Electrocatalytic Applications of Graphene–Metal Oxide Nanohybrid Materials

Development of state-of-the-art electrocatalysts using commercially available precursors with low cost is an essential step in the advancement of next-generation electrochemical energy storage/conversion systems. In this regard, noble metal-free and graphene-supported nanocomposites are of particular interest. Graphene-based nanocomposite is an excellent candidate as energy-device and sensor-related electrode materials, largely due to their high electrical conductivity, large specific surface area, high-speed electron/heat mobility, and reasonably good mechanical strength. Among many types of graphene-based composite materials, graphene–metal oxide nanohybrids hold great promise toward engineering efficient electrocatalysts and have attracted increasing interest in both scientific communities and industrial partners around the world. The goal of this chapter is primarily set on an overview of cutting-edge developments in graphene–metal oxide nanohybrid materials, with the recently reported results from worldwide research groups. This chapter is presented first with an introduction, followed by synthetic methods and structural characterization of nanocomposites, an emphasis on their applications in energy and sensor-related fields, and finally completed with brief conclusions and outlook

Design, Assembly, and Fabrication of Two-Dimensional Nanomaterials into Functional Biomimetic Device Systems

Diverse functioning biosystems in nature have inspired us and offered unique opportunities in developing novel concepts as well as new class of materials and devices. The design of bioinspired functional materials with tailored properties for actuation, sensing, electronics, and communication has enabled synthetic devices to mimic natural behavior. Among which, artificial muscle and electronic skin that enable to sense and respond to various environmental stimuli in a human-like way have been widely recognized as a significant step toward robotics applications. Polymer materials have previously been dominant in fabricating such functional biomimetic devices owing to their soft nature. However, lacking multifunctionality, handling difficulty, and other setbacks have limited their practical applications. Recently, versatile and high-performance two-dimensional (2D) materials such as graphene and its derivatives have been studied and proven as promising alternatives in this area. In this chapter, we highlight the recent efforts on fabrication and assembly of 2D nanomaterials into functional biomimetic systems. We discuss the structure-function relationships for the development of 2D materials–based biomimetic devices, their tailoring property features, and their variety of applications. We start with a brief introduction of artificial functional biomimetic materials and devices, then summarize some key 2D materials–based systems, including their fabrication, properties, advantages and demonstrations, and finally present concluding remarks and outlook

Facile synthesis of chitosan-capped ZnS quantum dots as an eco-friendly fluorescence sensor for rapid determination of bisphenol A in water and plastic samples

This paper describes a novel eco-friendly fluorescence sensor for determination of bisphenol A (BPA) based on chitosan-capped ZnS quantum dots (QDs). By using safe and inexpensive materials, nontoxic ZnS QDs were synthesized via an environment-friendly method using chitosan as a capping agent. The as-prepared ZnS QDs exhibited characteristic absorption (absorbance edge at 310 nm) and emission (maxima at 430 nm) spectra with a relatively high fluorescence quantum yield of 11.8%. Quantitative detection of BPA was developed based on fluorescence quenching of chitosan-capped ZnS QDs with high sensitivity and selectivity. Under optimal conditions, the fluorescence response of ZnS QDs was linearly proportional to BPA concentration over a wide range from 0.50 to 300 mu g L-1 with a detection limit of 0.08 mu g L-1. Most of the potentially coexisting substances did not interfere with the BPA-induced quenching effect. The proposed analytical method for BPA was successfully applied to water and plastic real samples. The possible quenching mechanism is also discussed

Graphene-Paper Based Electrochemical Sensors

Graphene paper as a new form of graphene-supported nanomaterials has received worldwide attention since its first report in 2007. Due to their high flexibility, lightweight and good electrical conductivity, graphene papers have demonstrated the promising potential for crucial applications in electrochemical sensors and energy technologies among others. In this chapter, we present some examples to overview recent advances in the research and development of two-dimensional (2D) graphene papers as new materials for electrochemical sensors. The chapter covers the design, fabrication, functionalization and application evaluations of graphene papers. We first summarize the mainstream methods for fabrication of graphene papers/membranes, with the focus on chemical vapour deposition techniques and solution-processing assembly approaches. A large portion of this chapter is then devoted to the highlights of specific functionalization of graphene papers with polymer and nanoscale functional building blocks for electrochemical-sensing purposes. In terms of electrochemical-sensing applications, the emphasis is on enzyme-graphene and nanoparticle-graphene paper-based systems for the detection of glucose. We finally conclude this chapter with brief remarks and outlook