Hydrogen, derived from polymer electrolyte fuel cells (PEFCs), is an excellent source of clean energy. However, PEFCs require platinum (Pt), which is a limited resource. Some studies have shown that Pt nanoclusters (NCs) have higher activity than conventionally used Pt nanoparticles, however the origin of their higher activity is unclear. Now, researchers have synthesized a novel Pt NC catalyst with unprecedented activity and identified the reason for its high performance.