Electrochemical biosensors are essential for health monitors to help in diagnosis and detection of diseases. Enzyme adsorptions on biosensor electrodes and direct electron transfer between them have been recognized as key factors to affect biosensor performance. TiO2 has a good protein adsorption ability and facilitates having more enzyme adsorption and better electron transfer. In this work, Mg ions are introduced into TiO2 nanodots in order to further improve electrode performance because Mg ions are considered to have good affinity with proteins or enzymes. Mg doped TiO2 nanodots on Ti substrates were prepared by spin-coating and calcining. The effects of Mg doping on the nanodots morphology and performance of the electrodes were investigated. The density and size of TiO2 nanodots were obviously changed with Mg doping. The sensitivity of 2% Mg doped TiO2 nanodots based biosensor electrode increased to 1377.64 from 897.8 µA mM−1 cm−2 and its decreases to 0.83 from 1.27 mM, implying that the enzyme achieves higher catalytic efficiency due to better affinity of the enzyme with the Mg doped TiO2. The present work could provide an alternative to improve biosensor performances.
Xiao Li,Jiayuan Yu,Guixiang Li,Hui Liu,Aili Wang,Linjing Yang,Weijia Zhou,Benli Chu,Shengwei Liu
Constructing hierarchical structure is an effective approach to improve the activities of catalysts. Herein, a novel hierarchical structure of TiO 2 nanodots anchored on N-doped carbon nanotubes encapsulated Co nanoparticles (TiO 2 /Co@NCT) was synthesized by a simple pyrolysis method. Their catalytic performances were examined in the oxidative and light-assisted degradation of recalcitrant pollutants in the presence of the peroxymonosulfate (PMS). The Orange II removal efficiency within 15 min reached about 98.48% in TiO 2 /Co@NCT/PMS system. In this system, Co 0 is used to react with PMS to generate free radicals for the degradation of dyes. The carbon shell benefits the adsorption of dyes and prevents the catalysts from dissolving in the solution. Besides, under light irradiation, TiO 2 nanodots can be excited to generate photo-induced electrons, which can reduce inner Co 2+ to Co 0 in the degradation process, thus TiO 2 /Co@NCT exhabited high activity and outstanding stability in degradation process. The as-prepared TiO 2 /Co@NCT catalyst showed efficient degradation and superior stability, which would make it a great promise in practical applications for sewage treatment.
Photocatalytic H 2 evolution from water splitting requires an efficient photocatalyst with excellent charge separation ability and broad visible-light adsorption region. 0D CdS-TiO 2 nanodots (NDs) were successfully decorated on the 2D g-C 3 N 4 sheets via an epitaxial growth process. The as-synthesized ternary composite of CdS-TiO 2 @g-C 3 N 4 exhibits enhanced visible-light-driven photocatalytic H 2 evolution activity, as compared to the binary composites and their single components, which is about 6.7 and 11.2 times higher than those of single CdS and g-C 3 N 4 , respectively. Moreover, the as-obtained ternary composite has an external quantum efficiency (EQE) of 11.9% at 420 nm, implying the high utilization efficiency of photo-induced charges. In addition, the superior photostability can be achieved by this coupling method. The enhanced photocatalytic activity was attributed to the efficient charge separation originated from the three-level electron transfer system, the matched energy level positions, the abundant adsorption sites and active sites (0D/2D structure) and the synergistic effect among CdS, TiO 2 and g-C 3 N 4 . The work present here demonstrated that the construction of this three-level electron transfer system is an effective strategy to design more efficient ternary materials toward solar energy conversion (like H 2 production and CO 2 reduction).
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