With the development of hydrogen fuel cell technology, the market's demand for hydrogen is increasing, and finding a way to produce clean and efficient hydrogen on a large scale has become a must-answer question. The technology of hydrogen production by electrolysis of water is relatively mature, which is vital to the use of clean and sustainable energy in the future. Hydrogen production by electrolysis of water is to dissociate water molecules into hydrogen and oxygen through an electrochemical process under the action of direct current, which are separated out at the anode and cathode. According to different electrolytes, hydrogen production by electrolysis of water is mainly divided into three methods: alkaline (ALK) electrolyzed water, proton exchange membrane (PEM) electrolyzed water and solid oxide electrolytic cell (SOEC) electrolyzed water.
Megawatt PEM water electrolysis hydrogen production project enters the demonstration stage
At present, there are already megawatt-level PEM electrolyzed water hydrogen production demonstration projects underway, and PEM electrolyzed water hydrogen production equipment has made substantial progress in research and development and application.
PEM water electrolysis hydrogen production technology needs to break through the cost dilemma
Although PEM water electrolysis hydrogen production technology has good performance, high hydrogen productivity and high energy efficiency, high investment and operating costs are still the main problems to be solved urgently for PEM water electrolysis hydrogen production. Therefore, reducing the cost of catalysts and PEM materials, especially the noble metal loading of the anode and cathode electrocatalysts, is the research focus of the development of PEM water electrolysis hydrogen production technology.
Research status of PEM materials. At present, most of the proton exchange membranes used in water electrolysis hydrogen production are perfluorosulfonic acid membranes, and the preparation process is complicated, which has long been monopolized by American and Japanese companies. The preparation of organic/inorganic nanocomposite proton exchange membranes by introducing inorganic components has the flexibility of organic membranes and good thermal properties, chemical stability and mechanical properties of inorganic membranes, which has become a research hotspot in recent years. In addition, the use of cheap materials such as polyaryletherketone and polysulfone to prepare fluorine-free proton exchange membranes is also the development trend of proton exchange membranes.
Research status of oxygen evolution catalysts. At present, Ir or IrO2 is the preferred anode material for electrocatalysts in PEM electrolytic cells. Researchers mainly use the mixture of RuO2 and IrO2 to maintain the high activity of RuO2 and the high stability of IrO2, thereby obtaining higher catalytic oxygen evolution activity. Research is to reduce the content of precious metals in the catalyst while maintaining the higher activity of the catalyst by adding inert non-precious metal oxides. However, in order to significantly reduce the amount of precious metals in the PEM electrolytic cell, a nano-scale catalyst structure must be used. The research on the nanostructure of the OER catalyst and its carrier is still in the early stage, and more in-depth research is needed.
Research status of hydrogen evolution catalysts. The existing commercial hydrogen evolution catalyst has a Pt loading of 0.4-0.6 mg/cm2, and the high cost of precious metal materials hinders the rapid promotion and application of PEM water electrolysis hydrogen production technology. At present, the high-efficiency hydrogen evolution performance of Pt-based precious metals is mainly improved by preparing Pt surfaces with nanostructures, depositing a single layer of Pt on low-cost materials, and alloying precious metal electrocatalysts with other materials. In addition, research on non-precious metal HER catalysts, such as metal sulfides, metal selenides and metal phosphides, has also progressed.
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