Enhanced Electrocatalytic Activity and Ultrasensitive Enzyme-Free Glucose Sensing Based on Heterogeneous Co(OH)₂ Nanosheets/CuO Microcoral Arrays via Interface Engineering

Abstract

The rational construction of semiconductor nanoheterostructures is a feasible strategy to modulate electronic structure and increase active area of the electrocatalysts for biosensing. Herein, we develop an in situ approach, electrochemical (EC−) rebuilding of the smooth Cu surface, to construct hierarchical Co(OH) 2 nanosheets/CuO microcoral arrays (Co-(OH) 2 NSs/CuO MCAs). Through engineering the heterostructures by optimizing EC-rebuilding time, the electrocatalytic activity is significantly enhanced with a higher current density of glucose oxidation. The incorporation of Co(OH) 2 NSs into CuO MCAs also leads to a large active surface area and benefits surface/ interface reactions and mass transport for shorter response for glucose oxidation, higher current density, and better selectivity for glucose sensing. Both photoelectron spectra and density functional theory (DFT) calculations prove that interface charge transfers from CuO to Co(OH) 2 , resulting in electron redistribution and a significant increase in the adsorption energy of glucose. Compared with recently reported enzyme-free glucose sensors, the fabricated Co(OH) 2 NSs/CuO MCAs electrode exhibits excellent performance for enzyme-free glucose-sensing in alkaline electrolytes with a short response time (3 s), wide linear range of 500 nM to 2.311 mM, ultrasensitivity of 2269 mA mM −1 cm −2 , low limit of detection (LOD, 378 nM), and favorable reproducibility and stability. Noticeably, the outstanding response time, favorable ultrasensitivity, and great LOD are achieved in the glucose sensing. Therefore, the proposed sensor can be used for accurate quantification of glucose concentration in human serum with good repeatability, which will provide a new platform based low-cost semiconductor nano-heterostructures for rapid diagnostic tests and health monitoring.

Tracking Atomic Diffusion in Surface and Bulk CuO via Neural Network-Based Molecular Dynamics

“…In this sense, there is an urgent need to understand the atomic diffusion mechanism during CLOU. Moreover, the atomic diffusion property of CuO plays an essential role in its application in catalysis, gas sensors, solar cells, and anode material of Li ion batteries. − Numerous early experimental works have been conducted to explore the atom diffusion features of copper oxides. , Wagner proposed that oxidation of Cu to Cu 2 O can be understood as a result of the outward diffusion of Cu atoms through the vacancy mechanism. , It is generally accepted that at high oxygen pressure, i.e., near or above the Cu 2 O/CuO equilibrium pressure at a given temperature, the diffusion in Cu 2 O is dominated by neutral or singly charged copper vacancies, while at low oxygen pressure, i.e., near or equal to the Cu/Cu 2 O equilibrium pressure at a given temperature, the diffusion in Cu 2 O is dominated by copper interstitials or oxygen vacancies. − Lately, Goldstein et al performed experiments of oxidation of Cu to Cu 2 O and CuO at 500–800 °C and atmospheric pressure . Through modeling, the authors proposed that the major defects in CuO are doubly charged Cu vacancies.…”