CN103943869A - Preparation method of film electrode material using graphite coated paper to load NiAu - Google Patents

Abstract

The invention provides a preparation method of graphite-coated paper loaded NiAu film electrode material. Use clay as curing agent, mix clay and graphite evenly and coat on the surface of ordinary paper; dissolve 5-5.5g NH ₄ Cl and 1-1.5g NiCl ₂ in 50mL water to make electrodeposition solution; in electrodeposition solution Keep the graphite-coated paper at a voltage of 1.0V for 20-30min to activate the coated graphite, and then electrodeposit Ni at -1.0V for 160-180min to obtain a paper-graphite-Ni film electrode; paper-graphite-Ni The thin film electrode was placed in 1mmol L ^-1 HAuClO ₄ solution for 2 to 4 minutes to obtain a paper-graphite-NiAu thin film electrode. The invention uses graphite-coated paper, deposits Ni on the surface of conductive graphite-coated paper, and then replaces part of Ni with Au to prepare a pencil-coated paper-loaded NiAu catalyst to improve the catalytic performance of the anode of a direct borohydride fuel cell. . The problem of poor anode activity of the sodium borohydride fuel cell is solved.

Description

A kind of preparation method of graphite-coated paper loaded NiAu film electrode material

technical field

The invention relates to a method for preparing a thin film electrode material, in particular to a method for loading NiAu with graphite-coated paper to catalyze the electro-oxidation performance of borohydride.

Background technique

A direct sodium borohydride fuel cell (DBFC) is a fuel cell in which NaBH ₄ dissolved in an alkaline electrolyte solution is directly used as fuel. Sodium borohydride is a hydrogen storage material with a high hydrogen content (11wt.% for solids and 7.4wt.% for saturated sodium borohydride solutions). Sodium borohydride has a larger volume of hydrogen storage capacity than compressed hydrogen and liquefied hydrogen. NaBH ₄ has faster oxidation kinetics than methanol, and its energy density and cell voltage are also superior to methanol. NaBH ₄ is non-flammable, low in toxicity, non-polluting, does not produce CO ₂ , and is only weakly corrosive, so it has a simple device, small size, convenient storage and transportation, can avoid the risk of explosion, and has superior safety performance. Sodium borohydride can be stored in solution or solid form, and can exist stably in alkaline solution for several months. The catalyst and reaction products can be recycled, and NaBO ₂ , the only by-product of the hydrolysis of NaBH ₄ , is non-toxic to the environment, and can also be used as a raw material for the synthesis of NaBH ₄ , thereby realizing the recycling of resources. DBFC can work at ambient temperature, so the battery is easy to start. From an engineering point of view, NaBH ₄ solution can act as a heat exchange medium to cool the battery without additional cooling plates; the electroosmotic drag of water can be used as a cathode reactant without the need for wetting like hydrogen and air; these properties are important for fuel The design of the battery is beneficial.

Theoretically, the direct electrooxidation of NaBH ₄ can be 8e ^- reaction, see formula (1):

BH ₄ ^- +8OH ^- →BO ₂ ^- +4H ₂ O+8e ^- (1)

In theory, DBFC can use non-platinum _catalysts for NaBH ₄ . NaBH ₄ electrooxidation catalysts are mainly divided into two categories. The hydrolysis reaction, see (2) formula:

NaBH ₄ +2H ₂ O→4H ₂ +NaBO ₂ (2)

_See Kui Cheng; Dianxue Cao; Fan Yang; Dongming Zhang; Peng Yan; Jinling Yin; 242:141-147, and Cao Dianxue, Gao Yinyi, Wang Guiling, Miao Rongrong, Liu Yao. A direct NaBH ₄ –H ₂ O ₂ fuel cell using Ni foam supported Au nanoparticles as electrodes. International Journal of Hydrogen Energy, 2010, 35 :807–813..

Contents of the invention

The purpose of the present invention is to provide a method for preparing a graphite-coated paper-loaded NiAu film electrode material that can improve the catalytic performance of the anode of a direct borohydride fuel cell and solve the problem of poor anode activity of a sodium borohydride fuel cell.

The purpose of the present invention is achieved like this:

The purpose of the present invention is achieved like this:

(1) Use clay as a curing agent, mix the clay and graphite evenly and apply it on the surface of ordinary paper;

(2) Dissolve 5-5.5g NH ₄ Cl and 1-1.5g NiCl ₂ in 50mL water to make electrodeposition solution;

(3) In the electrodeposition solution, keep the graphite-coated paper at 1.0V for 20-30min to activate the coated graphite, and then electrodeposit Ni at -1.0V for 160-180min to obtain a paper-graphite-Ni film electrode;

(4) Finally, put the paper-graphite-Ni film electrode in 1 mmol L ^- ₁ HAuClO4 solution for 2 to 4 minutes to obtain the paper-graphite-NiAu film electrode, that is, graphite-coated paper-supported NiAu catalyst.

The invention uses graphite-coated paper, deposits Ni on the surface of conductive graphite-coated paper, and then replaces part of Ni with Au to prepare a pencil-coated paper-loaded NiAu catalyst to improve the catalytic performance of the anode of a direct borohydride fuel cell. . The disadvantages of high current collector price and decomposition of sodium borohydride are overcome, and the problem of poor anode activity of sodium borohydride fuel cell is solved.

The essence of the present invention is to adopt a battery structure such as a sodium borohydride fuel cell, and use graphite-coated paper to support NiAu as a catalyst to form the anode of the fuel cell.

The invention has the advantage of using the NiAu catalyst supported by graphite-coated paper as the catalyst for the direct electrooxidation of sodium borohydride, which solves the problems of small discharge current of the borohydride fuel anode and easy hydrolysis. No binder is used in the preparation of this electrode material. More importantly, graphite and clay can form a paper-graphite-clay-NiAu cross-linked compound with Ni and Au under the action of an electric field, which not only has good conductivity, but also has high electrocatalytic activity. . The paper-loaded NiAu catalyst is not only extremely rich in graphite, clay, and Ni reserves, but also low in price, which greatly reduces the cost of electrode preparation, and has high catalytic activity, stable performance, easy preparation process, suitable for industrial production, and has industrial application prospects and markets. value.

Detailed ways

In order to better illustrate the effect of the process of the present invention, specific examples are used below to illustrate.

(1) Take a piece of ordinary paper, use clay as curing agent and graphite to evenly mix and coat the surface of the paper, take 1×1cm ^-2 as the research electrode; (2) Dissolve 5g NH ₄ Cl and 1g NiCl ₂ in 50mL In water, it is used for Ni electrodeposition by constant potential method. (3) Keep the graphite-coated paper at a voltage of 1.0V for 20-30min to activate the coated graphite, and then electrodeposit Ni at -1.0V for 160-180min to obtain a paper-graphite-Ni film electrode. (4) Finally, put the paper-graphite-Ni film electrode in 1 mmol L ^- ₁ HAuClO4 solution for 2 to 4 minutes to obtain the paper-graphite-NiAu film electrode, that is, graphite-coated paper-supported NiAu catalyst.

The paper-graphite-NiAu thin film electrode was tested as follows:

1. With paper-graphite-NiAu film as working electrode, carbon rod as counter electrode, and Ag/AgCl as reference electrode, in a solution of 1mol/L NaOH and 0.10mol/L NaBH ₄ , -0.4V vs .Under the voltage of Ag/AgCl, the chronocurrent density reaches 120mA/cm ² .

2. Using paper-graphite-NiAu film as working electrode, carbon rod as counter electrode, and Ag/AgCl as reference electrode, in a solution of 2M NaOH and 0.50M NaBH ₄ , -0.4V vs.Ag/AgCl Under high voltage, the chronocurrent density reaches 350mA/cm ² .

3. Use paper-graphite-NiAu film to catalyze the electrooxidation of NaBH ₄ as the anode, 3mol/L KOH as the anode electrolyte solution, and 1mol/L sodium borohydride as the fuel; use nano-Pd loaded on foamed nickel to catalyze H ₂ O ₂ Direct electroreduction is used as the cathode, with 3mol/L KOH and 0.6mol/L ^-1 H ₂ O ₂ as the catholyte; Nafin-115 proton exchange membrane as the diaphragm; the maximum power density of the battery is 245mW/cm ^-2 .

Claims (1)

1. a preparation method for coated with graphite paper load NiAu thin-film electrode material, is characterized in that:

(1) make curing agent with clay, after clay is evenly mixed with graphite, be coated on plain paper surface;

(2) by 5～5.5g NH ₄cl and 1～1.5g NiCl ₂be dissolved in 50mL water and make electrodeposit liquid;

(3) in electrodeposit liquid, the paper that scribbles graphite is kept to 20～30min under 1.0V voltage, to activate the graphite of coating, then deposit N i160～180min under-1.0V, obtains paper-graphite-Ni membrane electrode;

(4) finally by paper-graphite-Ni membrane electrode at 1mmol L ^-1hAuClO ₄in solution, leave standstill 2～4 minutes, obtain paper-graphite-NiAu membrane electrode.