Porous single-crystal Ni5P4 nanosheets arrays coated with PANI layer for high efficiency hydrogen evolution at high current density in acid electrolyte

Abstract

In acidic electrolyte solution, due to the presence of large amounts of H+, under the premise of ensuring stability, the catalyst in the acidic electrolyte usually has higher HER performance than in alkaline electrolyte. Unfortunately, most metal-based electrocatalysts, are unstable in acidic electrolytes, especially in high-current density working scenarios. Thus, the development of catalysts with high stability at high current density in acidic electrolytes is the key for large-scale hydrogen production. In this study, 3D single crystal porous Ni5P4 nanosheet arrays slightly coated with polyaniline (PANI@Ni5P4/CC) was constructed on the carbon cloth. The PANI@Ni5P4/CC catalyst showed excellent HER catalytic performance at high current density in acidic electrolytes. At 10 mA/cm2 in 0.5 M H2SO4 electrolyte (pH=1), although the HER overpotential of PANI@Ni5P4/CC (77 mV) was higher than that of the 20% Pt/C cayalyst (35 mV), when the current density reached 100 mA/cm2, the HER overpotential of the PANI@Ni5P4/CC electrode was 294 mV, much lower than that of the 20% Pt/C electrode (462 mV). This benefited from the good acid resistance of the single-crystal structure of the Ni5P4 core and the protection of the PANI shell. Moreover, the porous Ni5P4 structure facilitated the escape of the gas, which further improved the HER performance of the PANI@Ni5P4/CC catalyst.