Triple Functions of Ni(OH)₂ on the Surface of WN Nanowires Remarkably Promoting Electrocatalytic Activity in Full Water Splitting

Abstract

Discovering efficient and promising non-noble catalysts toward the alkaline hydrogen evolution reaction (HER) is vital for a clean energy system. Here, we design an efficient alkaline HER electrocatalyst, coating of WN nanowire core with a Ni­(OH)2 shell supported on a carbon fiber paper (WN-Ni­(OH)2). In a 1 M KOH solution, the hierarchical electrocatalyst affords a current density of 20 mA cm–2 at an overpotential of 170 mV and 100 mA cm–2 at 245 mV. The enhanced performance of WN-Ni­(OH)2 in the HER is attributed to the synergy between WN and Ni­(OH)2: during water dissociation, hydroxyl groups are preferentially adsorbed on WN and hydrogen on Ni­(OH)2; meanwhile, Ni­(OH)2 could promote hydroxyl group desorption from WN. Thus, the full-surface Volmer reaction kinetics could be enhanced. As a consequence, the WN-Ni­(OH)2 has a reduced activation energy of the HER and enhanced intrinsic activity performance. Meanwhile, the hybrid can reach a current density of 100 mA cm–2 at an overpotential of 339 mV for the oxygen evolution reaction (OER), and an overpotential of 510 mV for the full water-splitting reaction. This interfacial cooperation offers a promising bifunctional electrocatalyst, as well as a hopeful strategy for fabricating efficient nitride-based electrocatalysts in alkaline media.

Sequenced Successive Ionic Layer Adsorption and Reaction for Rational Design of Ni(OH)2/FeOOH Heterostructures with Tailored Catalytic Properties

“…In the Ni 2p spectra, Ni 2p 1/2 and Ni 2p 3/2 are detected for both samples. The peak positions of the Ni 2p 1/2 and Ni 2p 3/2 bands appear at 872 and 855 eV, respectively, which is consistent with the divalent nickel pattern and indicates that Ni is present as Ni­(OH) 2 . , The peak position of Fe 2p 3/2 for Ni5­(Fe5/Ni5) 1 (710 eV) is attributable to the intermediate position of the Fe 2+ and Fe 3+ states. , Thus, Fe 2+ remains in the as-deposited film, while partial oxidation to Fe 3+ occurred during the deposition and/or after exposure to air. Thus, the actual chemical composition of the product deviates from FeOOH.…”

Metal nitride-based nanostructures for electrochemical and photocatalytic hydrogen production

“…Tungsten-based nitrides and their combinations with reduced graphene oxide (rGO) [ 219 ], bimetallic nitrides [ 220 ], metal doping [ 221 ], metal carbides [ 222 ], and metal hydroxides [ 223 ] have been extensively used as electrocatalysts for HER. For example, Yan et al demonstrated that even a small amount (2.52 at%) of phosphorus doping can greatly enhance the HER activity of WN/rGO as it significantly alters the electronic state and increases the electron density and the active sites of the material [ 219 ].…”

From Hexagonal to Monoclinic: Engineering Crystalline Phase to Boost the Intrinsic Catalytic Activity of Tungsten Oxides for the Hydrogen Evolution Reaction

“…In consideration of saving energy and protecting the environment, electrocatalysis water splitting is an efficient and clean approach to obtain high-purity hydrogen gas as one of the most potential alternatives for future energy. − As a candidate for Pt-based catalysts, low-cost and high-activity electrocatalysts urgently need to be developed for satisfying the requirement of consuming hydrogen energy in a large scale. , The current research on electrocatalysts for the hydrogen evolution reaction (HER) is mainly focused on the synthesis and modification of non-precious-metal-based compounds such as transition-metal oxides, nitrides, and carbides. − The rational design of catalysts plays a significant role in reducing the activation energy of the reaction to improve the reaction rate and energy conversion efficiency . Based on the Sabatier principle, the hydrogen adsorption energy on catalyst surface should be moderate, too strong to desorb active intermediates, or too weak to activate reactants .…”