Atomic and electronic modulation of self-supported nickel-vanadium layered double hydroxide to accelerate water splitting kinetics

Abstract

Herein, ruthenium (Ru) and iridium (Ir) are introduced to tailor the atomic and electronic structure of self-supported nickel-vanadium (NiV) layered double hydroxide to accelerate water splitting kinetics, and the origin of high hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities are analyzed at atomic level. X-ray photoelectron spectroscopy and X-ray absorption near-edge structure spectroscopy studies reveal synergistic electronic interactions among Ni, V, and Ru (Ir) cations. Raman spectra and Fourier and wavelet transform analyses of the extended X-ray absorption fine structure indicate modulated local coordination environments around the Ni and V cations, and the existence of V vacancies. The Debye–Waller factor suggests a severely distorted octahedral V environment caused by the incorporation of Ru and Ir. Theoretical calculations further confirm that Ru or Ir doping could optimize the adsorption energy of intermediates in the Volmer and Heyrovsky steps for HER and accelerate the whole kinetic process for OER.

Etching‐Doping Sedimentation Equilibrium Strategy: Accelerating Kinetics on Hollow Rh‐Doped CoFe‐Layered Double Hydroxides for Water Splitting

“…On the other hand, as a common way of modifying the intrinsic activity of the electrocatalysts, the introduction of heteroatoms can generate vacancies or change the electronic structure of the active species. [22][23][24][25] Therefore, it was widely applied to develop bifunctional LDH electrocatalysts. [24,25] Nevertheless, with the solving of the poor intrinsic activity, another problem arises, namely, the number of active sites might be limited by morphology features from general protocols.…”

Nanoheterostructures of Partially Oxidized RuNi Alloy as Bifunctional Electrocatalysts for Overall Water Splitting

“…The RuNi‐30//RuNi‐30 couple displays a cell voltage of 1.42 V at the current density of 10 mA cm −2 (Figure i), which is much lower than that of the RuO 2 //Pt/C couple (1.52 V). Compared with reported values, 1.42 V is also the lowest (see Tables S3–S5 for a summary of recently reported results). More importantly, this low voltage is achieved by a bifunctional catalyst for both the HER and OER, produced by a facile approach without employing toxic chemical agents.…”

“…Transition metal nitrides, sulfides, phosphides, and hydroxides and their composites have been designed for the electrocatalytic water splitting. Although the cell voltage of overall water splitting has been continually lowered, few catalysts can achieve a voltage lower than 1.45 V at a current density of 10 mA cm −2 .…”

“…In recent years, many efforts have been made to improve OER activity, such as morphology engineering to expose more active sites and element doping to modify the electronic structure . Several reported systems, based on layered double hydroxides and transition metal chalcogenides, have demonstrated overall cell voltages below 1.45 V.…”

Specific “Unlocking” of a Nanozyme‐Based Butterfly Effect To Break the Evolutionary Fitness of Chaotic Tumors

“…However, we observed a clear lattice and diffraction patterns assigned to IrO 2 in high‐resolution TEM images and selected‐area electron diffraction (SAED) patterns (Figure d), thus suggesting the successful preparation of IrO x . The deconvolution of the X‐ray photoelectron spectroscopy (XPS) spectrum of IrO x in the Ir 4f region shows two binding peaks at about 61.8 and 64.8 eV and peaks at 62.4 and 65.6 eV corresponding to Ir 4+ and Ir 3+ , respectively (Figure e), while deconvoluted peaks at about 530.3 and 531.6 eV in the O 1s region suggest the existence of iridium oxide and hydroxide (Figure f), respectively, as further confirmed by the broad absorption around 3322 cm −1 in the FTIR spectrum (see Figure S4). The IrO x NPs have a negative charge (ζ potential: ca.…”