Zhi-Da Gao

Synthesis of Magnetically Separable Ag3PO4/TiO2/Fe3O4 Heterostructure with Enhanced Photocatalytic Performance under Visible Light for Photoinactivation of Bacteria

Silver orthophosphate (Ag3PO4) is a low-band-gap photocatalyst that has received considerable research interest in recent years. In this work, the magnetic Ag3PO4/TiO2/Fe3O4 heterostructured nanocomposite was synthesized. The nanocomposite was found to exhibit markedly enhanced photocatalytic activity, cycling stability, and long-term durability in the photodegradation of acid orange 7 (AO7) under visible light. Moreover, the antibacterial film prepared from Ag3PO4/TiO2/Fe3O4 nanocomposite presented excellent bactericidal activity and recyclability toward Escherichia coli (E. coli) cells under visible-light irradiation. In addition to the intrinsic cytotoxicity of silver ions, the elevated bactericidal efficiency of Ag3PO4/TiO2/Fe3O4 can be largely attributed to its highly enhanced photocatalytic activity. The photogenerated hydroxyl radicals and superoxide ions on the formed Ag/Ag3PO4/TiO2 interfaces cause considerable morphological changes in the microorganisms cells and lead to the death of the bacteria.

Signal-amplified platform for electrochemical immunosensor based on TiO2 nanotube arrays using a HRP tagged antibody-Au nanoparticles as probe.

In this study, a novel signal-amplified electrochemical immunosensor was proposed by using TiO(2) nanotube (TiNT) arrays as the platform. Due to the distinct tubular features-large surface area, high pore volume and good electrochemical conductivity, the TiNT based electrodes exhibited excellent signal-amplified effects. gold nanoparticle (AuNP) was further utilized to bind horseradish peroxidase (HRP) tagged antibodies as recognition elements. Compared to the immunosensor based on either flat electrode, the immunosensors using TiNT layer as electrode showed higher amplified electrochemical signals from the catalytic reaction of HRP relative to hydrogen peroxide (H(2)O(2)). Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to antigen in a concentration range from 0.1 ng mL(-1) to 10(5) ng mL(-1) with a detection limit of 0.01 ng mL(-1). The results showed that the TiNT-based electrochemical immunosensing platform could provide a great potential in clinical application for detection of low-abundant proteins.

Development of Amperometric Glucose Biosensor Based on Prussian Blue Functionlized TiO2 Nanotube Arrays

Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. The current work demonstrates a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode on which Prussian Blue (PB)-an “artificial enzyme peroxidase” and enzyme glucose oxidase (GOx) have been immobilized. For this, PB nanocrystals are deposited onto the nanotube wall photocatalytically using the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M−1 cm−2, and the detection limit is about 3.2 μM. These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.

Nickel Hydroxide Nanoparticle Activated Semi‐metallic TiO2 Nanotube Arrays for Non‐enzymatic Glucose Sensing

Semi-metallic TiO2 nanotube arrays (TiOx Cy NTs) have been decorated uniformly with Ni(OH)2 nanoparticles without the aid of a polymer binder. The resulting hybrid nanotube arrays exhibit excellent catalytic activity towards non-enzymatic glucose electro-oxidation. The anodic current density of the glucose oxidation is significantly improved compared with traditional TiO2 nanotubes decorated with Ni(OH)2 . Moreover, the Ni(OH)2 /TiOx Cy NT-based electrode shows a fast response, high sensitivity, wide linear range, good selectivity and stability towards glucose electro-oxidation, and thus provides a promising and cost-effective sensing platform for non-enzymatic glucose detection.

Galvanic deposition of nanostructured noble-metal films on silicon

Galvanic Deposition of Nanostructured Noble-Metal Films on Silicon Yan-Yan Song, Zhi-Da Gao, John J. Kelly,* and Xing-Hua Xia Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093, China Department of Physics, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China Debye Institute, Utrecht University, 3584 CC Utrecht, The Netherlands

Visible-Light-Triggered Drug Release from TiO2 Nanotube Arrays: A Controllable Antibacterial Platform

In this work, we use a double-layered stack of TiO2 nanotubes (TiNTs) to construct a visible-light-triggered drug delivery system. The key for visible light drug release is a hydrophobic cap on the nanotubes containing Au nanoparticles (AuNPs). The AuNPs allow for a photocatalytic scission of the hydrophobic chain under visible light. To demonstrate this principle, we loaded ampicillin (AMP) into the lower part of the TiO2 nanotube stack, triggered visible-light-induced release, and carried out antibacterial studies. The release from the platform becomes most controllable if the drug is silane-grafted in the hydrophilic bottom layer for drug storage. Thus, visible light photocatalysis can also determine the release kinetics of the active drug from the nanotube wall.

One-Step to Prepare Self-Organized Nanoporous NiO/TiO2 Layers and its Use in Non-Enzymatic Glucose Sensing

A highly ordered nanoporous NiTi oxide layers were fabricated on Ti alloys with high Ni contents (50.6 at.%) by a combination of self-organizing anodization at 0°C and subsequent selective etching in H2O2. The key for successful formation of such layers is to sufficiently suppress the dissolve of NiO by applying lower temperature during anodization. The resulting nanoporous structure is connected and well-adhered, which exhibits a much higher electrochemical cycling stability in 0.1 M NaOH. Without further surface modification or the use of polymer binders, the layers can be behave as a low-cost, stable and sensitive platform in non-enzymatic glucose sensing.

Graphitic C3N4‐Sensitized TiO2 Nanotube Layers: A Visible‐Light Activated Efficient Metal‐Free Antimicrobial Platform

Herein, we use a facile procedure to graft a thin graphitic C3N4 (g-C3N4) layer on aligned TiO2 nanotube arrays (TiNT) by a one-step chemical vapor deposition (CVD) approach. This provides a platform to enhance the visible-light response of TiO2 nanotubes for antimicrobial applications. The formed g-C3N4/TiNT binary nanocomposite exhibits excellent bactericidal efficiency against Escherichia coli (E. coli) as a visible-light activated antibacterial coating, without the use of additional bactericides.

Pt-Decorated g-C3N4/TiO2 Nanotube Arrays with Enhanced Visible-Light Photocatalytic Activity for H2 Evolution

Abstract Aligned TiO2 nanotube layers (TiNTs) grown by self‐organizing anodization of a Ti‐substrate in a fluoride‐based electrolyte were decorated with graphitic‐phase C3N4 (g‐C3N4) via a facile chemical vapor deposition approach. In comparison with classical TiO2 nanotubes (anatase), the g‐C3N4/TiNTs show an onset of the photocurrent at 2.4 eV (vs. 3.2 eV for anatase) with a considerably high photocurrent magnitude in the visible range. After further decoration with Pt nanoparticles, we obtained a visible‐light responsive platform that showed, compared with g‐C3N4‐free TiNTs, a strong enhancement for photoelectrochemical and bias‐free H2 evolution (15.62 μLh−1 cm−2), which was almost a 98‐fold increase in the H2 production rate of TiNTs (0.16 μLh−1 cm−2). In a wider context, the g‐C3N4‐combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible‐light response in photocatalytic applications.

Co3O4-doped Co/CoFe nanoparticles encapsulated in carbon shells as bifunctional electrocatalysts for rechargeable Zn–Air batteries

The development of catalysts based on non-precious metals that are able to catalyze both the oxygen reduction and oxygen evolution reactions (ORR/OER) is the key element to promote the practical application of rechargeable metal–air batteries. Here we report a novel concept that layered double hydroxides (LDHs) can be used as a precursor to form bimetals and their oxides simultaneously. Co3O4-doped Co/CoFe nanoparticles integrated with graphitic shells are derived from the thermal decomposition of a CoFe LDH bonded with urea as the carbon precursor. The composite material shows a surprisingly high bifunctional (ORR/OER) catalytic activity. The realized core–shell structure synergistically promotes the ORR performance while cobalt oxide doped on the metal surface boosts the OER performance. In addition, the carbon shell ensures high electrical conductivity and effectively impedes the aggregation and the further oxidation of Co/CoFe nanoparticles. When integrating the catalyst into a rechargeable Zn–air battery, the battery performance shows a higher discharge potential and cycling stability (over 65 h of cycling) and a lower charge plateau compared with a Zn–air battery based on a Pt/C and RuO2 catalyst mixture. This work demonstrates a new efficient air cathode material which could be practically applied to rechargeable metal–air batteries or other fuel cells.