Platinum

Platinum is a dense, malleable, ductile, and highly unreactive precious metal with the chemical symbol Pt and atomic number 78. Belonging to the transition metals and forming part of the platinum group metals (PGMs)—which include palladium, rhodium, iridium, ruthenium, and osmium—it is one of the rarest and most valuable elements on Earth. Known for its lustrous silvery-white appearance, remarkable resistance to corrosion, and exceptional catalytic properties, platinum plays a vital role in industry, technology, medicine, and global economics.

Discovery and Historical Background

The earliest known use of platinum dates back to pre-Columbian South America, where indigenous peoples of Ecuador and Colombia worked naturally occurring platinum-gold alloys for decorative purposes. The element was formally recognised by European scientists in the eighteenth century, when Antonio de Ulloa reported on a white metal resistant to melting during his travels in 1735.
By the late eighteenth century, platinum became the focus of extensive scientific study. Its name derives from the Spanish word platina, meaning “little silver.” The element’s rarity and unusual properties soon led to its adoption in fine jewellery, laboratory apparatus, and industrial processes requiring chemical stability at high temperatures.

Physical and Chemical Properties

Platinum is one of the most chemically inert and stable metals known.

• Atomic number: 78
• Atomic weight: 195.08
• Density: 21.45 g/cm³ (almost twice that of lead)
• Melting point: 1,768°C
• Boiling point: 3,825°C
• Crystal structure: Face-centred cubic (fcc)

Platinum resists oxidation, does not corrode in air, and is unaffected by most acids. It dissolves only in aqua regia (a mixture of nitric and hydrochloric acids) and molten alkalis. Its excellent conductivity, thermal stability, and catalytic efficiency make it indispensable in a wide range of industrial and technological contexts.

Occurrence and Extraction

Platinum is among the rarest elements in Earth’s crust, with an average abundance of approximately 0.005 parts per million. It occurs naturally both as native platinum and in ores such as sperrylite (PtAs₂) and cooperite (PtS), often associated with nickel and copper sulphides.
Major platinum-producing regions include:

• South Africa, which accounts for over 70% of global production, particularly from the Bushveld Complex.
• Russia, especially the Norilsk region.
• Zimbabwe, Canada, and the United States (Montana).

Extraction involves several steps:

1. Mining and concentration of platinum-bearing ores.
2. Smelting and refining, during which platinum is separated from nickel, copper, and other PGMs using chemical and electrochemical methods.
3. Purification, yielding high-purity platinum metal for industrial and commercial use.

Due to the complexity and cost of extraction, recycling from spent catalysts, jewellery, and electronics has become an essential secondary source, accounting for roughly 30% of global supply.

Everyday Applications

While platinum is a precious and expensive metal, it features in many aspects of everyday life—directly or indirectly—through its exceptional durability, beauty, and functionality.

• Jewellery and Luxury Goods: Platinum’s bright lustre, tarnish resistance, and hypoallergenic nature make it a preferred metal for rings, watches, and high-end accessories. Its rarity gives it symbolic value, often associated with prestige and permanence.
• Automobiles: The catalytic converter, fitted to nearly every petrol and diesel vehicle, uses platinum to convert toxic exhaust gases—such as carbon monoxide, hydrocarbons, and nitrogen oxides—into less harmful emissions. This is one of platinum’s most widespread and crucial uses.
• Medical Devices: Platinum is used in pacemakers, catheters, and neurosurgical electrodes because of its biocompatibility and resistance to corrosion inside the human body.
• Electronics: Thin layers of platinum are used in computer hard drives, LCD panels, and thermocouples for precise temperature measurement.

Industrial and Technological Applications

Platinum’s industrial importance is immense, driven primarily by its catalytic, electrical, and thermal properties.

• Catalysis: Platinum serves as a heterogeneous catalyst in numerous chemical reactions. It is used in the production of nitric acid, fertilisers, silicones, and fuels, and in hydrogenation and dehydrogenation processes in the petrochemical industry.
• Petroleum Refining: Platinum-based catalysts are essential in reforming hydrocarbons to produce high-octane petrol and aromatic hydrocarbons used in plastics and synthetic fibres.
• Glass Manufacturing: Platinum equipment—especially bushings and stirrers—is employed in the production of high-quality glass and fibreglass, since it withstands intense heat and does not contaminate the product.
• Electronics and Sensors: Platinum’s stability and conductivity make it ideal for electrodes, thermocouples, and laboratory crucibles used in high-temperature environments.
• Fuel Cells and Hydrogen Technology: Platinum is a critical catalyst in hydrogen fuel cells, where it facilitates the reaction between hydrogen and oxygen to produce electricity. This technology is key to the development of clean energy systems and zero-emission vehicles.

Medical and Pharmaceutical Applications

Platinum compounds are also used extensively in modern medicine, most notably in cancer therapy.

• Cisplatin, Carboplatin, and Oxaliplatin are platinum-based chemotherapy drugs that inhibit cancer cell division by binding to DNA. These have revolutionised the treatment of various cancers, including testicular, ovarian, bladder, and lung cancers.
• Implantable Medical Devices: Because platinum is non-reactive and durable, it is used in prosthetic implants, dental equipment, and surgical instruments.

Economic Significance

Platinum holds a unique position in the global economy, bridging the worlds of luxury commodities and strategic industrial resources.

• Market Value: Platinum consistently ranks among the most valuable metals, though its price fluctuates with demand from automotive and investment sectors.
• Global Trade and Investment: It is traded on commodity exchanges and forms the basis for exchange-traded funds (ETFs) and bullion investments, often compared to gold.
• Strategic Resource: Its role in clean energy, chemical processing, and environmental protection makes platinum a critical material in the transition to sustainable technologies.
• Industrial Demand: The largest demand segment is the automotive industry, followed by industrial catalysts, jewellery, and investment holdings.
• Recycling Industry: The recovery of platinum from spent automotive catalysts and electronic waste represents a growing circular economy sector, providing both environmental and economic benefits.

Environmental and Sustainability Aspects

Although platinum contributes to environmental protection through emission control and green technologies, its extraction and processing pose environmental challenges.

• Mining Impact: Platinum mining can result in land degradation, water pollution, and carbon emissions if not carefully managed.
• Recycling and Conservation: Increased efforts are being made to recycle platinum from used catalysts, electronics, and industrial scrap, reducing the strain on primary resources.
• Sustainable Energy Transition: Platinum plays a vital role in hydrogen production, storage, and fuel cell technology, positioning it as a key enabler of low-carbon economies.

Emerging and Future Applications

As industries shift toward sustainability and high-performance technologies, platinum’s relevance continues to grow.

• Hydrogen Economy: Platinum is at the core of hydrogen fuel cell development, which promises to power electric vehicles and renewable energy systems efficiently and cleanly.
• Green Chemistry: Platinum catalysts are being optimised for CO₂ reduction, ammonia synthesis, and water electrolysis, aiding in decarbonisation efforts.
• Nanotechnology and Electronics: Platinum nanoparticles are being explored for advanced sensors, batteries, and data storage devices, where their chemical stability enhances performance.
• Biomedical Engineering: Research is ongoing into platinum-based nanomaterials for targeted drug delivery and biosensing applications.

Summary of Practical Relevance

Platinum’s exceptional stability, beauty, and functionality have made it indispensable across multiple domains—from luxury goods to life-saving technologies. As the world pivots towards cleaner energy and sustainable industries, platinum’s catalytic role in reducing pollution and enabling hydrogen power ensures that this rare metal remains not only a symbol of prestige but also a cornerstone of modern industrial progress and environmental innovation.