Researchers have discovered that atoms can be mixed, separated, and recombined within the same experiment, providing a pathway to a record-breaking catalyst for green hydrogen production. In their study, the team created nanoscale particles containing only a few dozen platinum and nickel atoms and observed unusual dynamic behavior in direct space and in real time. As the two metals separate from one another while maintaining an interface, they become highly active for electrochemical water splitting, leading to efficient hydrogen evolution.