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

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 (NiCp2) as a precursor. The Ni nanoparticles are uniformly distributed in the SiCN matrix due to coordination between amine groups of PSSQZ and NiCp2. Hierarchical pore structure provided a path through which H2 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/cm2 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 NiCp2 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.