Ultrafine NiO Nanosheets Stabilized by TiO₂ from Monolayer NiTi-LDH Precursors: An Active Water Oxidation Electrocatalyst

Abstract

Faceted NiO nanoparticles preferentially exposing high surface energy planes demand attention due to their excellent electrocatalytic properties. However, the activity of faceted NiO nanoparticles generally remains suboptimal due to their large lateral size and thickness, which severely limits the availability of coordinatively unsaturated active reactive edge and corner sites. Here, ultrafine NiO nanosheets with a platelet size of ∼4.0 nm and thickness (∼1.1 nm) stabilized by TiO2 were successfully prepared by calcination of a monolayer layered double hydroxide precursor. The ultrafine NiO nanosheets displayed outstanding performance in electrochemical water oxidation due to a high proportion of reactive NiO {110} facets, intrinsic Ni(3+) and Ti(3+) sites, and abundant interfaces, which act synergistically to promote H2O adsorption and facilitate charge-transfer.

Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

“…The existence of vacancies would strikingly change the local chemical and electronic environment of the atoms in materials, which is reflected as obvious XAFS spectral change. The XAFS has been generically used to detect various vacancies including metal and nonmetal in the nanocatalysts . Zhang and co‐workers have synthesized an ultrathin δ‐MnO 2 nanosheets electrocatalyst (≈1.4 nm, denoted as NS‐MnO 2 ) with abundant oxygen vacancies for overall water splitting .…”

Recent Progress on Layered Double Hydroxides and Their Derivatives for Electrocatalytic Water Splitting

“…Currently, transition‐metal (Fe, Co, Ni, Mn, and Mo)‐based catalysts including metal oxides,23, 24, 25, 26, 27, 28, 29, 30 hydroxides,31, 32, 33, 34, 35 phosphides,36, 37, 38, 39, 40, 41, 42 sulfides,43, 44, 45, 46, 47, 48 selenides,49, 50, 51, 52, 53, 54 and nitrides55, 56, 57, 58, 59, 60, 61, 62 have been highlighted as the most promising candidates of OER and HER electrocatalysts. Especially, layered double hydroxides (LDHs)63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85 and their derivatives (metal hydroxides, oxyhydroxides, oxides, bimetal nitrides, phosphides, sulfides, and selenides)86, 87, 88, 89, 90, 91, 92…”

A highly-efficient oxygen evolution electrode based on defective nickel-iron layered double hydroxide

“…Instead, 3d-transition metals (Ni, Co, Fe, etc.) have received increasing research interest owing to the earth abundance and considerable activity [14][15][16][17][18][19]. Notably, NiFe-based catalyst has shown the highest activity among the 3d-transition metal systems in alkaline conditions.…”