A primary battery-on-a-chip using monolayer graphene

We present here a bottom-up approach for realizing on-chip on-demand batteries starting out with chemical vapor deposition-grown graphene. Single graphene monolayers contacted by electrode lines on a silicon chip serve as electrodes. The anode and cathode are realized by electrodeposition of zinc and copper respectively onto graphene, leading to the realization of a miniature graphene-based Daniell cell on a chip. The electrolyte is housed partly in a gel and partly in liquid form in an on-chip enclosure molded using a 3d printer or made out of poly (dimethylsiloxane). The realized batteries provide a stable voltage (similar to 1.1 V) for many hours and exhibit capacities as high as 15 mu Ah, providing enough power to operate a pocket calculator. The realized batteries show promise for deployment as on-chip power sources for autonomous systems in lab-on-a-chip or biomedical applications

Effects of Self-Assembled Materials Prepared from V(2)O(5) for Lithium Ion Electroinsertion

Self-assembled materials consisting of V(2)O(5), polyallylamine (PAR) and silver nanoparticles (AgNPs) were obtained by the layer-by-layer (LbL) method, aiming at their application as electrodes for lithium-ion batteries and electrochromic devices. The method employed herein allowed for linear growth of visually homogeneous films composed of V(2)O(5), V(2)O(5)/PAH, and V(2)O(5)/PAH/AgNP with 15 bilayers. According to the Fourier transform infrared spectra, interaction between the oxygen atom of the vanadyl group and the amino group should be responsible for the growth of these films. This interaction also enabled establishment of an electrostatic shield between the lithium ions and the sites with higher negative charge, thereby raising the ionic mobility and consequently increasing the energy storage capacity and reducing the response time. According to the site-saturation model and the electrochemical and spectroelectrochemical results, the presence of PAH in the self-assembled host matrix decreased the number of V(2)O(5) electroactive sites. Thus, AgNPs were stabilized in PAR and inserted into the nanoarchitecture, so as to enhance the specific capacity. This should provide new conducting pathways and connect isolated V(2)O(5) particles in the host matrix. Therefore, new nanoarchitectures for specific interactions were formed spontaneously and chosen as examples in this work, aiming to demonstrate the potentiality of the adopted self-assembled method for enhancing the charge transport rate into the host matrices. The obtained materials displayed suitable properties for use as electrodes in lithium batteries and electrochromic devices.FAPESP[2009/14181-1]FAPESP[2009/15558-1]NanoBiotec-Brasil (CAPES)Instituto Nacional em Eletronica Organica (INEO)NanoBioMed-Brasil Network (CAPES

Política 2.0 : os deputados de Viseu nas redes sociaisnovas tendências de comunicação e marketing político em Portugal

Com a emergência das novas Tecnologias de Informação e Comunicação, os políticos debatem-se com novas formas de fazer chegar a sua mensagem aos cidadãos. A Internet trouxe para a Política um ambiente em rede onde os cidadãos se conseguem fazer ouvir e têm acesso a diversas formas de produção e receção de informação. Marcar a diferença e aproximar-se dos eleitores são objetivos ambicionados pelos políticos ao investirem na sua presença online. Em Portugal, o Marketing Político parece dar os primeiros passos no recurso à Internet para fazer campanha, com destaque para a utilização das Redes Sociais digitais. O presente Projeto de Investigação procura elaborar um estudo que convide à reflexão sobre a importância das Redes Sociais ao serviço da Política e perceber se o futuro da Comunicação e do Marketing Político em Portugal passa mesmo por explorar a imagem virtual dos políticos. Abordando as Redes Sociais como uma nova ferramenta de Marketing Político, recorrendo a revisão bibliográfica alargada, à aplicação e análise de entrevistas e à observação da presença, atividade desenvolvida e relações estabelecidas nas Redes Sociais, neste Projeto de Investigação procura-se compreender como estão os deputados do círculo eleitoral de Viseu a integrar as Redes Sociais como ferramenta de Comunicação e Marketing Político.With the rise of the new Information and Communication Technologies, politicians are struggling with new ways to convey their message to citizens. The Internet has brought into Politics a networked environment in which citizens have a voice and access to several forms of production and reception of information. By investing in their online presence, politicians aim at making a difference and becoming closer to voters. In Portugal, Political Marketing seems to be taking its first steps in the use of the Internet for campaigning, especially the use of digital Social Networks. This research project seeks to provide a study which invites to reflect on the importance of digital Social Networks in Politics and for politicians, and to question if the future of Communication and Political Marketing in Portugal will explore the virtual image of politicians. Addressing Social Networks as a new tool of Political Marketing, using extensive literature review, through the application and analysis of interviews, and the observation of politicians' presence, activity and relationships established on Social Networks, this research project seeks to understand how the members of the Viseu election circle are integrating Social Networks as a tool of Communication and Political Marketing

Enhancing the Electrochemical and Electronic Performance of CVD-Grown Graphene by Minimizing Trace Metal Impurities

The presence of unwanted impurities in graphene is known to have a significant impact on its physical and chemical properties. Similar to carbon nanotubes, any trace metals present in graphene will affect the electrocatalytic properties of the material. Here, we show by direct electroanalysis that traces of copper still remain in transferred CVD (chemical vapor deposition)-grown graphene (even after the usual copper etching process) and strongly influence its electrochemical properties. Subsequently, we use a real-time electrochemical etching procedure to remove more than 90% of the trace metal impurities, with a clear improvement in both the electrochemical and electronic-transport properties of monolayer graphene

Highly stable magnetite modified with chitosan, ferrocene and enzyme for application in magneto-switchable bioelectrocatalysis

Magnetic fields have been used in Bioelectrochemistry to carry enzymes or redox mediators immobilized on magnetite (Fe3O4) to the electrodes surface, providing a switchable control of faradaic current from biocatalysis. In this work, it is reported an advance in the magnetic control of bioelectrochemical reactions, by construction of a system containing simultaneously a magnetic particle (for controlled driving), an enzyme (for biocatalysis) and a redox mediator (for mediation of electron transfer). The advance was attained by synthesis of a new material (Fe3O4-Chi-Fc/GOx) that consists of Fe3O4 particles modified with insoluble ferrocene (Fc) and chitosan (Chi) cross-linked with glucose oxidase (GOx). When this material was used in electrochemical studies, an increase of 70% was observed in the catalytic current of glucose oxidation when 0.24 T was applied perpendicularly to electrode plane. This is the first time that a control of the bioelectrocatalytic process was achieved using enzyme, mediator and magnetite in a unique system switched by a magnetic field