Progress in liquid phase laser-induced preparation of methanol oxidation electrocatalysts

[ Instrument Network Instrument Development ] Recently, the solid-state liquid phase laser processing and preparation laboratory has obtained the research on the preparation of sulfur- and nitrogen-doped carbon nanotube-supported nickel oxide electrocatalysts (NiO/S, N-CNTs) by liquid phase laser irradiation. Progress and research on the electrocatalytic performance of methanol oxidation. The relevant results are published in full text in Carbon magazine.

Methanol is an important energy carrier. It is liquid under normal temperature and pressure conditions. It has the advantages of convenient transportation and storage, high combustion efficiency, clean and environmental protection. The development of direct methanol fuel cells (PEMFC) using methanol aqueous solution or steam methanol as fuel is the fourth power generation method after hydropower, firepower and atomic power generation, and is one of the effective ways to solve the environmental and energy crisis. At present, electrochemically catalyzed methanol oxidation mainly uses platinum-based noble metal nanomaterials as a catalyst, and the preparation of the catalyst is expensive. Therefore, the development of inexpensive non-precious metal-based methanol oxidation catalysts to solve the general problem of low catalytic activity and poor stability has important research value and scientific significance for promoting the development of PEMFC research.

In recent years, researchers have carried out a lot of fruitful research work on improving the catalytic activity of PEMFC based on nanomaterial structure and defect engineering, such as regulating catalyst size, constructing two-dimensional large specific surface area lamellar nanostructure, defect control and different The atomic doping and the like greatly improve the methanol oxidation catalytic activity of the non-precious metal-based catalyst. However, in the methanol oxidation reaction, in the face of a harsh electrolyte environment, the highly active nanocatalyst material is easily deactivated due to surface structure remodeling, aggregate growth, or adsorption of intermediate species. Therefore, it is necessary to take into account the catalytic activity and stability of the methanol oxidation catalyst.

Based on this, the liquid-phase laser processing and preparation laboratory of the Institute of Solid State Physics proposed from the perspective of catalyst carrier design, and proposed that the carbon nanotubes doped with S and N elements as support carriers and anchor small-sized NiO nanoparticles to enhance methanol. Oxidation catalytic activity and stability. Specifically, high-concentration S and N-doped NiO nanoparticles were prepared by in-situ loading of carbon nanotubes (NiO/S, N-CNTs) by pulsed laser irradiation in a liquid phase environment. During the laser irradiation process, the doping of S and N elements can provide more attachment sites for the nucleation growth of NiO, which accelerates the consumption rate of Ni2+ ion-reactive precursors in the localized high temperature region of the carbon nanotube surface. The size of the supported NiO nanoparticles is reduced; in addition, due to the doping of S and N elements, the anchoring effect of the carbon nanotubes on the NiO nanoparticles is significantly enhanced, so that the contact resistance between the two is reduced, and the interface electron transport is promoted. It has an effect on its electrochemical activity. The electrochemical test results under alkaline conditions show that NiO/S and N-CNTs have good methanol oxidation catalytic performance, and the initial methanol oxidation mass specific activity is 2200 mA/mg. After continuous testing for 40,000 seconds, the mass specific activity retention rate was 65.8%, showing good cycle stability and the methanol saturation concentration could be increased to 13M. This research work provides a new idea for the realization of low-cost and high-efficiency non-precious metal-based methanol oxidation catalysts based on liquid-phase laser preparation and processing technology to achieve carbon nanotube doping.

The research work was funded by the Chinese Academy of Sciences equipment development project, the National Natural Science Foundation and the China Postdoctoral Fund.

(Original title: Liquid-phase laser-induced preparation of NiO/S in solids, progress in research on methanol-oxidation electrocatalysts for N-CNTs)