Nanoscale Ni(OH)_x Films on Carbon Cloth Prepared by Atomic Layer Deposition and Electrochemical Activation for Glucose Sensing

Glucose detection is a highly important technique for clinical applications. This work reports a new strategy to synthesize the efficient electrocatalyst for electrochemical glucose detection. The electrocatalyst was fabricated by using the conformal film coating technology of atomic layer deposition (ALD) for a pre-electrocatalyst of NiSx, followed by an electrochemical oxidation process to afford Ni(OH)x in alkaline. The afforded Ni(OH)x is highly rough and electrocatalytically active, and it exhibits a superior performance for the glucose sensing. The electrocatalyst material, as well as the glucose sensing conditions, is carefully optimized on flat glassy carbon electrodes, and benefiting from the conformal coating ability of ALD, the material preparation method can be well transferred for a rough high-surface-area substrate. Using high-surface-area carbon cloth (CC) as the ALD substrates and electrodes, we can boost the glucose sensitivity by over 10 times as compared to that on flat glassy carbon substrates. The glucose sensitivity of the obtained Ni(OH)x/CC electrode can achieve as high as 19.42 ± 0.07 mA mM–1 cm–2, with a decent linear response range of 0.004–0.6 mM and an LOD of 0.47 μM. The Ni(OH)x/CC electrodes are also shown of excellent fabrication reproducibility, good sensing selectivity, and good stability, which all make them highly attractive for practical sensing applications. These results highlight not only the excellent performance of the electrocatalyst for glucose detection but also the high promise of the ALD synthesis approach for fabricating electrochemical sensors in general.