Fabrication method of porous gas diffusion electrode

Abstract

The present invention discloses a porous gas diffusion electrode production method, which comprises: placing carbon supported noble metal catalyst powder in a proper amount of a dispersant, and completely dispersing to obtain a suspension; adding a proper amount of a hydrophobic agent to the suspension, and completely mixing to obtain a mixed solution; stirring the mixed solution under heating to form a bulky viscous coating material; uniformly coating the viscous coating material on a hydrophobic carbon paper; and adopting the viscous coating material coated on the hydrophobic carbon paper to carry out integrated pressing adhesion on the hydrophobic carbon paper and a waterproof porous air permeability film to obtain the porous gas diffusion electrode. According to the present invention, the carbon supported noble metal catalyst is coated on the waterproof porous air permeability film having the hydrophobic air permeability effect to prepare the porous gas diffusion electrode, and no excessive complex auxiliary agent is not introduced during the production process, such that the production is simple, the noble metal consumption is low, and the produced porous gas diffusion electrode has characteristics of uniform and flat catalysis layer, no crack, firm bonding and good response performance.

Description

technical field [0001] The invention relates to a manufacturing method of an electrode used in an electrochemical gas sensor, in particular to a manufacturing method of a porous gas diffusion electrode. Background technique [0002] Electrochemical gas sensors are widely used in the detection of toxic gases due to the advantages of rapid response, high sensitivity, and good selectivity. The overall performance of electrochemical gas sensors depends on electrodes, catalysts, diaphragms, and preparation processes, among which determine the sensor response is the electrode. Electrodes used in electrochemical gas sensors are generally porous gas diffusion electrodes, which consist of a catalytic layer and a waterproof and gas-permeable membrane. The catalytic layer is mainly composed of a noble metal catalyst and a water-repellent agent that acts as a hydrophobic and air-repellent gas; the catalytic layer is mostly fixed on the water-repellent air-permeable membrane by screen p...

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Problems solved by technology

The disadvantages of the electrode prepared by the above method are: first, pure noble metal is used as the catalytic layer, and the amount of noble metal catalyst is large and the cost is high, resulting in high cost of the entire electrochemical gas sensor; The "ink" needs to add more additives, so after the screen printing is completed, the electrode needs to be dried, cleaned and other steps, and the process is relatively complicated; the third is that the catalytic layer and the hydrophobic and breathable membrane are combined by physical force, and the bonding It is not firm, and the catalytic layer is prone to loosening or even falling off, which affects the performance of the sensor

However, the hydrophobic and breathable membrane used in this patent is a hydrophobic treated carbon paper

Carbon paper or carbon cloth materials are not suitable for use in electrochemical gas sensors, because the loose interlayer structure of carbon paper will lead to the leakage of liquid electrolyte

If the precious metal catalyst loaded on the conductive carbon black is directly coated on the waterproof porous membrane according to the method introduced in CN100364158C, the phenomenon that the response time will be greatly prolonged due to the difference in the conductivity of the catalytic layer and the air-permeable layer

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