Finite Proton-Driven Self-Limiting Assembly of Nanosheets Enables Macroscopically Continuous Monolayer Films

Abstract Marcus–Hush theory dictates that heterogeneous electron transfer (HET) rates decay exponentially with distance, rendering thick electrochemical interfaces prone to high overpotentials and low Faradaic currents. Although a continuous active monolayer represents the theoretical optimum for interfacial HET, achieving such atomic-scale precision in nanosheet assembly remains a challenge. Herein, we reported a finite proton-driven self-limiting assembly strategy that enables precise atomic-thickness control. As a result, a graphene oxide monolayer (GO-ML) with 94.90% continuous coverage was successfully assembled on a macroscopic graphene film electrode. The GO-ML electrodes effectively narrow the transport bandgap to 2.07 eV and enhance the apparent standard HET rate by 44.9-fold relative to the pristine graphene film electrodes. Guided by a thermodynamic energy-level phase diagram, the obtained GO-ML electrodes achieve a submicromolar limit of detection (0.078 μM) for uric acid and a wide detection range (0–5000 μM), accommodating diverse physiological environments including sweat and urine. Furthermore, the GO-ML electrodes exhibit robust durability and wearability when integrated with a wireless communication system.