Superb Alkaline Hydrogen Evolution and Simultaneous Electricity Generation by Pt‐Decorated Ni3N Nanosheets

Abstract

The development of efficient hydrogen evolution reaction electrocatalysts is critical to the realization of clean hydrogen fuel production, while the sluggish kinetics of the Volmer‐step substantially restricts the catalyst performances in alkali electrolyzers, even for noble metal catalysts such as Pt. Here, a Pt‐decorated Ni3N nanosheet electrocatalyst is developed to achieve a top performance of hydrogen evolution in alkaline conditions. Possessing a high metallic conductivity and an atomic‐thin semiconducting hydroxide surface, the Ni3N nanosheets serve as not only an efficient electron pathway without the hindrance of Schottky barriers, but also provide abundant active sites for water dissociation and generation of hydrogen intermediates, which are further adsorbed on the Pt surface to recombine to H2. The Pt‐decorated Ni3N nanosheet catalyst exhibits a hydrogen evolution current density of 200 mA cm−2 at an overpotential of 160 mV versus reversible hydrogen electrode, a Tafel slope of ≈36.5 mV dec−1, and excellent stability of 82.5% current retention after 24 h of operation. Moreover, a hybrid cell consisting of a Pt‐decorated Ni3N nanosheet cathode and a Li‐metal anode is assembled to achieve simultaneous hydrogen evolution and electricity generation, exhibiting >60 h long‐term hydrogen evolution reaction stability and an output voltage ranging from 1.3 to 2.2 V.