Ultrathin Metal–Organic Framework Nanosheets-Derived Yolk–Shell Ni _0.85 Se@NC with Rich Se-Vacancies for Enhanced Water Electrolysis

Abstract

Selecting ultrathin MOF nanosheets as pre-assembling platforms, yolk-shell structured few-layer N-doped carbon (NC) shell encapsulated Ni 0.85 Se core (denoted as Ni 0.85 Se@NC) via an oriented phase modulation (OPM) strategy are controllably fabricated. The ultrathin nature of MOF nanosheets give rise to the modification of structure at the electronic level with abundant Se-vacancies and effective electronic coupling via the Ni-N x coordination at the interface between the Ni 0.85 Se core and NC shell. The obtained Ni 0.85 Se@NC exhibits low overpotentials for both oxygen evolution reaction (OER) (300 mV) and hydrogen evolution reaction (HER) (157 mV) at 10 mA•cm-2 in alkaline condition, outperforming the corresponding bulk MOFderived counterparts. Through exploiting Ni 0.85 Se@NC as anode and cathode catalysts, a low cell voltage of 1.61 V is achieved to perform alkaline water electrolysis. Remarkably, it also achieves high activity in natural seawater (pH = 7.98) and simulated seawater (pH = 7.86) electrolytes, even surpassing integrated Pt/C-RuO 2 /CC electrodes. Density functional theory (DFT) studies illustrate that abundant Se-vacancies effectively regulate the electronic structure of Ni 0.85 Se@NC by accelerating electron transfer from Ni to N atoms at the interface, and thus make the Ni 0.85 Se@NC a near-optimal electronic configuration to stimulate ideal adsorption free energy toward key reaction intermediates.

Developments and Perspectives on Robust Nano‐ and Microstructured Binder‐Free Electrodes for Bifunctional Water Electrolysis and Beyond

“…An additional benefit is that, compared with conventional water electrolysis, seawater electrolysis technology can be used for both H 2 generation and desalination of seawater. [ 456,457 ] Several other binder‐free electrocatalysts such as yolk–shell Ni–Se, [ 458 ] NiFe–LDH, [ 459 ] and heterogeneous bimetallic phosphide of Ni 2 P–Fe 2 P [ 460 ] have evolved as possible alternatives for energetic seawater electrolysis.…”

Progress and Perspectives of Hollow Multishelled Structures

“…The thickness of MOF coating is tuned by controlling the number of repeated cycles. In addition, through posttreatment, MOF could be converted to carbon, [ 59‐61 ] single atom, [ 62 ] etc . For example, the SnO 2 @MIL‐100(Fe) HoMS is converted to SnO 2 @FeO x ‐C (MOF)‐HoMS and SnO 2 @Fe 2 O 3 (MOF)‐HoMS after post‐annealing‐ treatment first in N 2 protection and then in air (Figures 5b—d).…”

Diradicals or Zwitterions: The Chemical States of m -Benzoquinone and Structural Variation after Storage of Li Ions

“…In another word, the EPR signals in the 4,6DA1,3BQ powders probably came from the trace impurities, diradical states or crystal defects and reconfirmed that the major chemical states of 4,6DA1,3BQ was in the zwitterion form. 39,41,42,47 The electrochemical performance: the effect of intermolecular interactions Encouraged by the prominent stability of 4,6DA1,3BQ due to the resonance structures and the abundant intermolecular interactions, the electrochemical performance of such m-benzoquinone structure was further explored. Meanwhile, the chemical states of 4,6DA1,3BQ could be further confirmed by analysing the active sites and the structural variation after accepting/losing electrons during the redox reactions in batteries.…”