Molecular Functionalization of NiO Nanocatalyst for Enhanced Water Oxidation by Electronic Structure Engineering

Abstract

Tuning the local environment of nanomaterial-based catalysts has emerged as an effective approach to optimize their oxygen evolution reaction (OER) performance, yet the controlled electronic modulation around surface active sites remains a great challenge. Herein, directed electronic modulation of NiO nanoparticles was achieved by simple surface molecular modification with small organic molecules. By adjusting the electronic properties of modifying molecules, the local electronic structure was rationally tailored and a close electronic structure-activity relationship was discovered: the increasing electron-withdrawing modification readily decreased the electron density around surface Ni sites, accelerating the reaction kinetics and improving OER activity, and vice versa. Detailed investigation by operando Raman spectroelectrochemistry revealed that the electron-withdrawing modification facilitates the charge-transfer kinetics, stimulates the catalyst reconstruction, and promotes abundant high-valent γ-NiOOH reactive species generation. The NiOÀ C 6 F 5 catalyst, with the optimized electronic environment, exhibited superior performance towards water oxidation. This work provides a well-designed and effective approach for heterogeneous catalyst fabrication under the molecular level.

Dual Active Center-Assembled Cu31S16–Co9-xNixS8 Heterodimers: Coherent Interface Engineering Induces Multihole Accumulation for Light-Enhanced Electrocatalytic Oxygen Evolution

“…At the initial stage, the peaks below 400 cm –1 and the strong character peak at 680 cm –1 ( A 1g models) can be assigned to Co 7.2 Ni 1.8 S 8 , which kept the same phase of Co 9 S 8 . , The weak peak at 479 cm –1 corresponds to the S–S stretching bond in Cu 1.94 S . When the applied potential increases to 1.2 V, the two peaks at 448 and 484 cm –1 gradually show up, which can be attributed to the A 1g stretching modes of Ni–OH and Ni–O, respectively . It indicates that the slight part of the heterodimer surface begins to evolve into amorphous Ni­(OH) 2 , accompanied by the blue shift of the peak (676 cm –1 ) of Co 7.2 Ni 1.8 S 8 .…”

“…46,47 The weak peak at 479 cm −1 corresponds to the S−S stretching bond in Cu 1.94 S. 48 When the applied potential increases to 1.2 V, the two peaks at 448 and 484 cm −1 gradually show up, which can be attributed to the A 1g stretching modes of Ni−OH and Ni−O, respectively. 49 It indicates that the slight part of the heterodimer surface begins to evolve into amorphous Ni(OH) 2 , 50 accompanied by the blue shift of the peak (676 cm −1 ) of Co 7.2 Ni 1.8 S 8 . As the potential is raised to 1.3 V, the point at which the OER occurs, new features of the typically amorphous Co(OH) 2 appear at 481, 518, 611, and 679 cm −1 .…”

Enhanced Storage and Interface Structure Stability of NCM811 Cathodes for Lithium‐Ion Batteries by Hydrophobic Fluoroalkylsilanes Modification

“…A similar phenomenon was also observed in a previous report. [ 35 ] Fluoroalkylsilane modification can effectively anchor Ni cations on the surface of NCM811 cathode material and then inhibit the dissolution of TMs, especially Ni cations. Moreover, after fluoroalkylsilane modification, the affinity between cathode particles and electrolyte decreases (supported by contact angle test), which inhibits TM dissolution.…”

Surface‐Functionalized Nanoparticles as Catalysts for Artificial Photosynthesis

“…The postfunctionalization of ultrasmall (1–3 nm) NiO NPs with small organic molecules (MeOPh─, HCO 2 Ph─, Cl 2 Ph─, NO 2 Ph─, and C 6 F 5 ─) results on those bearing electron‐withdrawing substituents (i.e., C 6 F 5 ─) as the most active (both in terms of overpotentials and current densities, see Table 1, entries 3–8) in OER. [ 79 ] A combined electrochemical (CV, bulk electrolysis, electrochemical impedance spectroscopy (EIS)) and spectroscopic (XPS, X‐ray absorption near edge structure (XANES), diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), in operando Raman) analysis allows stablishing that electron‐withdrawing ligands promote local electron‐delocalization at the NiO surface, favoring the nucleophilic attack of water to the more electrophilic Ni centers. Furthermore, both Ni electrophilicity and the ability of the C 6 F 5 ─ group to promote proton shuttling aid the deprotonation in the required Ni 2+ →NiOOH reconstruction, thus also improving the OER performance of this system.…”