Foam Synthesis of Nickel/Nickel (II) Hydroxide Nanoflakes Using Double Templates of Surfactant Liquid Crystal and Hydrogen Bubbles: A High-Performance Catalyst for Methanol Electrooxidation in Alkaline Solution

Abstract

This work demonstrates the chemical synthesis of two-dimensional nanoflakes of mesoporous nickel/nickel (II) hydroxide (Ni/Ni(OH)2-NFs) using double templates of surfactant self-assembled thin-film and foam of hydrogen bubbles produced by sodium borohydride reducing agent. Physicochemical characterizations show the formation of amorphous mesoporous 2D nanoflakes with a Ni/Ni(OH)2 structure and a high specific surface area (165 m2/g). Electrochemical studies show that the electrocatalytic activity of Ni/Ni(OH)2 nanoflakes towards methanol oxidation in alkaline solution is significantly enhanced in comparison with that of parent bare-Ni(OH)2 deposited from surfactant-free solution. Cyclic voltammetry shows that the methanol oxidation mass activity of Ni/Ni(OH)2-NFs reaches 545 A/cm2 gcat at 0.6 V vs. Ag/AgCl, which is more than five times higher than that of bare-Ni(OH)2. Moreover, Ni/Ni(OH)2-NFs reveal less charge transfer resistance (10.4 Ω), stable oxidation current density (625 A/cm2 gcat at 0.7 V vs. Ag/AgCl), and resistance to the adsorption of reaction intermediates and products during three hours of constant-potential methanol oxidation electrolysis in alkaline solution. The high-performance electrocatalytic activity of Ni/Ni(OH)2 nanoflakes is mainly derived from efficient charge transfer due to the high specific surface area of the 2D mesoporous architecture of the nanoflakes, as well as the mass transport of methanol to Ni2+/Ni3+ active sites throughout the catalyst layer.

Synthesis and study of enhanced electrochemical properties of NiO nanoparticles deposited on TiO2 nanotubes

“…It is proposed that methanol is oxidized on NiO NPs/TiO 2 NTs‐N 2 electrode through the reaction with NiO(OH) to form Ni(OH) 2 ; that is, NiO(OH) acts as electron transfer mediator for the oxidation process. [ 73 ]…”

“…It is proposed that methanol is on NiO NPs/TiO 2 NTs-N 2 electrode through the reaction with NiO(OH) to form Ni(OH) 2 ; that is, NiO(OH) acts as electron transfer mediator for the oxidation process. [73] The catalytic activity of NiO NPs/TiO 2 NTs-N 2 for methanol oxidation was assessed by CV. Figure 11 shows the cyclic voltammograms of NiO NPs/TiO 2 NTs-N 2 in 2-M KOH and 0.5-M CH 3 OH.…”

Carbon black‐heteroatom‐doped graphene aerogel hybrid supported platinum nanoparticles as electrocatalysts for oxidation of methanol and formic acid

“…The CPE is corresponding to the double layer capacitance and the charge transfer resistance, C 2 and R 3 are the electrical elements related to the adsorption of reaction intermediates for methanol oxidation. 77,78 In a study, it was observed that the R ads value decreased with the decrease in the R ct value during methanol oxidation. 79 The sum of R ct and R ads is defined as the total resistance involved in the Faradaic process (R far ) and lower resistances indicated more efficient in methanol oxidation.…”

“…The suitable circuit was shown in the inset of Figure 14A. The CPE is corresponding to the double layer capacitance and the charge transfer resistance, C 2 and R 3 are the electrical elements related to the adsorption of reaction intermediates for methanol oxidation 77,78 . In a study, it was observed that the R ads value decreased with the decrease in the R ct value during methanol oxidation 79 .…”

Hydrazine High-Performance Oxidation and Sensing Using a Copper Oxide Nanosheet Electrocatalyst Prepared via a Foam-Surfactant Dual Template

“…Recently, the soft-template approach as the chemical method has been widely exploited because of its one-step route that produces high-surface-area mesoporous nanostructured compounds [ 52 , 53 , 54 ]. Using this approach, our research group reported a foam-surfactant dual template (FSDT) approach to produce mesoporous Ni/Ni(OH) 2 2D nanoarchitecture (nanoflakes) via chemical deposition from a hexagonal lyotropic surfactant template using a sodium borohydride reducing agent [ 55 ]. The Ni/Ni(OH) 2 nanoflake catalyst has shown substantial enhancement of the electrochemical nature of methanol and urea oxidation and glucose sensing reactions [ 51 ].…”