Non-Precious Bimetallic CoCr Nanostructures Entrapped in Bamboo-Like Nitrogen-Doped Graphene Tube As a Robust Bifunctional Electrocatalyst for Total Water Splitting

Developing an efficient and cost-effective electrocatalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is of paramount importance for designing metal–air batteries and water electrolyzers. Herein, we present an economical approach for the synthesis of a bifunctional electrocatalyst consisting of cobalt–chromium nanostructures entrapped in a graphene tube doped with nitrogen (CoCr@NGT). The graphene tube is of a large size (cross-sectional diameter ∼ 100 nm) with a wall thickness of more than 10 graphene layers. The Cr alloying with the entrapped Co in the NGT drastically enhanced both the HER and OER performance with a low overpotential (η) and better current density along with long-term durability. Hence, CoCr@NGT can be used as a total alkaline water electrolyzer as both an anode and cathode catalyst delivering a current density of 10 mA/cm 2 at around 1.58 V for a long period of time competing with the state-of-the-art combination of Pt−C and RuO 2 . The electrochemical performance strongly depends on the Cr due to its corrosion resistance capability and improved catalytic sites, which leads to long-term stability and very high activity, respectively.