Nanometric Ni₅P₄ Clusters Nested on NiCo₂O₄ for Efficient Hydrogen Production via Alkaline Water Electrolysis

Abstract

A number of non‐noble catalysts are developed for hydrogen production via acidic water electrolysis. Nevertheless, for the more economical alkaline hydrogen generation, the restricted kinetics of the water dissociation Volmer step along with its following proton recombination Tafel step for these non‐noble electrocatalysts generally lead to sluggish hydrogen‐production process. Here, a facile method is designed to nest nanometric Ni5P4 clusters on NiCo2O4 (achieving Ni5P4@NiCo2O4) by a phosphating process of NiO clusters on NiCo2O4. Acting as a high‐efficiency electrode for alkaline water electrolysis, the Ni5P4@NiCo2O4 can efficiently and preferentially convert H2O to H2 with a low overpotential of 27 mV at 10 mA cm−2 and the Tafel slope of 27 mV dec−1, which are comparable to the results for platinum and superior than those of the state‐of‐the‐art platinum‐free electrocatalysts. Density functional theory calculations confirm that NiCo2O4 species exhibit a higher ability to electrolyze water into H* intermediate and then Ni5P4 clusters facilitate the subsequent desorption of the H2 products. Profiting from the promoted kinetic steps, the Ni5P4@NiCo2O4 electrocatalyst is promising for scalable alkaline hydrogen production.

Metal Nanoclusters: New Paradigm in Catalysis for Water Splitting, Solar and Chemical Energy Conversion

“…(5) in the next section] due to a maximum density of states on the 5d orbital of the Pt atom. In another recent report, Ni 2 P 5 NCs were deposited on NiCo 2 O 5 for HER and was found superior to the state‐of‐the‐art Pt/C catalyst . An extremely small overpotential (15 mV) and a Tafel slope of 27 mV dec −1 was calculated for the HER in 1 m KOH.…”

“…In another recent report, Ni 2 P 5 NCs were deposited on NiCo 2 O 5 for HER and was found superiort ot he state-of-the-artP t/C catalyst. [192] An extremely small overpotential (15 mV) and aT afel slope of 27 mV dec À1 was calculatedf or the HER in 1 m KOH. Based on mechanistic studies, it was found that this hybrid materialh as ag reat potential to facilitateb otht he Volmer and Ta fel steps [Eq.…”

Metal‐Organic Precursor–Derived Mesoporous Carbon Spheres with Homogeneously Distributed Molybdenum Carbide/Nitride Nanoparticles for Efficient Hydrogen Evolution in Alkaline Media

“…For practical applications, a water electrolysis device requires to operate the oxygen evolution reaction (OER) and HER in the same medium . However, most of the reported OER catalysts work efficiently just in alkaline condition, which shows that conventional HER catalysts are technologically and commercially limited due to lack of efficient and affordable counter electrodes .…”

Engineering 2D Metal–Organic Framework/MoS2 Interface for Enhanced Alkaline Hydrogen Evolution

“…However, in alkaline solutions, H* is formed by the dissociation of water, which may introduce an additional energy barrier and very likely becomes the rate‐determining step . Thus, both water dissociation and hydrogen adsorption should be carefully considered when designing highly efficient electrocatalysts for alkaline HER . As mentioned before, MoS 2 possesses near‐optimal hydrogen adsorption, which is highly desirable for acidic HER .…”