Green hydrogen is set to play an important role in the future energy system: it can be used for storing chemical energy, as a raw material for the chemical industry, and for producing climate‑friendly fuels. Green hydrogen can be generated in a nearly climate‑neutral manner if the energy used for electrolysis—the process of splitting water into its elements—comes from solar or wind power. However, special catalysts are needed to speed up the formation of hydrogen and oxygen at the two electrodes.