Hemin Modified TiO₂Nanoparticles with Enhanced Photoelectrocatalytic Activity for Electrochemical and Photoelectrochemical Sensing

Abstract

Hemin-functionalized TiO 2 nanoparticles were prepared and assembled on glassy carbon electrode through the electrostatic attraction between positively charged poly(diallyldimethylammonium chloride) and negatively charged hemin and TiO 2 . The scanning electron microscopy and X-ray diffraction characterization showed that the assembled hemin-TiO 2 film displayed a mesoporous structure comprising plenty of TiO 2 nanoparticles in rutile phase. The Fourier transform infrared spectra and UV-visible diffuse reflectance spectra indicated that hemin was successfully incorporated into TiO 2 film and significantly enhanced the absorption of TiO 2 film to visible light. The hemin-TiO 2 film exhibited a pair of well-defined redox peaks of hemin by cyclic voltammetry, which could effectively catalyze the electroreduction of H 2 O 2 . Thus, the hemin-TiO 2 modified electrode was employed as an electrochemical sensor for H 2 O 2 determination, showing a sensitive response linearly proportional to the concentration of H 2 O 2 from 3.0 × 10 −7 to 4.7 × 10 −4 mol · L −1 . At the same time, the photoelectrocatalytic activity of TiO 2 under visible light illumination was dramatically promoted by hemin. The hemin-TiO 2 modified electrode produced a photoelectrochemical response linearly proportional to hydroquinone in the concentration range from 4. Hemin is an iron-containing porphyrin, namely protoporphyrin IX Fe(III) complex, which is well-known as the active center of the hemeprotein family. Because of the reversible reaction of Fe(III)/Fe(II) redox couple, hemin has been extensively demonstrated as an efficient electrocatalyst for many small molecules such as hydrogen peroxide, 1-3 oxygen, 4 nitrite, 5 L-tyrosine 6 and artemisinin. 7 Generally, hemin is loaded on some supporting materials to avoid the molecular aggregation of hemin molecules in aqueous solution and improve the stability and activity of catalyst.8 On the other hand, hemin is a structural analogue of chlorophyll, which can serve as a promising photosensitizer for TiO 2 photocatalyst to harvest visible light. 9,10 Moreover, the presence of Fe(III) porphyrin ring on the surface of TiO 2 can reduce the electron-hole recombination rate and act as a mediator for continuous production of enriched concentration of hydroxyl radicals to enhance the photocatalytic activity of TiO 2 . 11TiO 2 is the most intensively studied photocatalyst for degradation of various organic pollutants.12 In recent years, TiO 2 nanomaterials have been widely utilized for fabrication of sensing devices because of their fascinating properties such as large surface area, good biocompatibility, high stability, and unique electronic and photocatalytic performances.13 When catalytic materials including metal nanoparticles, small molecules and biological macromolecules are immobilized on nanostructured TiO 2 , the obtained nanocomposites can act as bifunctional catalysts which not only possess the catalytic activity of introduced materials but also preserve the intrinsic photocatalytic capacity of T...

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“…In order to overcome these obstacles, non‐enzymatic H 2 O 2 electrochemical sensors have been described over the past few years. Various nanocomposites with peroxidase‐like activity, including noble metal nanocomposites , metal oxide nanostructures , metalloporphyrins and their derivatives were developed as non‐enzymatic H 2 O 2 sensors.…”

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“…Others photoelectrochemical sensors based on CdS/graphene‐DNA and CdSe were also proposed for catechol and p‐nitrophenol determination, respectively. The results presented in all the studies were quite satisfactory, mainly concerning the limits of detection determined, which were in many cases lower than those observed by conventional electrochemical methods . Thus, it is noteworth that there is still much to be explored in field of photoelectrochemical sensors, since there are a range of photoactive materials to be explored.…”

“…The increase of the sensitivity of a sensor is extremely important, especially for detection of molecules at very low concentration levels in the samples to be analyzed. As result, the PECs are nowadays one of the most attractive sensor‐based principles for analytical applications .…”

“…The increase of the sensitivity of a sensor is extremely important, especially for detection of molecules at very low concentration levels in the samples to be analyzed. As result, the PECs are nowadays 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 one of the most attractive sensor-based principles for analytical applications [22][23][24][25][26][27][28].…”

“…Therefore, a num-ber of photoactive materials based on TiO 2 combined to other inorganic semiconductors [33] and organic dyes compounds [34][35][36][37][38][39] have been proposed. For example, Zhang et al, developed photoelectrochemical sensors employing TiO 2 sensitized with Hemin [25] and CdSe-DNA [26]. The hemin-TiO 2 modified electrode was employed for the determination of H 2 O 2 and hydroquinone with linear response range of 3.0 3 10 À7 -4.7 3 10 À4 mol L À1 and from 4.0 3 10 À7 to 3.0 3 10 À5 mol L À1 , respectively.…”