Study Of Ammonia Electrolysis For Hydrogen Production Based On Pt-Ir Catalysis And Its The Catalytic Kinetic Properties

Ammonia electrolysis for hydrogen production is a new route of hydrogen production derived from the development of electrochemistry in recent years because electrical management will be simpler than thermal management in engineering applications.Due to the low energy consumption feature of ammonia electrolysis,ammonia electrolysis cell can be installed in fuel cell vehicle(ship)for online hydrogen supply,avoiding vehicle(ship)carrying high-pressure hydrogen tank(35～70 MPa),which can reduce hydrogen compression power consumption and hydrogen cost,and improved vehicle(ship)safety greatly.At present,the on-site production of hydrogen by ammonia electrolysis for hydrogen refueling stations or vehicle(ship)power systems is gaining attention,and some western countries are actively developing related technology.This paper focuses on optimizing the preparation process of the ammonia electrolysis catalyst and the problem of catalytic kinetics in the context of renewable energy sources such as wind and photovoltaics.The study mainly includes the influences of Pt-Ir electrodeposition potentials on hydrogen production with ammonia electrolysis,exploring the catalytic kinetics influencing factors of ammonia electrolysis through the electrochemical impedance,and the technical solutions of hydrogen supply with ammonia electrolysis based on Pt-Ir catalysts at optimal performance.It is shown that Pt-Ir bimetals are a good catalyst for ammonia electrolysis,which can be prepared by electrodeposition.The deposition potential has a strong influence on the morphology and atomic ratio of catalysts.The catalyst crystal structure is mainly dominated by(111)and(200)crystal planes with elemental valence states including 0,+2,+4 valence,and active electrochemical area up to 20.4 m2/g.With the negative shift of potential,Ir could not be deposited at low potentials.The initial anodic potential of ammonia electrolysis at room temperature is reduced by about 160 mV due to the presence of Ir.By studying the kinetics of ammonia electrolysis,it is found that the deactivation of Pt-Ir catalyst is a false appearance,and the anodic diffusion resistance of ammonia in solution is the main reason for the deactivation of ammonia electrolysis,which can be improved by increasing the temperature.At 80℃,the initial decomposition voltage drop of ammonia is 0.31V.At a current density of 100 mA/cm2,the ammonia electrolysis voltage is about 0.5V,and the hydrogen production rate is about 51 mL/h·cm2.For the technical route of ammonia electrolysis for fuel cell hydrogen supply at atmospheric pressure,it is possible to achieve up to about 45%of the fuel cell’s electrical output to the outside by heating the ammonia electrolytic cell at a high current density(>100 mA/cm2).This technology route can reduce the electric abandonment rate of renewable energy in China,avoid the use of high-pressure hydrogen storage tanks and the construction of hydrogen refueling stations in the development of hydrogen fuel cell vehicles in China,and at the same time may achieve large-scale carbon reduction in the future field of heavy-duty trucks and freight ships.The use of ammonia for energy storage is a brand new concept in China,and ammonia electrolysis to produce hydrogen finds a breakthrough for applying renewable energy in hydrogen energy in hydrogen energy.Instead of hydrogen,the use of ammonia can realize the whole industrial chain from synthesis to application without carbon emission,which fits the development route of clean energy in China and will lay the groundwork for the early realization of the "2060 carbon neutral" plan in China.