graphene oxide and the electrochemical delamination of CVD grown graphene, are currently on par with conventional procedures. Electrochemical analysis of graphene oxide has revealed an unexpected inherent redox activity with, in some cases, an astonishing chemical reversibility. Furthermore, graphene modified with p-block elements has shown impressive electrocatalytic performances in processes which have been historically dominated by metal-based catalysts. Further progress has also been achieved in the practical usage of graphene in sensing and biosensing applications. This review is an update of our previous article in Chem. Soc. Rev. 2010, 39, 4146-4157, with special focus on the developments over the past two years.

Electrochemical Fluorographane: Hybrid Electrocatalysis of Biomarkers, Hydrogen Evolution, and Oxygen Reduction

Fluorographane (C1 Hx F1-x+δ )n is a new member of the graphene family that exhibits hydrophobicity and a large band gap that is tunable based on the level of fluorination. Herein, sensing and energy applications of fluorographane are reported. The results reveal that the carbon-to-fluoride ratio of fluorographane has a great impact on the electrochemical performance of the materials. Lowered oxidation potentials for ascorbic and uric acids, in addition to a catalytic effect for hydroquinone and dopamine redox processes, are obtained with a high fluoride content. Moreover, fluorographane, together with residual copper- and nickel-based doping, acted as a hybrid electrocatalyst to promote hydrogen evolution and oxygen reduction reactions with considerably lower onset potentials than those of graphane (starting material), which makes this a promising material for a broad range of applications.