Oxygen vacancies on Nb 2 O 5 enhanced the performance of H 2 O 2 electrosynthesis from O 2 reduction.

A serial oxygen vacancy (O V ) on Nb 2 O 5 is synthesised by H 2 calcination, and H-300 exhibited high selectivity and activity for H 2 O 2 (93.4%, 562.5 mmol g cat -1 ). A volcano relationship is identified between the O V content and performance, which provides an attractive insight into designing electrocatalysts.