Three-dimensional tetsubo-like Co(OH)2 nanorods on a macroporous electrically conductive network as an efficient electroactive framework for the hydrogen evolution reaction

Conducting the hydrogen evolution reaction (HER) in an alkaline environment using a non-precious transition metal catalyst with high efficiency is challenging. Here, we report excellent HER activity achieved using three-dimensional (3D) tetsubo-like Co(OH) 2 nanorods on a macroporous electrically conductive network (MECN) synthesized by a hydrothermal method. This unique framework comprises three levels of porous structures, including a bottom-ordered MECN substrate, an intermediate layer of vertically porous Co(OH) 2 nanowires with a mean diameter of 100 nm and length of about 2 μm, and outmost Co(OH) 2 nanosheets ( 20 nm). The 3D array structure with a large aspect ratio provides a large specific surface area and exposes more active sites to catalyze electrochemical reactions at the electrode-electrolyte interface. Compared with Co(OH) 2 nanosheets on an MECN and foamy Co(OH) 2 on an MECN structure, the synthesized architecture has excellent HER catalytic reactivity, including a low potential of −69.2 mV vs. RHE, a cathodic current density of 10 mA cm −2 , a small Tafel slope of 61.9 mV dec −1 , a high current density, and robust catalytic stability in 1 M KOH, and is promising in HER applications. Tetsubo-like Co(OH) 2 nanorods are produced on a macroporous electrically conductive network by a pressurized hydrothermal method and show excellent HER performance.