Fabrication of Hierarchically Porous Silicon Carbonitride/Nickel Nanocomposite Using Branch-Structured Polysilazane as a Hydrogen Evolution Reaction Catalyst

Abstract

Hierarchically porous silicon carbonitride/nickel (SiCN/Ni) nanocomposites for a catalyst of the hydrogen evolution reaction (HER) were fabricated using branch-structured polysilazane with phenyl substitution, phenylsilsesquiazane (PSSQZ), and nickelocene (NiCp 2 ) as a precursor. The Ni nanoparticles are uniformly distributed in the SiCN matrix due to coordination between amine groups of PSSQZ and NiCp 2 . Hierarchical pore structure provided a path through which H 2 outgas can diffuse as well as increase active sites where HER can occur due to its large surface area. As a result, the overpotential of 10 mA/cm 2 of the hierarchically porous SiCN/Ni nanocomposite decreased from 540 to 390 mV. In addition, the multiwalled carbon nanotubes (MWCNTs) produced by the catalytic reaction of NiCp 2 lowered the charge transfer resistance to 133 Ω. Furthermore, the fabricated hierarchically porous SiCN/Ni nanocomposite showed stable performance and long-term durability in acidic environments for 100 h because of the high corrosion resistance of the SiCN matrix.