A Temperature-Robust Non-Enzymatic Lactate Sensor Based on Graphene Fiber Composite Electrodes

Real-time lactate monitoring is essential for clinical diagnostics, sports physiology, and industrial bioprocessing, yet conventional enzymatic sensors suffer from limited stability, narrow operational temperature range, and complex fabrication protocols. Herein, we report a robust non-enzymatic electrochemical sensor based on graphene fibers (GFs), featuring a GF/Au/Ni(OH)₂ composite electrode with controllable structure fabricated via sequential electrodeposition. Systematic optimization of deposition parameters established a quantitative relationship between surface architecture and electrochemical response, revealing a critical trade-off between active site density and charge transport efficiency. The sensor achieved optimal performance when both Au and Ni(OH)₂ were deposited for 900 s, exhibiting a high sensitivity of 1.24 mA mM⁻¹ cm⁻² and a remarkably broad operational temperature range of 0–100 °C. Moreover, the sensor demonstrates excellent repeatability, superior anti-interference capability against common electroactive species, and outstanding long-term durability with 97.8% response retention after 14 days. This work provides a rational design strategy for balancing catalytic activity and transport properties in metal–metal oxide composites, offering a reliable platform for advanced applications in next-generation wearable health-monitoring systems.