Synergistic Coupling of Ni Nanoparticles with Ni₃C Nanosheets for Highly Efficient Overall Water Splitting

Abstract

Exploring earth‐abundant bifunctional electrocatalysts with high efficiency for water electrolysis is extremely demanding and challenging. Herein, density functional theory (DFT) predictions reveal that coupling Ni with Ni3C can not only facilitate the oxygen evolution reaction (OER) kinetics, but also optimize the hydrogen adsorption and water adsorption energies. Experimentally, a facile strategy is designed to in situ fabricate Ni3C nanosheets on carbon cloth (CC), and simultaneously couple with Ni nanoparticles, resulting in the formation of an integrated heterostructure catalyst (Ni–Ni3C/CC). Benefiting from the superior intrinsic activity as well as the abundant active sites, the Ni–Ni3C/CC electrode demonstrates excellent bifunctional electrocatalytic activities toward the OER and hydrogen evolution reaction (HER), which are superior to all the documented Ni3C‐based electrocatalysts in alkaline electrolytes. Specifically, the Ni–Ni3C/CC catalyst exhibits the low overpotentials of only 299 mV at the current density of 20 mA cm−2 for the OER and 98 mV at 10 mA cm−2 for the HER in 1 m KOH. Furthermore, the bifunctional Ni–Ni3C/CC catalyst can propel water electrolysis with excellent activity and nearly 100% faradic efficiency. This work highlights an easy approach for designing and constructing advanced nickel carbide‐based catalysts with high activity based on the theoretical predictions.

Recent Advances in Transition Metal Carbide Electrocatalysts for Oxygen Evolution Reaction

“…For instance, Ouyang et al [33] found out that oxygen was favorable to Co sites adjacent to β-Mo 2 C, because the doping of β-Mo 2 C created a heterointerface and thus effectively lowered the energy barrier. In addition, the research of Wang et al [34] suggests the similar conclusion. Their study revealed that Ni-Ni 3 C exhibited smaller Gibbs free energy change (1.815 eV) for the RDS than Ni (3.877 eV) and Ni 3 C (3.701 eV), indicating the important role of Ni 3 C, which efficiently accelerating kinetic process, thus deceasing the overpotential.…”

“…Note that in the above reactions, chemical groups such as O, OH, and OOH, are absorbed on the active sites (*) of catalysts, including physical or chemical absorption with no radicals involved as many literatures reported [31][32][33][34][35][36]. Generally, the formation of intermediates O* (Equation 15) and OOH* (Equation (16)) has been considered as RDS for OER, and previous literature has reported that TMCs are of great value to decrease overpotential for OER as it usefully accelerates RDS in kinetic process [32].…”

Recent advances in non-precious group metal-based catalysts for water electrolysis and beyond

“…Recently, Mu et al fabricated Ni-Ni 3 C heterostructures to adjust the adsorption of H*. 76 The Ni-Ni 3 C/CC catalyst exhibited a low η 10 of 98 mV in a 1 M KOH electrolyte. Chen et al reported N, B co-doped Co 3 C spheres for multifunctional electrocatalysis.…”

Boosting Hydrogen Evolution on MoS2/CNT Modified by Poly(sodium‐p–styrene sulfonate) via Proton Concentration in Acid Solution

“…However, the sluggish kinetics and large overpotential of HER will reduce the reaction efficiency and increase energy consumption. [1,2] So far, Pt, Ru, Ir and other noble-mental-based electrocatalysts are considered as the most active HER electrocatalysts. However, their high cost and natural rarity restrict their large-scale industrial applications.…”

“…Electrocatalytic hydrogen evolution reaction (HER) is one of the most potential methods for efficiently producing molecular hydrogen without any carbon dioxide emissions. However, the sluggish kinetics and large overpotential of HER will reduce the reaction efficiency and increase energy consumption [1,2] . So far, Pt, Ru, Ir and other noble‐mental‐based electrocatalysts are considered as the most active HER electrocatalysts.…”