A Photoelectrochemical Sensor Based on Anodic TiO2 for Glucose Determination

Abstract

A simple photoelectrochemical (PEC) sensor based on non-modified nanostructured anodic TiO2 was fabricated and used for a rapid and sensitive detection of glucose. The anodic TiO2 layers were synthesized in an ethylene glycol-based solution containing NH4F (0.38 wt.%) and H2O (1.79 wt.%) via a three-step procedure carried out at the constant voltage of 40 V at 20 °C. At the applied potentials of 0.2, 0.5, and 1 V vs. saturated calomel electrode (SCE), the developed sensor exhibited a photoelectochemical response toward the oxidation of glucose, and two linear ranges in calibration plots were observed. The highest sensitivity of 0.237 µA µmol−1 cm−2 was estimated for the applied bias of 1 V. The lowest limit of detection (LOD) was obtained for the potential of 0.5 V vs. SCE (7.8 mM) with the fastest response at ~3 s. Moreover, the proposed PEC sensor exhibited relatively high sensibility, good reproducibility, and due to its self-cleaning properties, a good long-term stability. Interfering tests showed the selective response of the sensor in the presence of urea and uric acid. Real-life sample analyses were performed using an intravenous glucose solution, which confirmed the possibility of determining the concentration of analyte in such types of samples.

Plasmonic Au–Pd Bimetallic Nanocatalysts for Hot-Carrier-Enhanced Photocatalytic and Electrochemical Ethanol Oxidation

“…Anodic (positive) spikes in photocurrent indicated accumulation of charge at the electrode-electrolyte interface, while cathodic (negative) transients are indicative of charge recombination. Lack of photocurrent transients indicated unimpeded charge transfer from the electrode to the electrolyte, thereby hole transfer was facilitated at the catalyst surface for EOR [55][56][57]. Average peak EOR photocurrent densities generated under AM1.5G irradiation on TiO2 in Figure 8a were 1.31 μA cm −2 for Au, 1.31 μA cm −2 for Au0.9Pd0.1, 1.43 μA cm −2 for AuCore-AuPdShell, and 1.97 μA cm −2 for AuCore-PdShell.…”

“…The increase in photocurrent was attributed to interband excitations that initiated injection of d-band holes from the Au into the Pd active sites for subsequent reaction with adsorbed species [59]. Slow relaxation of the photocurrent after the "light on" step for AuPd alloy indicated accumulation of holes at the electrode-electrolyte interface, facilitated favorable reaction kinetics, and hindered charge recombination [55][56][57]. In comparison, catalytic Pd on TiO2 generated 4.74 μA cm −2 and retained 84% of its initial photocurrent after 1900 s owing to Pd acting as a hole scavenger, which improved charge separation at the metal-semiconductor interface.…”

Photoelectrochemical Performance of Nanotubular Fe2O3–TiO2 Electrodes under Solar Radiation

“…Comparing the impregnated sample with that electrodeposited for 180 s, it is evident that the steady-state current conditions are gained within the time scale of ‘light on’ cycles for the impregnated sample, while the recombination of photogenerated charge carriers is observed during ‘light on’ cycles for the samples with a higher Fe content [ 45 ]. Additionally, for the sample electrodeposited for 180 s, characteristic cathodic current spikes appear when the light is turned off [ 46 ].…”

Functionalization of 2D MoS2 Nanosheets with Various Metal and Metal Oxide Nanostructures: Their Properties and Application in Electrochemical Sensors

“…The photo-to-current conversion results from the electron excitation and subsequent charge transfer of a material after absorbing photons [ 172 , 226 ]. The total separation of the source of excitation (light) and detection signal (photocurrent) enables this method to have the advantages of a low background signal and high sensitivity to recognize target analytes in complex samples as opposed to traditional optical methods [ 174 , 227 ]. Photoactive materials play critical roles in PEC systems; The PEC sensor output depends on the properties of these materials since they can influence the sensitivity and selectivity of the PEC sensor.…”