High-Fidelity Electrochemistry with Ultraclean Graphene Electrodes

The electrochemical performance of CVD graphene electrodes has remained inconsistent and often inferior to that of exfoliated graphene, limiting their utility in analytical applications. This variability is widely attributed to structural disorder, but the dominant source remains unclear. Here, we show that amorphous carbon contamination introduced during synthesis is the primary factor governing the electrochemical behavior of CVD graphene. By eliminating this disorder during growth through oxygen-free CVD (OF-CVD), we obtain graphene electrodes that exhibit intrinsic and highly reproducible electrochemical behavior. Compared with conventional and commercial graphene, these electrodes display substantially enhanced heterogeneous electron-transfer kinetics, reduced charge-transfer resistance, and improved detection limits across both outer- and inner-sphere redox systems. Notably, they exhibit consistent anodic peak potentials across wide concentration ranges, nearly eliminating the concentration-dependent potential shifts characteristic of both glassy carbon and commercial/contaminated graphene electrodes. Further, microelectrode array architectures fabricated from this material suppress non-Faradaic background currents and exhibit steady-state diffusion behavior consistent with electrochemical theory, with improved signal-to-noise ratios. Together, these results establish that extrinsic carbon disorder has limited the electrochemical performance of CVD graphene to date. The removal of amorphous carbon reveals defect-free graphene's intrinsic electrochemical behavior and enables a reproducible, high-performance electrode platform, providing a clear pathway for reliable graphene-based electrochemical systems.