Pedro Gómez-Romero

Hybrid Organic–Inorganic Materials—In Search of Synergic Activity

This review surveys the work developed in the field of functional hybrid materials, especially those containing conducting organic polymers (COPs), in combination with a variety of inorganic species, from molecular to extended phases, including clusters and nano-sized inorganic particles. Depending on the dominating structural matrix, we distinguish and analyze organic–inorganic (OI) hybrids, nanocomposite materials, and inorganic–organic (IO) phases. These materials have been used in a wide variety of applications, including energy-storage applications, electrocatalysis, the harnessing of electrochromic and photoelectrochromic properties, application in display devices, photovoltaics, and novel energy-conversion systems, proton-pump electrodes, sensors, or chemiresistive detectors, which work as artificial “noses”.

Polymer Electrolyte Fuel Cells Based on Phosphoric Acid-Impregnated Poly(2,5-benzimidazole) Membranes

b Institut Quimic de Sarria `, Universitat Ramon Llull, E-08017 Barcelona, Spain Preparation and characterization of membranes of poly~2,5-benzimidazole !~ ABPBI !~ as thin as 20 mm! for polymer electrolyte membrane fuel cells are reported. These membranes were prepared by solution casting and then impregnated in phosphoric acid baths. Their characterization included thermogravimetric analyses, conductivity measurements, Fourier transform infrared spec- troscopy, X-ray diffraction, and scanning electron microscopy. These membranes have high thermal stability and good proton conductivity at temperatures up to 200°C (6.23 10 22

Hybrid organic-inorganic nanocomposite materials for application in solid state electrochemical supercapacitors

Integration into a conducting polymer matrix to form a hybrid material is an effective way to harness the electrochemical activity of nanosized oxide clusters. By anchoring them into polyaniline, the reversible redox chemistry of the otherwise soluble polyoxometalate clusters can be combined with that of the conducting polymer and be put to work in energy storage applications. We present here preliminary results that show how the resulting hybrid polymer displays the combined activity of its organic and inorganic components to store and release charge in a solid state electrochemical capacitor device.

The Organic-Inorganic Polyaniline/V2O5 System. Application as a High-Capacity Hybrid Cathode for Rechargeable Lithium Batteries

This work was partially supported by CICYT (Spain, MAT98-0807-C02-02). We also thank the Ministerio de Educacion y Ciencia (Spain, MEC-AECI) and CONACYT (Mexico) for a predoctoral fellowship to M.L.C.

Low-cost flexible supercapacitors with high-energy density based on nanostructured MnO2 and Fe2O3 thin films directly fabricated onto stainless steel.

The facile and economical electrochemical and successive ionic layer adsorption and reaction (SILAR) methods have been employed in order to prepare manganese oxide (MnO2) and iron oxide (Fe2O3) thin films, respectively with the fine optimized nanostructures on highly flexible stainless steel sheet. The symmetric and asymmetric flexible-solid-state supercapacitors (FSS-SCs) of nanostructured (nanosheets for MnO2 and nanoparticles for Fe2O3) electrodes with Na2SO4/Carboxymethyl cellulose (CMC) gel as a separator and electrolyte were assembled. MnO2 as positive and negative electrodes were used to fabricate symmetric SC, while the asymmetric SC was assembled by employing MnO2 as positive and Fe2O3 as negative electrode. Furthermore, the electrochemical features of symmetric and asymmetric SCs are systematically investigated. The results verify that the fabricated symmetric and asymmetric FSS-SCs present excellent reversibility (within the voltage window of 0–1 V and 0–2 V, respectively) and good cycling stability (83 and 91%, respectively for 3000 of CV cycles). Additionally, the asymmetric SC shows maximum specific capacitance of 92 Fg−1, about 2-fold of higher energy density (41.8 Wh kg−1) than symmetric SC and excellent mechanical flexibility. Furthermore, the “real-life” demonstration of fabricated SCs to the panel of SUK confirms that asymmetric SC has 2-fold higher energy density compare to symmetric SC.

Hybrid materials. Functional properties. From Maya Blue to 21st century materials

The field of hybrid organic-inorganic materials has reached a stage of ripeness that is beginning to make possible extraordinary new developments. On the one hand the field has witnessed a trend towards the design of functionality in hybrids materials, while broadening spectacularly the variety of hybrid combinations explored. On the other hand, improved understanding and control of the chemistry, processing and microstructure of these versatile nanocomposite systems announce a new landscape of opportunities in dealing with increasingly complex chemistries and materials.

Polyoxometalates: from inorganic chemistry to materials science.

Polyoxometalates have been traditionally the subject of study of molecular inorganic chemistry. Yet, these polynuclear molecules, reminiscent of oxide clusters, present a wide range of structures and with them ideal frameworks for the deployment of a plethora of useful magnetic, electroionic, catalytic, bioactive and photochemical properties. With this in mind, a new trend towards the application of these remarkable species in materials science is beginning to develop. In this review we analyze this trend and discuss two main lines of thought for the application of polyoxometalates as materials. On the one hand, there is their use as clusters with inherently useful properties on themselves, a line which has produced fundamental studies of their magnetic, electronic or photoelectrochemical properties and has shown these clusters as models for quantum-sized oxides. On the other hand, the encapsulation or integration of polyoxometalates into organic, polymeric or inorganic matrices or substrates opens a whole new field within the area of hybrid materials for harnessing the multifunctional properties of these versatile species in a wide variety of applications, ranging from catalysis to energy storage to biomedicine.

3D hierarchical assembly of ultrathin MnO2 nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li- doped ionic liquid

Building of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO2@silicon nanowires (MnO2@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl)imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO2@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2 V and exhibits a high areal capacitance of 13 mFcm−2. The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO2 nanoflakes are responsible for the remarkable performance of these MnO2@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors.

Hybrid energy storage: high voltage aqueous supercapacitors based on activated carbon–phosphotungstate hybrid materials

The use of hybrid electrodes prepared from phosphotungstic acid (H3PW12O40, PW12) and activated carbon (AC) allows the fabrication of highly durable aqueous supercapacitors operating at a superior voltage (1.6 V) thanks to the high overpotential of PW12 towards H2 generation. The combination of the double-layer capacitance plus the redox activity of the polyoxometalate clusters leads to an intrinsic increase in specific capacitance (from 185 F g−1 for AC to 254 F g−1 for AC–PW12) and a 60% increase in the operating voltage (compared to conventional AC supercapacitors with aqueous electrolytes, e.g. 1 M sulphuric acid). The hybrid energy storage mechanism and the increased operating voltage converge to yield improved specific energy and power. Moreover, the hybrid AC–PW12 electrode material showed an outstanding stability even after 30 000 cycles (0 to 1.6 V) with 98% retention of the initial capacitance, much superior to the stability of the parent supercapacitor based on plain AC under the same conditions.

Facile one-pot synthesis of self-assembled silver@polypyrrole core/shell nanosnakes.

We thank the CSIC and the European Social Fund for financing through the I3P program, project MAT2005-07683-C02-01, and financial support for O.A. from the Saudi Committee for the Relief of Palestinian People and the Palestinian Ministry of Higher Education.