Simple synthesis of a CoO nanoparticle-decorated nitrogen-doped carbon catalyst from spent coffee grounds for alkaline hydrogen evolution

초록

Non-precious metallic electrocatalysts are attracting attention for use in the hydrogen evolution reaction (HER) because they are inexpensive, highly efficient, and durable. Notably, carbon-based catalysts, such as transition metal and heteroatomic-doped carbon materials, are promising candidates to replace precious metal catalysts. The functionalization of the carbon matrix with nitrogen and cobalt is an effective way to develop the electrocatalytic properties of carbon-based catalysts. However, simple and cheaper synthesis methods for catalysts have not been fully investigated. Herein, we report on a cobalt oxide nanoparticle-decorated nitrogen (N)-doped carbon catalyst synthesized by a simple two-step method using spent coffee grounds (SCG). In the first step, SCG-derived carbon (SCG-KU) was obtained by pyrolysis under high temperatures with urea and potassium hydroxide. Second, SCG-KU was functionalized with urea and cobalt chloride. We determined that Co@SCG-KU had a high Brunauer-Emmett-Teller (BET) surface area (1413.2 m(2) g(-1)); cobalt nanoparticles were uniformly distributed in hierarchically porous carbon and surrounded by graphitic carbon. Electrochemical performance results confirmed that the Co@SCG-KU possessed a high electrocatalytic effect (0.28 V at 10 mA cm(-2)) and better HER stability (at 5.0 mA cm(-2) for 8 h). Our results demonstrate a simple, eco-friendly, and low-cost method to prepare a more efficient carbon-based electrocatalyst from SCG in hydrogen evolution applications.

키워드