Engineering valence state of Co3O4 on carbon cloth for efficient nonenzymatic glucose detection

Regulating the cobalt valence state is a crucial strategy for enhancing nonenzymatic glucose detection. In this study, two self-supported Co 3 O 4 nanocomposites were fabricated on plasma-pretreated carbon cloth (CC P ) by electrodepositing an α-Co(OH) 2 precursor followed by either plasma treatment yielding Co 3 O 4 /CC P -P or calcination yielding Co 3 O 4 /CC P -C. Structural characterization reveals that plasma pretreatment enriches the CC P surface with abundant oxygen-containing functional groups (OCGs), significantly improving its hydrophilicity. In addition, the Co 3 O 4 /CC P -C exhibits a phase-pure structure enriched with multiple Co 3+ and surface-adsorbed oxygen (O Ads ). These properties coupled with its rapid electron-transfer capability significantly promote the glucose oxidation reaction. Compared with Co 3 O 4 /CC P -P, the Co 3 O 4 /CC P -C electrode presents markedly higher electrocatalytic activity toward glucose oxidation, featuring superior sensitivities of 6380 μA·mM −1 ·cm −2 (0.05–0.4 mM) and 2070 μA·mM −1 ·cm −2 (0.4–1.4 mM), along with a lower limit of detection (2.9 μM). The Co 3 O 4 /CC P -C electrode also exhibits excellent selectivity, good preparation repeatability (relative standard deviation (RSD) = 2.14%), operational repeatability (RSD = 1.36%) and favorable stability (RSD = 2.40%). This study provides a promising approach for developing efficient non-enzymatic glucose oxidation Co-based electrocatalysts, and gets insights into the influence mechanism by engineering the Co valence state.