Defects engineered 2D ultrathin cobalt hydroxide nanosheets as highly efficient electrocatalyst for non-enzymatic electrochemical sensing of glucose and l-cysteine

Engineering of nanomaterials with atomic defects has becoming an effective way to boost the sensitivity of the electrochemical biosensors but challenging. Herein, a rational, facile and in-situ strategy has been reported to obtain cobalt hydroxide nanosheets (VCo-Co(OH)2) with abundant cobalt vacancies. The cobalt defects greatly enriched electroactive sites and charge transfer rates, thereby delivered excellent electrocatalytic oxidation performance towards glucose and l-cysteine. The dynamic range and low limit of detection of glucose at VCo-Co(OH)2 electrodes were found as 0.4 μM–8.23 mM and 295 nM respectively. Besides, VCo-Co(OH)2 electrodes accurately sensed the l-cysteine with lowest detection limit (76.5 nM), and broad linear sensing range (200 nM-1.94 mM), which are better than the performance of defect-free Co(OH)2 electrodes, evidence that construction of cobalt vacancy significantly boosted the electrocatalysis. Importantly, fabricated sensors had excellent interference immunity against the many biomolecules, owns good stability and reproducibility. Present work not only proposed a novel and simplistic approach to prepare the metal hydroxides with copious metal cation vacancies for electrocatalysis but also provides economical, precise, high-sensitive and disposable biosensors for clinical analysis glucose and l-cysteine.