Compositional and crystallographic design of Ni-Co phosphide heterointerfaced nanowires for high-rate, stable hydrogen generation at industry-relevant electrolysis current densities

Lack of high-performance noble-metal free electrocatalysts for hydrogen evolution reaction (HER) to exceed the benchmark Pt-based electrocatalysts, still remains a major hurdle on the way to clean hydrogen economy. Here we rationally, atomistically design and synthesize the hetero-interfaced Ni-Co phosphide nanowires which deliver exceptional activity and stability in water electrolysis under industry-relevant current densities. The compositional and crystallographic design produces extra-stable Ni5P4-Co2P nanowires sprouting from a Ni-Co alloy foam (NCF). The extraordinary reactivity is ensured by the heterointerfaces between the highly-active (303) crystal planes of Co2P and Ni5P4 nanowire phases. The overpotentials of Ni5P4-Co2P/NCF catalysts at-10,-100, and-1000 mA cm(-2) are about 21, 92 and 267 mV in 1 M KOH, respectively, far exceeding the commercial Pt/C catalysts. The Tafel slope of Ni5P4-Co2P/NCF catalyst is only 23 mV dec(-1) , indicating an even faster HER kinetic compared to Pt/C (32 mV dec(-1)). Moreover, the Ni5P4-Co2P/NCF catalyst shows an ultra stable and lasting performance, evidenced by only a minor 3.6% drop at j250 after 100 h continuing operation. The DFT calculations confirm that the exposed heterointerfaces between (303) planes of Ni5P4 and Co2P phases play a key role for boosting the HER activity of Ni5P4-Co2P electrocatalyst.

Automated summary

This study presents the rational design and synthesis of hetero-interfaced Ni-Co phosphide nanowires, which exhibit exceptional activity and stability in water electrolysis under industry-relevant current densities. The Ni5P4-Co2P/NCF catalysts show significantly lower overpotentials and faster reaction kinetics compared to commercial Pt/C catalysts.