The important ingredient in your catalyst you never meant to add

Nature Catalysis, Published online: 07 August 2026; doi:10.1038/s41929-026-01596-7 Impurities are usually blamed for irreproducible catalysis, but what if, in electrochemistry, they are part of the active material? It is now shown that, in CO2 electroreduction on oxide-derived copper, an uninvited ingredient from a standard bicarbonate electrolyte, Na+, can be incorporated into nanoscale, defect-rich microstructures during the oxide-to-metal transformation. This incorporation tracks with enhanced CO2 reduction activity, suggesting that trace electrolyte ions can become an integral (and previously hidden) part of the catalyst’s working state.