One widely used method to produce hydrogen is to use electricity to split water. Hydrogen is the clean energy source needed for fuel cells, batteries and zero-emission vehicles. During the electrolysis of water, one of the two main reactions will occur, called the oxygen evolution reaction (Oxygen Evolution Reaction). This reaction is very slow, which greatly limits the efficiency of the entire water splitting process. Researchers are focused on developing better catalysts, materials that can speed up reactions while remaining neutral. Currently, the most effective catalysts are made from precious metals like ruthenium and platinum, which are both expensive and rare.

　　The Indian Institute of Technology team developed a low-cost catalyst by combining cobalt oxide with sodium phosphate. Ritambhara Gond, a doctoral student at the Materials Research Center (MRC) of the Indian Institute of Technology, said that compared with the current most advanced RuO2 (ruthenium dioxide) catalyst, the cost of the new material is more than 200 times lower, and the reaction speed is also faster. And the material could facilitate large-scale applications in devices such as metal-air batteries, fuel cells and electric vehicles.

　　When water is decomposed using electricity under the action of a catalyst, hydrogen atoms will receive electrons from one electrode (negative electrode) to form hydrogen gas, while the positive electrode will evolve oxygen (oxygen evolution reaction). Research members mainly focus on accelerating the latter reaction. Catalysts made of metals such as platinum or ruthenium waste the least energy during the oxygen evolution reaction, so they are most efficient and react faster. However, the high cost and scarcity hinder the large-scale application of this catalyst.

　　To develop a low-cost alternative, the Indian Institute of Technology team used metaphosphates, a salt layer used in energy storage applications but not in catalysis. The researchers roasted sodium metaphosphate and cobalt oxide in an oxygen-free furnace with argon gas, forming a partially burnt carbon "sheet" covered with cobalt oxide crystals composed of sodium metaphosphate.

　　Gond said: "The metaphosphate forms a strong framework that keeps the cobalt oxide intact and shows high stability after the catalytic reaction." This allows the catalyst to remain active over multiple catalytic cycles, Achieve long-term durability. In addition, the carbon bed also increases the catalyst's electrical conductivity, thereby increasing efficiency.

　　The researchers found that compared to other catalysts, their catalyst's diffusion flow density (that is, how quickly a reaction can occur) was even higher than that of the ruthenium dioxide catalyst, showing stronger catalytic activity. "We are now planning to test this catalyst in a metal-air battery and water splitting device," Gond said.

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