Bifunctional hexagonal Ni/NiO nanostructures: influence of the core–shell phase on magnetism, electrochemical sensing of serotonin, and catalytic reduction of 4-nitrophenol

Abstract

Ni 0 /NiO (nickel/nickel oxide) core-shell nanostructures were synthesized through a facile combustible redox reaction. Remarkably, the hetero-phase boundary with different crystalline orientations offered dual properties, which helped in bifunctional catalysis. Presence of a metallic Ni phase changed physicochemical properties and some emerging applications (magnetic properties, optical conductivity, electrochemical sensitivity, catalytic behaviour) could be foreseen. Moreover, formation of a NiO layer on metal surface prevented magnetism-induced aggregation, arrested further oxidation by hindering oxygen diffusion, and acted as a good sorbent to enhance the surface adsorption of the analyte.Hexagonal Ni/NiO nanostructures manifested well-defined ferromagnetic behavior and the catalyst could be collected easily at the end of the catalytic reduction. Ni/NiO core-shell catalysts at the nanoscale had outstanding catalytic performance (reduction of 4-nitrophenol to 4-aminophenol) compared with pure NiO catalysts beyond a reaction time of $9 min. The estimated sensitivity, limit of detection and limit of quantification towards the electrochemical sensing of serotonin were 0.185, 0.43 and 1.47 mM mA À1 , respectively. These results suggest that a bifunctional Ni/NiO nanostructure could be a suitable catalyst for electrochemical detection of serotonin and reduction of 4-nitrophenol.

Phytochemical-Assisted Green Synthesis of Nickel Oxide Nanoparticles for Application as Electrocatalysts in Oxygen Evolution Reaction

“…Figure 1 shows the structural properties of the synthesized NiO x nanoparticles using different extracts after calcination at 300 113) and (006) crystal planes of cubic NiO x [11,12]. These peaks were in agreement with the standard JCPDS card no.…”

Excellent Oxygen Evolution Reaction of Activated Carbon-Anchored NiO Nanotablets Prepared by Green Routes

“…Different from the NiO nanoparticles, the AC-NiO nanotablets revealed three additional Raman peaks at 1360, 1586, and 2856 cm -1 , attributing to D, G, and 2D bands of AC nanosponges Figure 4a shows the crystallographic properties of the NiO nanoparticles and the AC-NiO nanotablets. In XRD patterns, both the NiO nanoparticles and the AC-NiO nanotablets exhibited the diffraction peaks of 37.2, 43.2, 62.9, 75.4, and 79.3° from (111), ( 200), ( 220), (311), and (222) crystal planes of cubic NiO (JCPDS card no: 04-0835), respectively [55,56]. The only one thing different from each other was that the AC-NiO composites include an additional peak at 26.5°, arising from the (002) phase of AC [45][46][47] (see also Figure S2).…”

Transition metal oxide based non‐enzymatic electrochemical sensors: An arising approach for the meticulous detection of neurotransmitter biomarkers

“…As an example, Manigandan et al fabricated a coreshell nanostructure by hybridizing Ni with NiO, which resulted in enhanced physicochemical properties of the composite. [140] The thus prepared Ni/NiO core-shell was used for the voltammetric sensing of 5-HT with a detection limit of 0.43 µM.…”