Ni-Coated Diamond-like Carbon-Modified TiO2 Nanotube Composite Electrode for Electrocatalytic Glucose Oxidation

At a Glance

Metadata	Details
Publication Date	2022-09-08
Journal	Molecules
Authors	Yi Kang, Xuelei Ren, Yejun Li, Zhiming Yu
Institutions	Third Xiangya Hospital, Central South University
Citations	11
Analysis	Full AI Review Included

Executive Summary

This analysis details the development and performance of a highly stable, sensitive Ni-Coated Diamond-like Carbon (DLC)-Modified TiO₂ Nanotube (TNT) composite electrode designed for non-enzymatic glucose sensing.

Core Innovation: The electrode leverages the high surface area of anodized TiO₂ nanotubes as a stable scaffold, combined with a Ni-doped DLC film deposited via magnetron sputtering.
Performance Benchmark: Achieved a peak sensitivity of 1063.78 µA·mM^-1·cm^-2, significantly outperforming many comparable non-enzymatic sensors reported in the literature.
Detection Capability: Demonstrated an ultra-low detection limit (LOD) of 0.53 µM (S/N = 3), suitable for detecting trace glucose concentrations.
Synergistic Mechanism: The DLC film acts as a fixed tool, ensuring uniform dispersion and strong binding of Ni nanoparticles, which prevents aggregation and reduces electron transfer resistance, leading to enhanced catalytic activity.
Stability and Selectivity: The composite showed excellent long-term stability, retaining 82.6% of its initial current response after one month, and demonstrated strong anti-interference capabilities against common biological species (DA, UA, AA, galactose).
Preparation Method: The composite was fabricated using a scalable, three-step process: anodic oxidation (TNTs), pulsed electrodeposition (Ni), and radio frequency (RF) bias-assisted magnetron sputtering (Ni-DLC).

Technical Specifications

Parameter	Value	Unit	Context
Peak Sensitivity (Low Conc.)	1063.78	µA·mM^-1·cm^-2	Linear range: 0.99 mM to 3.00 mM
Sensitivity (High Conc.)	554.89	µA·mM^-1·cm^-2	Linear range: 3.00 mM to 22.97 mM
Detection Limit (LOD)	0.53	µM	Calculated at S/N = 3
Long-Term Stability	82.6	%	Current response retained after 1 month
Ni Atomic Ratio (DLC/TNTs)	6.13	%	Measured by EDX after sputtering
Ti Nanotube Diameter	less than 100	nm	Morphology of TNT substrate
Applied Potential (Chronoamperometry)	0.55	V	Used for glucose oxidation testing
CV Scan Rate Range	10 - 150	mV/s	Used for mass transfer analysis
Ni/TNT Electrocatalytic Current	0.07	mA	Measured in 0.5 M NaOH + 1 mM glucose
Ni-DLC/TNT Electrocatalytic Current	0.21	mA	Measured in 0.5 M NaOH + 1 mM glucose
Time to Stable Current Response	5	s	Response time for glucose oxidation

Key Methodologies

The Ni-DLC/TNT composite electrode was prepared using a sequential three-step fabrication process on a polished Ti sheet (5 x 5 x 1.5 mm).

TiO₂ Nanotube Array (TNT) Formation (Anodic Oxidation):
- Substrate: Polished Ti sheet (anode).
- Electrolyte: Glycerol solution containing 0.2-7 M NH₄F.
- Voltage/Time: 25 V for 1 hour.
Ni Nanoparticle Deposition (Pulsed Electrodeposition):
- System: Three-electrode system (TNT working electrode, Ni sheet counter electrode).
- Electrolyte: 300 g/L NiSO₄·6H₂O, 45 g/L NiCl₂·6H₂O, and 37 g/L H₃BO₃.
- Temperature: 38 °C.
- Pulse Parameters:
  - Cathode Pulse: -160 mA/cm² for 8 ms.
  - Anode Pulse: +160 mA/cm² for 2 ms.
  - Current Turn-off Time: 1000 ms.
- Total Time: 10 minutes.
Ni-DLC Film Deposition (RF Bias-Assisted Magnetron Sputtering):
- Process: Sputtering Ni-doped DLC onto the Ni/TNT surface.
- Gas Flow Ratio (Ar:C₂H₂): 16:6 sccm.
- Deposition Pressure: 1.0 Pa.
- RF Power: 200 W.
- Bias Voltage: 25 V.
- Sputtering Time: 5 minutes.

Commercial Applications

The robust, high-performance Ni-DLC/TNT composite material system has direct relevance across several high-tech sectors, particularly those requiring stable electrocatalytic surfaces and advanced thin-film coatings.

Continuous Glucose Monitoring (CGM):
- Provides a highly stable and sensitive non-enzymatic platform, ideal for long-term, implantable sensors used in diabetes management.
- The DLC coating offers superior biocompatibility and corrosion resistance compared to bare metal electrodes.
Advanced Biosensing and Diagnostics:
- The high selectivity and low LOD make the electrode suitable for detecting other trace biological analytes in complex media.
- Applicable in point-of-care testing (POCT) devices where stability and resistance to fouling are critical.
Electrocatalysis and Energy Storage:
- The Ni-DLC/TNT structure—a metal catalyst fixed within a carbon matrix on a high surface area oxide scaffold—is a promising architecture for various electrochemical reactions, including water splitting (OER/HER) and methanol oxidation.
- The ordered TNT structure enhances ion diffusion and charge transfer kinetics.
Protective and Functional Coatings:
- The DLC film, known for its hardness and chemical inertness, can be adapted for protective coatings on biomedical devices or industrial components operating in harsh, corrosive environments.
- The ability to dope DLC with metals (Ni) via sputtering allows for tuning of electrical conductivity and catalytic properties.

View Original Abstract

In this paper, a Ni and diamond-like carbon (DLC)-modified TiO2 nanotube composite electrode was prepared as a glucose sensor using a combination of an anodizing process, electrodeposition, and magnetron sputtering. The composition and morphology of the electrodes were analyzed by a scanning electron microscope and energy dispersive X-ray detector, and the electrochemical glucose oxidation performance of the electrodes was evaluated by cyclic voltammetry and chronoamperometry. The results show that the Ni-coated DLC-modified TiO2 electrode has better electrocatalytic oxidation performance for glucose than pure TiO2 and electrodeposited Ni on a TiO2 electrode, which can be attributed to the synergistic effect between Ni and carbon. The glucose test results indicate a good linear correlation in a glucose concentration range of 0.99-22.97 mM, with a sensitivity of 1063.78 μA·mM−1·cm−2 and a detection limit of 0.53 μM. The results suggest that the obtained Ni-DLC/TiO2 electrode has great application potential in the field of non-enzymatic glucose sensors.

Tech Support

Original Source

DOI: https://doi.org/10.3390/molecules27185815

References

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