Recommended practice to report selectivity in electrochemical synthesis of H 2 O 2

Two different types of H2O2 selectivity are reported for the electrochemical synthesis of H2O2: molar fraction selectivity and Faradaic selectivity. Here we revisit their definitions and discuss the best way to report H2O2 selectivity, which can help to avoid misunderstandings or unfair performance comparisons in this growing field.