Engineering a Local Free Water Enriched Microenvironment for Surpassing Platinum Hydrogen Evolution Activity

Abstract

Manipulating the catalyst–electrolyte interface to push reactants into the inner Helmholtz plane (IHP) is highly desirable for efficient electrocatalysts, however, it has rarely been implemented due to the elusive electrochemical IHP and inherent inert catalyst surface. Here, we propose the introduction of local force fields by the surface hydroxyl group to engineer the electrochemical microenvironment and enhance alkaline hydrogen evolution activity. Taking a hydroxyl group immobilized Ni/Ni3C heterostructure as a prototype, we reveal that the local hydrogen bond induced by the surface hydroxyl group drags 4‐coordinated hydrogen‐bonded H2O molecules across the IHP to become free H2O and thus continuously supply reactants forcatalytic sites catalytic sites. In addition, the hydroxyl group coupled with the Ni/Ni3C heterostructure further lowers the water dissociation energy by polarization effects. As a direct outcome, hydroxyl‐rich catalysts surpass Pt/C activity at high current density (500 mA cm−2 @ ≈276 mV) in alkaline medium.

Rational construction of loosely packed nickel nanoparticulates with residual HCOO ligands derived from a Ni-MOF for high-efficiency electrocatalytic overall water splitting

“…During the post-treatment process, in addition to the interaction of metal ions, some residues of organic ligands or the components in organic ligands can get inserted on the surface of their derivatives, thereby enhancing the catalytic performance. As reported by Wen et al , 42 the stable surface –OH on the Ni/Ni 3 C heterostructure was retained by a one-step transformation from Ni-MOF nanosheets, which exhibited excellent catalytic performance toward the HER in alkaline medium ( η 500 ≈ 276 mV). In addition, according to the DFT calculations, the hydroxyl group coupled with the Ni/Ni 3 C heterostructure further lowered the water dissociation energy by polarization effects.…”

Promoting water dissociation for efficient solar driven CO2 electroreduction via improving hydroxyl adsorption

“…The detailed investigation of the reaction mechanism will be discussed later. Next, electrochemical impendence spectroscopy (EIS) was carried out and fitted by equivalent circuit to investigate the electrochemical interface properties 51 , 52 . With the introduction of V O , the charge transfer can be accelerated, which is beneficial for conductivity and reducing the overpotential (Supplementary Fig.…”

Thermal Shrinkage Engineering Enables Electrocatalysts for Stable Hydrogen Evolution at 2000 mA cm−2

“…[ 53 ] This result indicates that there is a stronger potential‐determined charge‐transfer rate in Ru‐Ni(OH) 2 ‐200, revealing its overwhelming reaction kinetics under more negative potential compared to Pt/C. [ 54 ] The analogous tendency can be analyzed in the phase peak values at various potentials in the Bode phase diagram (Figure 5d), suggesting the lower Faradic resistance and faster surface reaction rate with the increase of potential in Ru‐Ni(OH) 2 ‐200 than those in Pt/C. All of the above analyses confirm that more absorbed water/hydrogen is available to Ru‐Ni(OH) 2 ‐200 to ensure the equilibrium between adsorption and consumption rate.…”