dhydrogène

Dhydrogène is a term sometimes used to refer to dihydrogen, the diatomic molecule consisting of two hydrogen atoms (H2). In this sense, dhydrogène denotes the simplest and most abundant element in the universe, existing throughout space primarily as molecular hydrogen, while on Earth it is mainly present in compounds such as water and hydrocarbons rather than as a free gas under ordinary conditions.

Dihydrogen is a colorless, odorless, and highly flammable gas at room temperature. It has a molecular weight of 2.016 g/mol. Its boiling point is about −252.87 °C and its melting point around −259.16 °C, making it a cryogenic liquid at sufficiently low temperatures. The H–H bond is strong and nonpolar, leading to low solubility in many solvents and high diffusion rates. Hydrogen is a versatile reducing agent and, when used as a fuel or energy carrier, releases energy upon combustion or in fuel cells.

Industrial production mainly relies on steam methane reforming and electrolysis of water, with growing interest in “green” hydrogen produced by renewable-powered electrolysis. It is also obtained from natural gas reforming processes and various chemical manufacturing streams. Dihydrogen plays a central role in energy transition efforts, as a clean energy carrier when produced from low-carbon sources and used in applications such as power generation, transportation, and various chemical syntheses.

Safety considerations emphasize that hydrogen is extremely flammable and can form explosive mixtures with air; leaks require prompt detection and proper ventilation, with storage and handling designed to minimize ignition risk.