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Improving the electron–hole separation efficiency and accelerating the reaction kinetics of semiconductors are effective methods for improving the photoelectric catalytic activity of TiO2. In this study, sulfur-doped TiO2 (S–TiO2) nanorod arrays grown on a fluorine-doped SnO2 transparent conductive glass were successfully prepared using a microwave-assisted method for the photoelectrochemical (PEC) biosensing of glucose. The charge separation efficiency on S–TiO2 was evaluated by subjecting the prepared material to X-ray photoelectron spectroscopy, PEC measurements, and theoretical calculations based on density functional theory. The results clearly showed that the sulfur impurity state could not only reduce the bandgap but also serve as "stairs" to facilitate the electron transfer. Sulfur atoms that were successfully doped into TiO2 significantly promote the separation of the photogenerated carriers and improve the photocatalytic activity of the photoelectrode. Consequently, excellent glucose-detection sensitivities of 54 and 19 μA mM−1 cm−2 were achieved for fragments with sizes of 0.1–1.5 and 2–12 mM, respectively. [ABSTRACT FROM AUTHOR]

• The novel porous Co 3 O 4 /N-RGO nanocomposite as gas-sensing materials derived from MOFs/RGO as templates and precursor. • Porous Co 3 O 4 concave cubes were distributed on the surface of nitrogen-doped RGO sheets to form Co 3 O 4 /N-RGO nanocomposite owned highly porous structures and large specific areas. • The synergistic effect or coupling effect between porous Co 3 O 4 and N-RGO enhance greatly the sensing performance towards ethanol vapor. • Compare with Co 3 O 4 and Co 3 O 4 /RGO, the Co 3 O 4 /N-RGO-0.5 nanocomposites as ethanol sensing materials showed lower working temperature (200 °C), higher response and shorter response-recover time. Co 3 O 4 /N-doped reduced graphene oxide (N-RGO) nanocomposite with mesoporous structure was fabricated by using metal organic frameworks (MOFs) as both template and precursor growing on RGO sheets. Porous Co 3 O 4 cubes were assembled and grown on the surface of N-RGO layers, while N was doped into RGO to form N-RGO in situ synthesis route. The effect of RGO initial concentration on structure, component and gas-sensing properties of Co 3 O 4 /N-RGO nanocomposite was studied. The gas-sensing result demonstrated that the sensor based-on Co 3 O 4 /N-RGO-0.5 (the mass of RGO was 0.5 mg) nanocomposite possessed better gas-sensing performances to ethanol, such as higher response, faster response-recovery time and lower working temperature than that of other samples. The enhanced gas-sensing properties of sensor based-on Co 3 O 4 /N-RGO-0.5 nanocomposite to ethanol could be attributed to increasing of specific surface area, coupling effect between Co 3 O 4 and nitrogen doped RGO as well as the existence of N-doping RGO which improved electron transferring of material in sensing process. Co 3 O 4 /N-RGO-0.5 nanocomposite has been proved to be a promising gas-sensing material for detecting ethanol at a low temperature. [ABSTRACT FROM AUTHOR]

In this paper, we report the fast synthesis of porous NiCo 2 O 4 hollow nanospheres via a polycrystalline Cu 2 O-templated route based on the elaborately designed “coordinating etching and precipitating” process. The composition and morphology of the porous NiCo 2 O 4 hollow nanospheres were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electron-transfer capability and electrocatalytic activity of the materials were investigated by electrochemical impedance spectroscopy and cyclic voltammetry. NiCo 2 O 4 was endowed with superior electron-transfer capability, large surface area, and abundant intrinsic redox couples of Ni 2+ /Ni 3+ and Co 2+ /Co 3+ ions; thus, the modified electrode exhibited excellent glucose-sensing properties, with a high sensitivity of 1917 μA·mM −1 ·cm −2 at a low concentration, a good linear range from 0.01 mM to 0.30 mM and from 0.30 mM to 2.24 mM, and a low detection limit of 0.6 μM ( S / N = 3). [ABSTRACT FROM AUTHOR]

The Au/ZnSe/ZnO heterojunction material with less transition zone on the two-phase interface was successfully prepared by the in-situ replacement of zinc oxide by Se2-. Moreover, the heterojunction formed by in-situ substitution can effectively reduce the interface transfer resistance and increase the life of carriers. The photocurrent of Au/ZnSe/ZnO is almost twice that of Au/ZnO, due to the formation of heterojunction ZnSe interface. As a result, the carrier lifetime of the material is increased by nearly 2.7 times (126.26 s/46.83 s) compared to Au/ZnO. Ascorbic acid is a very important compound for human metabolism, but there is no simple and rapid method to detect ascorbic acid. Au/ZnSe/ZnO is used as the photoanode of the photoelectric non-enzymatic sensor system for AA detection. The sensitivity of Au/ZnSe/ZnO/FTO-based PEC AA sensor is 113.75 μA mM−1 cm−2, exhibiting its advantages of fast, sensitive and high response. • Au/ZnSe/ZnO multi-element composite material changes the electron transport path and improves the carrier transfer. • 2. ZnSe resistance to interface recombination effectively hindered the recombination of carriers. • Enhancing the absorption of visible light, improving the carrier lifetime and forming the two-phase low interface transition zone all enhance the photoelectrochemical performance. [ABSTRACT FROM AUTHOR]