Breaking the Unity Limit: Electrocatalytic Systems Surpassing 100% Faradaic Efficiency

ABSTRACT Recent advancements in electrocatalytic systems have revealed apparent system‐level Faradaic efficiencies ( ) exceeding 100% when normalized to the external charge input ( Q _external ), challenging the conventional assumption that each externally injected electron is associated with a single product‐forming event at a single interface. Such > 100% values do not violate charge or energy conservation; rather, they reflect unconventional electron utilization enabled by reactor design, interfacial modulation, and transport control under a fixed Q _external . This Review establishes a unified system‐level electron‐accounting framework and categorizes. > 100% reports into four mechanistic pathways: (1) dual‐electrode synergistic production through bidirectional product formation; (2) dynamic interfacial reconstruction that enhances multichannel electron activation; (3) nonequilibrium charge transport across spatial and potential gradients; and (4) intermediate‐sharing mechanisms facilitated by membranes or interface coupling. Representative systems are examined to illustrate how efficiencies exceeding unity with respect to Q _external arise from physical mechanisms rather than measurement artifacts. Furthermore, we critically assess key validation methodologies and discuss persistent challenges in reaction standardization, electrode stability, energy efficiency, and reactor scalability. Overall, this Review provides a mechanistic and structural foundation for interpreting and engineering next‐generation multi‐pathway electrocatalytic platforms while fully respecting thermodynamic and conservation limits.