Co3O4/ZnO/CNTs Photoelectrochemical Sensor for Sensitive and Selective LA Detection

As an intermediate product of an important biological tumor marker, lactic acid (LA) seriously affects human health and athlete body assessment, and the sensitivity detection of LA in human fluids is crucial. In this work, Co$_{\text{3}}$O$_{\text{4}}$/ZnO/CNTs electrodes were prepared by simple hydrothermal and annealing methods, and the electrode materials and photoelectrochemical (PEC) properties were systematically characterized and tested. In the simulated sweat samples, the Co$_{\text{3}}$O$_{\text{4}}$/ZnO/CNTs electrodes had a linear relationship with the LA concentration in the range of 0.1-100$\mu $m, with a linear correlation coefficient of 0.995 and high sensitivity and low detection limits, respectively, of 165.8$\mu $AmM$^{\text{-1}}$cm$^{\text{-2}}$and 0.01$\mu $m, respectively. The electrode opens up new frontiers for enzyme-free, noninvasive, and real-time monitoring.