Platinum: Behind my good looks, I am also quite capable!

Platinum, element number 78 in the periodic table.

Platinum was used later than gold. In more than 700 years BC, the ancient Egyptians were able to process some platinum jewelry. The Indians in Central America also used platinum jewelry before Columbus discovered the New World. As the Spanish explored Africa and America, they found a white metal mixed with gold in the rivers of Ecuador, which was called "inferior silver". In 1748, scientists finally confirmed that it was a new element through research.

The content of platinum in the earth's crust is less than that of gold. It is often dispersed in a variety of minerals with other platinum group elements. Natural platinum in the form of a single element is found in gold mines or other platinum group element mines, such as palladium-platinum ore.

More than 100 years ago, British chemist David created a platinum wire alcohol lamp, which was popular in Europe for many years. This alcohol lamp uses platinum wire dipped in alcohol to burn. The burning alcohol can make the temperature of the platinum wire reach a red-hot level, thus emitting a brighter light than ordinary flames. Some people studied the principle and found that it was because the platinum wire catalyzed the oxidation of alcohol, so that the alcohol burned more violently on the surface of the platinum wire. According to this idea, people put the platinum wire in the lid of the container containing alcohol. When the bottle cap is opened, the alcohol on the surface of the platinum wire can react with the oxygen in the air, and after a while, the alcohol vapor can be ignited and used for lighting.

The excellent catalytic properties of platinum wire are due to the special extranuclear electron arrangement structure. Platinum and other platinum group elements have the characteristics of making catalysts, especially platinum can adsorb with many charged species to form active substances, thereby promoting reactions. In the automotive industry, platinum is used to catalyze low concentrations of unburned hydrocarbons in automobile exhaust and oxidize them into carbon dioxide and water; in the field of petrochemicals, platinum is a good hand at oil reforming and can improve the quality of gasoline. Platinum has the ability to adsorb hydrogen, making it stand out in new energy. People make platinum into electrodes for fuel cells to promote the room temperature reaction of hydrogen and oxygen. However, platinum catalysts also have their shortcomings, such as being expensive and easy to cause catalyst poisoning. Catalyst poisoning is not really poisoning, but when encountering certain substances, platinum will first react with these substances and lose its catalytic performance. Therefore, people are constantly looking for alternatives to platinum catalysts. Of course, there are also companies that specialize in recycling platinum catalysts, which regenerate poisoned platinum catalysts through means such as charring to restore their activity.

Another use of platinum is the development of platinum-containing drugs. Some people worry that drugs made of precious metals will be very expensive, but in fact they are not expensive. In 1969, scientist Rosenberg announced an anti-tumor drug - cisplatin. This discovery aroused the interest of many scientists in the research on the mechanism of platinum-containing drugs, and then the second and third generations appeared. Today, injectable cisplatin is a first-line commonly used chemical drug in cancer treatment. It can inhibit the DNA replication of cancer cells, but it has strong side effects and will be accompanied by severe nausea, vomiting and other adverse reactions. At present, researchers are studying to improve the tolerance of platinum-containing drugs.

In recent years, divalent platinum compounds have become popular. Photosensitive groups are added to divalent platinum compounds to assist photoactivated cancer chemotherapy; divalent platinum compounds with planar quadrilateral structures are used to produce organic light-emitting diodes that can emit white light. These divalent platinum compounds and polymers made of photosensitizers and organic photovoltaic materials have allowed people to discover more new uses for platinum.

(The author is a chemistry teacher at Wuhan No. 20 Middle School and a member of the Wuhan Scientists Science Popularization Group)