A bifunctional catalyst of ultrathin cobalt selenide nanosheets for plastic-electroreforming-assisted green hydrogen generation

Despite the tremendous advances of electrocatalysts for the hydrogen and oxygen evolution reactions (HER/OER), there are few reports on bifunctional catalysts for the HER and plastic electroreforming. Herein, we present a facile hydrothermal and selenization treatment to fabricate cobalt selenide nanosheets on nickel foam (0.1-CoSe 2 /NF) as a bifunctional catalyst for plastic-electroreforming assisted water electrolysis. Benefiting from its large specific surface area, abundant active sites, high conductivity and 3D porous structure, 0.1-CoSe 2 /NF exhibits superior electrocatalytic performance and durability for both the HER and electrooxidation of plastic waste polylactic acid (PLA). Overpotentials of 202 mV (cathodic) and 288 mV (anodic) are observed at a current density of 100 mA cm −2 in an alkaline electrolyte. Moreover, PLA oxidation that suppresses the OER also addresses the safety concern of gas crossover in water electrolysis. Our work thus provides a promising pathway for low-cost, high efficiency, and stable production of green hydrogen assisted by electroreforming of plastic waste. Cobalt selenide nanosheets with 3.5 nm thickness can be used as a bifunctional electrocatalyst for plastic-electroreforming-assisted water electrolysis, achieving a current density of 10 mA cm −2 at a voltage of only 1.37 V in 1 M KOH with 1 mM PLA electrolyte.