Nanostructured Nickel Phosphide as an Electrocatalyst for the Hydrogen Evolution Reaction

Abstract

Nanoparticles of nickel phosphide (Ni2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange membrane-based electrolysis is operational. The catalytically active Ni2P nanoparticles were hollow and faceted to expose a high density of the Ni2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.

Nanostructured hydrotreating catalysts for electrochemical hydrogen evolution

“…The adsorption free energy of hydrogen on the Ni 2 P (001) surface has also been calculated by DFT to be 0.31 eV 19 and recently a turn over frequency (TOF) of 0.015 s -1 was estimated at  = 100 mV for an active Ni 2 P HER electrocatalyst. 20 The measured TOF is equivalent to an exchange current density of j 0 = 7.2x10 -6 A cm -2 , assuming an active site density of 1.5x10 15 site cm -2 . The activity of an electrocatalyst is often expressed as a given current density at a given overpotential.…”

“…Notably, they predicted that an ensemble effect favours HER by reducing the number of Ni active sites, thereby decreasing the energy cost for hydrogen removal from Ni 2 P. Recently, Popczun et al reported that nanostructured nickel phosphides are indeed an active electrocatalyst for HER in acidic solutions. 20 They synthesized uniformly distributed and multifaceted nanoparticles of Ni 2 P which have an average grain size of 17 nm (Fig. 13a).…”

One‐Dimensional Earth‐Abundant Nanomaterials for Water‐Splitting Electrocatalysts

“…The effect of different morphologies on their catalytic activities has also been studied for a variety of earth‐abundant HER electrocatalysts, such as MoS 2 ,41, 42, 43 amorphous MoS 2 ,44 WS 2 ,45, 46 Ni 2 P,47 CoP48 and Ni‐Mo alloys 49, 50. In 2014, Jin and coworkers reported the synthesis of metallic cobalt pyrite (cobalt disulfide, CoS 2 ) with different morphologies including films, microwires and nanowires, and showed their capabilities as a high‐activity candidate for HER 27.…”

Nickel Hydr(oxy)oxide Nanoparticles on Metallic MoS2 Nanosheets: A Synergistic Electrocatalyst for Hydrogen Evolution Reaction

“…A variety of earth‐abundant materials including transition metal chalcogenides,14, 15, 16, 17, 18 phosphides,19, 20, 21, 22 carbides,23, 24 metal oxides,25 and metals or their alloys26, 27, 28, 29 have been identified as potential candidates. However, a large part of these electrocatalysts only exhibit noticeable activities and stabilities in acidic electrolytes but suffer from either low activity or instability in alkaline media 30, 31, 32. In general, HER in alkaline media shows lower kinetics and higher sensitivity to the catalyst surface structure than in acidic media 4, 8.…”