Fast and Facile Room-Temperature Synthesis of MOF-Derived Co Nanoparticle/Nitrogen-Doped Porous Graphene in Air Atmosphere for Overall Water Splitting

Generally, metal-organic framework (MOF)-derived electrocatalysts are prepared by thermal pyrolysis at high temperatures of around 600-900 degrees C and in inert atmosphere. Herein we introduce a laser-induced method for preparation of MOF-derived Co nanoparticle/nitrogen-doped porous graphene (Co/PNG) at room temperature and in air atmosphere. Through a laser scribing method, the organic complex is converted into nitrogen-doped graphene (PNG) and meanwhile the decomposition of the organic linker yields a reductive chemical atmosphere. This reductive atmosphere and high energy at the local position of laser irradiation allows the reduction of Co ions into atomic Co species and in turn enables the formation of Co/PNG. In addition, the flexible polyimide (PI) film-supported Co/PNG could be directly used as an electrode for electrocatalysis without the requirement of any binder. The electrocatalytic activity of the obtained electrode could be easily controlled by adjusting the power or the loading of MOFs. The electrocatalytic result indicates that Co/PNG shows satisfying activity and stability for water electrolysis. With the porous properties and Co-N-x active sites, the flexible electrode shows overpotentials of 131, 335, and 380 mV for hydrogen, oxygen evolution reaction, and overall water splitting reaction.