  Based on the random phase approximation calculation in two-orbital honeycomb
lattice model, we investigate the pairing symmetry of Ni-based transition-metal
trichalcogenides by electron doping access to type-II van Hove singularities
(vHs). We find that chiral even-parity d+id-wave (Eg) state is suppressed by
odd-parity p+ip-wave (Eu) state when electron doping approaches the type-II
vHs. The type-II vHs peak in density of states (DOS) enables to strengthen the
ferromagnetic fluctuation, which is responsible for triplet pairing. The
competition between antiferromagnetic and ferromagnetic fluctuation results in
pairing phase transition from singlet to triplet pairing. The Ni-based
transition-metal trichalcogenides provide a promising platform to
unconventional superconductor emerging from electronic DOS.
