Flexible and low-cost binderless capacitors based on p- and n-containing fibrous activated carbons from denim cloth wastes

Activated carbon cloths have been prepared from denim cloth wastes (DCWs) through chemical activation with H3PO4. The effect of the H3PO4/DCWs impregnation ratio and the carbonization temperature on the porous texture, the chemical composition, the fibers morphology, and the electrochemical performance has been studied. Low H3PO4/DCWs impregnation ratios lead to flexible and microporous activated carbons cloths, whereas more fragile and rigid activated carbon cloths with higher external surface area are produced upon increasing the amount of H3PO4. The increase in the carbonization temperature allows for obtaining a more ordered and conductive carbon structure. The activated carbon prepared at 900 ºC with a H3PO4/DCWs impregnation ratio of 0.5 (w/w) exhibits the best performance as electric double layer capacitor. This electrode shows a specific surface area of 2016 m2 g-1 and the highest registered gravimetric capacitance (227 F g-1). Moreover, its flexibility minimizes the ohmic resistance of the electrode, thus increasing the feasibility of working at higher current densities than the other synthesized electrodes.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech; MINECO CTQ2015-68654-

Alcohol decomposition on basic/acid lignin-derived submicron diameter carbon fibers

The use of lignin, the second most abundant polymer in nature, along with a simple and versatile technique, electrospinning, represents an advantageous and promising approach for the preparation of carbon fibers. In previous studies, we have demonstrated that the incorporation of H3PO4 to the initial lignin solution allows for shortening the carbon fibers preparation process and that the resulting carbon fibers present P-surface groups that are of great interest for heterogeneous catalysis. Different carbon fibers catalysts have been prepared by electropinning of Alcell lignin in the absence or presence of H3PO4 as chemical activating agent. Carbonization at different temperatures between 500 and 1600 ºC allows for preparing carbon fibers with a high variety of porosity and chemical surface properties. Diverse oxygen surface groups are presented on the carbon catalysts surface. The isopropanol decomposition has been used as a catalytic test to study the acid or basic character of the prepared carbon fibers. Carbon fibers without phosphorus surface groups generate acetone as the main product of the isopropanol decomposition reaction, from 400 to 600 ºC, suggesting the basic character of these catalysts. On the contrary, phosphorus-containing carbon fibers show high acid character, producing selectivity to propylene of 100 % at temperatures between 250 and 350 ºC. The most acid carbon fiber catalyst produced a high selectivity to ethylene and dimethyl ether for the decomposition of ethanol and methanol, respectively. The conversion enhancement that the presence of oxygen in the gas phase produced for all these reactions was also studied.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO (CTQ2015-68654-R). MINECO (PTA2015-11464-I)

High temperature treatments of porous activated carbon

The use of biomass waste for the preparation of activated carbon is of great industrial interest for reducing costs and increasing the sustainability, especially in the field of energy storage. A high temperature treatment is required to obtain a more ordered carbon material, thus increasing its conductivity. However, this high temperature treatment entails as a disadvantage a significant reduction in porosity. Therefore, a method to prepare activated carbons with a high porosity development as well as high conductivity could be of great interest for many applications. The aim of this work is to analyze the possible influence of phosphorus compounds on the physical-chemical properties of different carbon materials thermally treated at relatively high temperatures (1600 ºC). With this goal, it has been prepared activated carbons from different precursors (olive stone, lignin and hemp) and different conformations (powder, fibers and monoliths) by physical and chemical activation, with CO2 and H3PO4, respectively. Once the different activated carbon materials were prepared, they were thermally treated at 1600 ºC under inert atmosphere. The different samples were characterized by N2 and CO2 adsorption at 77 and 273 K, respectively, XPS, XRD and Raman techniques. The oxidation resistance was also evaluated in a thermogravimetric balance. High temperature treatments of activated carbon without the presence of P surface groups produced an important contraction of the porosity (from 900 to 150 m2 g-1). However, temperature treatments of phosphorus-activated carbon allowed for preparing carbon materials with a relatively high structural order and a well-developed porosity (c.a. 1100 m2 g-1), with a significant contribution of mesoporosity. These results suggest that these P-surface groups are responsible for the low contraction observed for the porous structure, avoiding, in a large extent, its collapse.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO (CTQ2015-68654-R). MINECO (PTA2015-11464-I)

Modification of the morphology, porosity and surface chemistry of lignin-based electrospun carbon materials

Lignin is a biopolymer that can be found as the main component of plants. It is obtained as a coproduct in the papermaking and biofuel industries. Owing to its high carbon and aromatic content, high availability and reduced cost, it is an excellent precursor for the preparation of highly valued carbon materials. Electrospinning is a suitable top-down technique for the preparation of polymeric fibers using high voltage electrical fields and polymer solutions of proper viscosity and conductivity. Organosolv lignins, which are extracted from lignocellulosic biomass using organic solvents, are soluble in ethanol, obtaining a solution that matches the requirement of the electrospinning process. In this way, it is possible to produce lignin-based porous carbon fibers using a coaxial electrospinning device [1]. This contribution summarizes our findings about the preparation of carbon materials with different morphologies and composition by processing lignin using electrohydrodynamic forces. Lignin spheres, beaded fibers, straight fibers, beaded tubes and straight tubes are obtained by using coaxial and triaxial spinnerets that allows the electrospinning of two or three different solutions at once [1], Fig. 1. Thermal stabilization in air is needed in order to avoid melting of lignin fibers during carbonization. Stabilization times of 48-96 hours are usually required in this step, decreasing the sustainability of the production process. Phosphoric acid can be added in small amounts in the lignin solution, shortening the time for achieve a successful thermostabilization of the fiber [2]. The carbonized materials show narrow microporosity and large surface area values (SBET from 600 to 1000 m2g-1) and additional pore size and volume can be developed by controlled gasification.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This work was supported by the Spanish Ministry of Economy and Competitiveness and FEDER (CTQ-2015-68654-R)

Activated carbons as catalytic support for Cu nanoparticles

There are a wide range of catalytic applications for Cu-based nanoparticles materials, since Cu is an abundant and inexpensive metal and Cu nanoparticles possess unusual electrical, thermal and optical properties. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. A previous work have explored the possibilities of SBA-15 (1,2) as support for Cu nanoparticles. In the present contribution, those results will be compared with the use of a carbon material as support, since activated carbon present many advantages with respect SBA, as the high surface area.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Novel lignin-based fibrous carbon materials

Lignin is (and will be) an important co-product in many lignocellulosic biomass-derived industries, such as pulp and paper mills (and the future biorefineries, when the concept of bio-economy be developed). The development of high-value products from lignin could mean a significant opportunity to reduce the associated costs and the environmental impacts of these industries [1]. In this sense, a new method to produce novel sub-micrometer carbon fibers and interconnected fibrous carbon webs materials (FCMs), showing unique advanced properties for different applications, by electrospinning [2] of phosphorous-containing lignin solutions is studied in this work. The different FCMs were prepared by electrospinning of Alcell lignin solutions with and without P–containing compounds, followed by stabilization and carbonization at different temperatures. For comparison purposes, equivalent lignin-based powdery carbon materials (PCMs) were also prepared from lignin powder without the electrospinning step. The different samples were characterized by N2 and CO2 adsorption, SEM, TEM, XRD, Raman, XPS, TPD and TG analysis. In the absence of P-containing groups, electrospun carbon fibers are continuous and linear (Fig 1.a), and show a specific surface area of 700 m2/g, much higher than that of carbon prepared in powdery shape (70 m2/g). The presence of P precursors in the lignin solution re-markably affects the electrospinning, sta-bilization and carbo-nization processes. By a suitable control of the stabilization heating rate, continuous and curly carbon fibers (Fig 1.b) or interconnected carbon fibrous webs (Fig 1.c) can be produced. In addition, the presence of 30wt% of P-containing compound in the lignin solution increases the specific surface area up to 1500 m2/g and enhances the oxidation resistance of the FCMs at high temperatures, what have been found very interesting for different applications, such as catalysis, adsorption and energy storage and conversion. These properties cannot be obtained in lignin-based carbon powders, even by using an 80wt% of P-containing compound for their chemical activation (1100 m2/g).Universidad de Málaga. Campus de Excelencia Andalucía Tech

Efecto del H3PO4 en la preparación de fibras de carbono a partir de lignina. Mejoras en el proceso de estabilización y propiedades finales

El presente trabajo propone un nuevo método de preparación de fibras de carbono mediante electrohilado de mezclas de lignina/H3PO4, en el que se obtienen resultados que aceleran el proceso de preparación de estos materiales así como sus propiedades físico-químicas en una sola etapa de preparación. Será objeto de estudio la temperatura, tiempo y velocidad de calentamiento en la etapa de estabilización así como la atmósfera (inerte u oxidante) de estabilización y carbonización.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

One-pot synthesis of lignin-based electrospun oxygen reduction reaction electrocatalysts

Owing to their adequate combination of high surface area, electrical conductivity and electrochemical resistance, carbon fibers has been used for a long time as a catalyst supports and gas diffusion layers in the electrodes of fuel cells. However, the use of high amounts of noble metals in the cathode is hampering the commercial utilization of fuel cells. We have recently demonstrated that the electrospinning of lignin, a widely available and non-expensive biopolymer, allows the production of porous carbon cloths, which have been already utilized as electrodes for methanol oxidation and supercapacitors. In this work, we propose the electrospinning of lignin and noble/non-noble metal precursors for one-pot production of ORR catalysts. Fe, Co, Pd and Pt salts have been incorporated onto lignin-ethanol solutions and have been electrospun in microsized, metal-decorated lignin fibers. The stabilization and carbonization of these fibers have produced carbon electrodes with supported metallic nanoparticles up to 10 % wt. loading, avoiding the use of further impregnation steps. In addition, the incorporation of metal precursors in the lignin solution enhances the development of mesoporosity in the resulting carbon fibers, a desirable feature for increasing mass transfer rate when used as electrocatalyst, without compromising their electrical conductivity. The electrochemical characterization has confirmed that these carbon cloths are promising ORR catalysts that could be useful for the reducing the amount of noble metals in the electrodes or for allowing the use of non-noble metals as catalysts.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO/FEDER CTQ2015-68654-R MINECO/FEDER CTQ2015-66080-R MINECO PTA2015-11464-

Advancing gender equ(al)ity, lifting men’s health: dealing with the spirit of our time

In this paper, we jointly address two connected issues that should be addressed together more purposefully within both public health policies and programmes: the health and well-being of men and boys, and the focus on equity versus equality from a gender perspective. Awareness of these issues has boosted the debate on the impacts of gender inequality on health and men’s role within it. Although this essay is not intended as an in-depth review on the subject, we provide a brief approach to some critical factors interwoven in the process of achieving greater gender equality. We identify some of the challenges that may arise for both policy and new research that seek to assume a relational gender approach that also pays greater attention to men’s health

The study of men’s health from a gender-based perspective: where we come from, where we are going

Llevar a cabo un análisis más integral y profundo de las diferencias y desigualdades en salud requiere de una aproximación más amplia al estudio de las masculinidades y la salud de los hombres en el momento actual. Estamos ante un tema cuyo interés ha ido a la par de la creciente preocupación por los riesgos y vulnerabilidades específicas de los hombres, pero también de la necesidad de involucrarlos en programas con capacidad de promover cambios positivos en el orden de género hacia la equidad en salud. Este artículo resitúa este campo dentro de la salud pública, proporcionando una visión amplificada sobre la salud de los hombres dentro del debate de los determinantes sociales de la salud y el análisis de las desigualdades. Sobre la base de un enfoque relacional de género, se formulan una serie de recomendaciones orientadas a las políticas y la investigación, que consideramos pueden contribuir a avanzar en el estudio y el desarrollo de programas desde una perspectiva de género en salud.Comprehensive and in-depth analyses of differences and inequalities in health require a broad-based approach to the study of masculinities and men’s health. Interest in this issue has grown in parallel to increased concern over specific risks and vulnerabilities faced by men, but also due to the need to involve them in programs capable of promoting progress towards gender-based health equity. This article attempts to reframe these issues from the perspective of public health, providing a wider viewpoint on men’s health situated within debates on the social determinants of health and the analysis of health inequalities. Based on a relational gender approach, we formulate some recommendations regarding policy and research agendas, which we argue can contribute to advancing the study and development of programs from a gender-based perspective in health