Cobalt phosphide nanorods as an efficient electrocatalyst for the hydrogen evolution reaction

Abstract

Cobalt phosphide (Co 2 P) nanorods are found to exhibit efficient catalytic activity in hydrogen evolution reaction (HER), with the overpotential required for the current density of 20 mA/cm 2 as small as 167 mV in acidic solution and 171 mV in basic solution. In addition, the Co 2 P nanorods can work stably in both acidic and basic solution during hydrogen production. This performance can be favorably comparable to typical high efficiently non-precious catalysts, and suggest the promising application potential of the Co 2 P nanorods in the field of hydrogen production. The HER process follows a Volmer-Heyrovsky mechanism, and the rates of the discharge step and desorption step appear to be comparable during the HER process. The similarity of charged natures of Co and P in the Co 2 P nanorods to those of the hydride-acceptor and proton-acceptor in high efficient Ni 2 P catalyst, [NiFe] hydrogenase, and its analogues implies that the HER catalytic activity of Co 2 P nanorods might be correlated with the charged natures of Co and P.

Highly branched cobalt phosphide nanostructures for hydrogen-evolution electrocatalysis

“…The overpotentials required to produce a (cathodic) current density of À20 mA cm À2 were À117 mV and À100 mV for the branched nanostructures and multi-faceted nanoparticles, 4 respectively, despite their similar loading densities on analogous Ti substrates. Additionally, the material outperforms previously reported Co 2 P nanostructures (h À20 mA cm À2 ¼ À167 mV), 12 suggesting that the small Co 2 P impurity does not play a 1,4,23 The Tafel slope for the branched CoP nanostructures was 48 mV per decade, which is comparable to the 50 mV per decade Tafel slope observed previously for the multi-faceted pseudo-spherical CoP nanoparticles. 4 The comparable values suggest a similar mechanism for the HER on the branched CoP nanostructures and on the CoP nanoparticles.…”

A Review of Phosphide‐Based Materials for Electrocatalytic Hydrogen Evolution

“…Theoretical studies indicate that the stoichiometry of metal to phosphorus is a key concern to the activity for HER, where positive charged moiety of metal performs as an hydride acceptor while the negative charged moiety of phosphorus acts as a proton acceptor; it is hypothesized that they work cooperatively for delivering molecular H 2 . [ 31,33 ] However, experimental work indicates that phosphides with higher contents of phosphorus would outperform that of lower content. This is manifested in the comparative study of Co 2 P and CoP where on low-index surfaces, more P atoms are exposed in CoP than that of Co 2 P. [ 32 ] Another study of phase-dependent catalytic activity of nickel phosphides, including Ni 12 P 5 , Ni 2 P and Ni 5 P 4 by Pan et al, [ 34 ] also highlights phosphorus and suggests that phosphide with higher P content exhibits higher performance, following the trend Ni 12 P 5 (29%) < Ni 2 P (33%) < Ni 5 P 4 (44%) (Figure 3 e).…”

Tunable and Specific Formation of C@NiCoP Peapods with Enhanced HER Activity and Lithium Storage Performance

“…Specifically,C o-based and Ni-based phosphide compounds with metallic characteristics and good electricalc onductivity have been shown to act as efficient HER catalysts, such as CoP,C o 2 P, Ni 2 P, Ni 12 P 5 ,a nd so on. [6][7][8][9] At the same time, as fossil fuels are being exhausted, the development of high energyd ensity,h igh rate capability,a nd long cycle life energy storage systemsi su rgent to satisfy the need for electricv ehicles (EVs) and hybrid electric vehicles (HEVs). Rechargeable lithium-ion batteries (LIBs), which are regarded as one of the most promising devices, have attractedt remendous adherents in thep ast decades.…”

“…[7,9,14] However,numerousefforts have been devoted to developingm ethods for the preparation of pure-phased Co-and Ni-based phosphide. Co-andN i-based phosphides have showns ome amazingp otential when applied in the fields of catalyst,e nergy storage, magnets, and so on.…”