Ball-flower-shaped Ni nanoparticles on Cu modified TiO2 nanotube arrays for electrocatalytic oxidation of methanol

Plasma Electrolytic Oxidation of Titanium in Ni and Cu Hydroxide Suspensions towards Preparation of Electrocatalysts for Urea Oxidation

The increasing climate crisis requires an improvement in renewable energy technologies. One of them are fuel cells, devices that are capable of generating electricity directly from the chemical reaction that is taking place inside of them. Despite the advantages of these solutions, a lack of the appropriate materials is holding them back from commercialization. This research shows preliminary results from a simple way to prepare black TiO₂ coatings, doped with Cu or Ni using the plasma electrolytic oxidation process, which can be used as anodes in urea-fueled fuel cells. They show activity toward urea oxidation, with a maximum current density of 130 μA cm^-2 (@1 V vs. Hg|HgO) observed for Cu-enhanced TiO₂ and low potential of only 0.742 V (Vs Hg|HgO) required for 50 μA cm^-2 for Ni-enhanced TiO₂. These results demonstrate how the PEO process can be used for the preparation of TiO₂-based doped materials with electrocatalytic properties toward urea electrooxidation.

A novel environmental nano-catalyst of zeolite amended with carbon nanotube/silver nanoparticles decorated carbon paste electrode for electro-oxidation of propylene glycol

A novel environmental nano-catalyst based on zeolite (ZE) adjusted with carbon nanotube/silver nanoparticles (Ag/CNT) ornamented carbon paste electrode (CPE) is used for electrochemical oxidation of propylene glycol (PG) in 0.5 M H₂SO₄ solution. The techniques like cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) are utilized to achieve the catalytic activity performance. Surface characteristics are achieved by means of scanning electron microscope (SEM) and Energy dispersive X-ray analysis (EDX) techniques. Enhancing the loading magnitude of CNT into catalyst's ingredient can meaningfully develop the catalytic activity of the electrocatalyst towards propylene oxidation. The impact of altering the concentration of propylene glycol and the scanning rate on the resulting electrocatalyst performance during the oxidation cycle is considered. Chronoamperograms present an amplify of the steady state oxidation current density values after addition of these nano-catalysts. A promising catalytic stability of nano-catalyst has been achieved in electing its use for propylene glycol electro-oxidation in fuel cells applications.

Nickel nanocrystal/nitrogen-doped carbon composites as efficient and carbon monoxide-resistant electrocatalysts for methanol oxidation reactions

High-performance electrocatalysts for the methanol oxidation reaction (MOR) are the key to advance the application of direct methanol fuel cells. Pt-Based electrocatalysts for the MOR are limited due to their high cost, low stability and poor resistance to carbon monoxide (CO) poisoning. The development of non-noble metal-based electrocatalysts for the MOR with high activity and good stability is desired, but it remains a challenge. Herein, we report a simple strategy to prepare nickel nanocrystals embedded in a nitrogen-doped carbon matrix (Ni/N-C composite) by pyrolysis of Ni-coordinated polyaniline-poly(vinyl alcohol) hydrogels. These in situ generated Ni nanocrystals serve as active electrocatalysts for the MOR, while the nitrogen-doped carbon matrix serves as a conductive support to facilitate electron transfer and also to protect the active Ni nanocrystals. The optimal Ni/N-C@500 electrocatalyst shows a high MOR activity of 147 mA cm-2 at 1.66 V vs. the RHE in alkaline methanol solution, which is outstanding among Ni-based MOR electrocatalysts. Ni/N-C@500 also shows better stability than the Pt/C catalyst in the long-term MOR test at high current densities. Upon CO poisoning, Ni/N-C@500 retains 85% of its MOR activity, far exceeding the performance of the Pt/C catalyst (61% retention). Owing to its facile synthesis, outstanding activity and high stability, the Ni/N-C@500 composite is promising as a low-cost, efficient and CO-resistant electrocatalyst for the MOR.

Facile synthesis of a mechanically robust and highly porous NiO film with excellent electrocatalytic activity towards methanol oxidation

Considerable research is being conducted in searching for effective anode catalysts in alkaline direct methanol fuel cells (DMFCs). Although significant progress has been achieved, it is still challenging to prepare non-Pt catalysts with both excellent activity and good durability. Herein, a highly porous NiO film is developed by a facile and fast anodization approach. The anodic NiO film demonstrates a high surface area, large mesopore volume and small crystallite size, leading to facilitated adsorption of reaction species, easy electrolyte penetration and fast reaction kinetics. Furthermore, as anodic NiO is grown in situ on a metallic substrate with strong adhesion strength and good electrical contact, it can be used directly as an anode catalyst for methanol oxidation without the need to add any binder or conducting agent. Such an additive-free approach greatly expedites the catalyst preparation process. The anodic NiO shows lower methanol oxidation potential, higher oxidation current and better catalytic durability than most of the state-of-the-art Ni-based catalysts reported elsewhere. As anodization is a simple, low cost and easily scaled up method, the work described here provides an exciting direction to speed up the practical application of alkaline DMFCs.