Ultra-fine nickel sulfide nanoclusters @ nickel sulfide microsphere as enzyme-free electrode materials for sensitive detection of lactic acid

Abstract

Abstract A new facile fabrication of ultrafine nanoclusters of nickel-sulfides with an average diameter of ~3.4 nm on NiS microsphere (NiS-NC@NiS-MS) on bare nickel foam (NiF) substrate (designated as NiS-NC@NiS-MS/NiF) using one-step electrochemical strategy for the direct electrochemical oxidation and sensing of lactic acid (LA) is demonstrated. The dimension, surface morphology, crystalline nature, chemical composition, and electrochemical characteristics of the NiS Nanoclusters @ NiS Microsphere are systematically studied with field-emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HR-TEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetric measurements. The developed NiS-NC@NiS-MS/NiF electrode exhibits an excellent enzyme-mimic electrocatalytic activity towards the lactic acid oxidation at the less positive potential of ~0.45 V (vs Ag/AgCl)) and high catalytic anodic current of ~1.7 mA. The present enzyme-mimic NiS-NC@NiS-MS catalyst based sensor presents an experimental lowest detection limit of 0.5 μM, high sensitivity of 0.39 μA μM−1 with a rapid sensing response, and a linear range from 0.5 μM to 85.5 μM. Owing to the uniform and high dispersion of small NiS nanoclusters, abundant electrochemical active sites, and improved mass-transfer kinetics, the NiS-NC@NiS-MS/NiF electrode delivers a high performance lactic acid sensing. The developed non-enzymatic lactic acid biosensor based on NiS nanoclusters shows an outstanding anti-interference ability in the presence of various potential interferences (uric acid (UA), ascorbic acid (AA), paracetamol (PA), Mg2+, Na+ and Ca2+), good reproducibility, and long-term durability. Moreover, the present sensor is successfully tested the lactic acid sensing in practical human urine samples.