Vertically aligned Ni/NiO nanocomposites with abundant oxygen deficient hetero-interfaces for enhanced overall water splitting

TY - JOUR

T1 - Vertically aligned Ni/NiO nanocomposites with abundant oxygen deficient hetero-interfaces for enhanced overall water splitting

AU - Wang, Hongxia

AU - Cui, Meiyan

AU - Fu, Gaoliang

AU - Zhang, Jiaye

AU - Ding, Xingyu

AU - Azaceta, Irene

AU - Bugnet, Matthew

AU - Kepaptsoglou, Demie M.

AU - Lazarov, Vlado K.

AU - de la Peña O’Shea, Victor A.

AU - Oropeza, Freddy E.

AU - Zhang, Kelvin H.L.

N1 - Funding Information: Kelvin H.L. Zhang is grateful for funding support by the National Natural Science Foundation of China (21872116). F.E. Oropeza and V. A. de la Peña O’Shea are grateful for the funding supported by the EU (ERC CoG HyMAP 648319) and Spanish AEI (NyMPhA PID2019-106315RB-I00). Also, this work has been funded by the regional government of Comunidad de Madrid and European Structural Funds through their financial support to FotoArt-CM project (S2018/NMT-4367). Besides, Fundación Ramon Areces funded this work though ArtLeaf project. Kelvin H.L. Zhang also acknowledge the Sino-German Mobility Program (M-0377). SuperSTEM is the National Research Facility for Advanced Electron Microscopy, funded from the Engineering and Physics Research Council (EPSRC). M. Bugnet is grateful to the SuperSTEM Laboratory for microscope access, and to the School of Chemical and Process Engineering at the University of Leeds for a visiting associate professorship and financial support. Publisher Copyright: © 2022, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.

PY - 2022/7/11

Y1 - 2022/7/11

N2 - The design of heterostructured transition metal-based electrocatalysts with controlled composition and interfaces is key to increasing the efficiency of the water electrolysis and the elucidation of reaction mechanisms. In this work, we report the synthesis of well-controlled vertically aligned Ni/NiO nanocomposites consisting of Ni nanoclusters embedded in NiO, which result in highly efficient electrocatalysts for overall water splitting. We show that such a high catalytic efficiency toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) originates from a synergetic effect at Ni/NiO interfaces that significantly reduces the energy barrier for water dissociation, and favours the formation of reactive H* intermediates on the Ni side of the interface, and OHads on the NiO side of the interface. A study of water chemisorption based on near-ambient pressure photoelectron spectroscopy indicates that the abundant hetero-interfaces in Ni/NiO nanocomposite promote the dissociation of water with a three-fold increase in the surface concentration of OHads compared with pure NiO. Density functional theory calculations indicate that Ni/NiO interface leads to the reduction of the water dissociation energy barrier due to a high concentration of oxygen vacancies at NiO side of the interface, whereas the formation of highly active metallic Ni sites with an optimal value of Gibbs free energy of H* (ΔGH* = −0.16 eV) owes to a favourable adjustment of the electron energetics at the interface, thus accelerating the overall electrochemical water splitting.

AB - The design of heterostructured transition metal-based electrocatalysts with controlled composition and interfaces is key to increasing the efficiency of the water electrolysis and the elucidation of reaction mechanisms. In this work, we report the synthesis of well-controlled vertically aligned Ni/NiO nanocomposites consisting of Ni nanoclusters embedded in NiO, which result in highly efficient electrocatalysts for overall water splitting. We show that such a high catalytic efficiency toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) originates from a synergetic effect at Ni/NiO interfaces that significantly reduces the energy barrier for water dissociation, and favours the formation of reactive H* intermediates on the Ni side of the interface, and OHads on the NiO side of the interface. A study of water chemisorption based on near-ambient pressure photoelectron spectroscopy indicates that the abundant hetero-interfaces in Ni/NiO nanocomposite promote the dissociation of water with a three-fold increase in the surface concentration of OHads compared with pure NiO. Density functional theory calculations indicate that Ni/NiO interface leads to the reduction of the water dissociation energy barrier due to a high concentration of oxygen vacancies at NiO side of the interface, whereas the formation of highly active metallic Ni sites with an optimal value of Gibbs free energy of H* (ΔGH* = −0.16 eV) owes to a favourable adjustment of the electron energetics at the interface, thus accelerating the overall electrochemical water splitting.

KW - electronic structure

KW - heterostructure

KW - hydrogen evolution reaction

KW - vertically aligned nanocomposites

KW - water splitting

UR - http://www.scopus.com/inward/record.url?scp=85138354127&partnerID=8YFLogxK

U2 - 10.1007/s11426-022-1326-2

DO - 10.1007/s11426-022-1326-2

M3 - Article

SN - 1674-7291

JO - Science China Chemistry

JF - Science China Chemistry

ER -