One-step hydrothermal synthesis of honeycomb 3D graphene-like Co9S8 and its catalytic characteristics for NaHCO3 reduction by H2S

•Honeycomb 3D graphene-like Co9S8 catalyst was synthesized via a simple route.•NaHCO3 plays a critical role for the formation of honeycomb Co9S8.•NaHCO3 was reduced to formic acid as high as 3680 mg/L.•The prepared Co9S8 acts as a catalyst in the process of NaHCO3 reduction.

Honeycomb 3D graphene-like Co9S8 nanocrystallines were successfully synthesized using cobalt and Na2S·9H2O as starting materials without a template via a simple hydrothermal route. The composition, structure, morphology, and catalytic activity of the as-prepared Co9S8 were characterized by investigation of XRD, SEM, EDS, XPS, GC–MS and HPLC. It was found that an appropriate concentration of inexpensive NaHCO3 play a critical role for the formation of honeycomb Co9S8 nanocrystallines. On the other hand, Co9S8 acted as a catalyst in the hydrothermal reaction, producing formic acid reduced from NaHCO3 as high as 3680 mg/L. It indicates that the present study not only proposes a simple way of honeycomb Co9S8 synthesis, but also provides a potential approach to CO2 reduction.

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