Bimetallic Ni and Pt single atoms anchored on nitrogen–phosphorus doped porous carbon fibers to achieve significant electrocatalytic hydrogen evolution

Abstract

The commercial application of water electrolysis for hydrogen production requires the development of low precious metal catalysts with a high crustal abundance. One feasible strategy is to utilize bimetallic catalysts composed of both transition and precious metals. In this study, a novel N/P-doped Ni/Pt bimetallic catalyst is developed (NiPt@C-NP, 3.68 % Ni, 0.2 % Pt) using polyacrylonitrile fibers as an inexpensive carbon source for catalyst support. Due to strong anchoring from the N and P heteroatoms, the nickel and platinum species are mono-atomically dispersed throughout the catalyst. Under acidic conditions, NiPt@C-NP exhibits a hydrogen evolution overpotential of 89 mV (10 mA cm−2), whereas an unsupported platinum catalyst gives an overpotential of 302 mV. The mass activity of Pt in NiPt@C-NP reaches 36.17 A mgPt−1, which is 33 times higher than 20 % Pt/C (1.07 A mgPt−1). Density functional theory (DFT) calculations reveal that synergistic interactions between Ni and Pt significantly increase the density of state near the Fermi level of NiPt@C-NP, resulting in a reduced bandgap and an enhanced charge transfer capability. Furthermore, the Gibbs free energy at the Pt and Ni sites is − 0.25 and − 0.63 eV, respectively, indicating fast reaction kinetics.