Balancing Electrons to Break the Activity‐Selectivity Trade‐Off in H ₂ O ₂ Electrosynthesis

ABSTRACT Electrochemical H 2 O 2 synthesis through the two‐electron oxygen reduction reaction (2e − ORR) is constrained by a scaling relationship linking electron concentration to *OOH adsorption, resulting in an inferior activity‐selectivity trade‐off. Here, we break this undesirable trade‐off by implementing electronic concentration balancing in CuS through the concurrent introduction of cobalt dopants and cobalt vacancies. Cobalt doping converts CuS from p‐type to n‐type, boosting electron availability and accelerating 2e − ORR kinetics. Meanwhile, cobalt vacancies withdraw excess carriers, preventing electron over‐accumulation and tuning *OOH binding to promote H 2 O 2 desorption rather than O‐O bond cleavage. The optimized catalyst delivers an excellent H 2 O 2 yield rate of 8.14 mol g −1 h −1 with >84% selectivity in a •OH quench‐prone 1.0 M KOH solution. When integrated into an electro‐Fenton system, it achieves nearly 100% degradation of rhodamine B and remains stable over more than seven cycles. This work integrates heterometal doping and vacancy engineering to balance electrochemical activity and selectivity for efficient H 2 O 2 electrosynthesis.