Electrocatalysis plays a central role in clean energy conversion, enabling a number of sustainable processes for future technologies and the development of highly efficient and cost‐effective materials is one of the current major challenges. This results from the current global energy crisis, reflected in the depletion of fossil fuels and growth of the environmental pollution, which has stimulated the development of novel renewable energy storage and conversion technologies. Currently, several electrocatalysts have been proposed and among them are the polyoxometalates (POMs), the metal‐organic frameworks (MOFs) and their based composites.

We report the application of two poly [Ni(salen) was used to fabricate a solid state electrochromic device using lateral configuration with two figures of merit: a simple shape (typology 1) and a butterfly shape (typology 2); typology 1 showed the best performance with optical contrast ∆T = 88.7 % (at λ = 750 nm), colouration efficiency η = 130.4 cm 2 C -1 and charge loss of 37.0 % upon 3000 redox cycles.]

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Functional materials as electrocatalysts for the oxygen reduction reaction (ORR) are crucial for several renewable energy applications. Herein, we report the application of several nanocomposites, prepared by the incorporation of a vanadium‐substituted phosphomolybdate [PMo11VO40]4− (PMo11V) into some carbon‐based materials (carbon black (CBV), single‐walled carbon nanotubes (SWCNT) and graphene (GF)), as ORR electrocatalysts. All nanocomposites, denominated as PMo11V@CBV, PMo11V@SWCNT and PMo11V@GF, show electrocatalytic activity for the ORR in acidic medium (pH 2.5 H2SO4/Li2SO4 buffer solution), with a strong dependency between the electrocatalytic ORR performance and the carbon‐based material employed. Among the materials studied, the PMo11V@GF nanocomposite exhibits the most promising performance, having the less negative onset potential (Eonset=‐0.16 V vs. Ag/AgCl (0.18 V vs. RHE)), which is explained by the excellent electronic properties of GF. An ORR process based in a 2‐electron mechanism is assumed for all modified electrodes. The PMo11V‐ and the nanocomposite‐modified electrodes are also effective for the reduction of hydrogen peroxide, with PMo11V@GF displaying the most promising electrocatalytic performance. The successful preparation of the nanocomposites is confirmed by X‐ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy techniques. The electrochemical characterization of all modified electrodes is also reported.

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ORR electrocatalysts derived from sugar: activated carbons derived from sucrose showed electrocatalytic activity for the oxygen reduction reaction.

A new nanocomposite was obtained through the incorporation of N-doped few layer graphene (N-FLG) into films of the electroactive polymer poly[Ni(3-Mesalen)] (poly[1]). The nanocomposite, N-FLG@poly[1], prepared by in situ electropolymerization, showed similar electrochemical responses to pristine poly[1], but with more well-defined redox peaks and higher current intensities, in compliance with larger electroactive surface coverage. N-FLG incorporation did not affect the electronic structure of poly[1], but decreased in 12 % the molar extinction coefficient of the charge transfer band between metal and oxidized ligand, which is a promising advantage since this band is related to polymer degradation. The N-FLG@poly[1] showed multi-electrochromic behaviour (yellow in reduced state and green / russet in oxidised states) and revealed excellent improvement in electrochromic performance compared to original poly[1], specifically an increase of 71 % in electrochemical stability (loss of 2.7% in charge after 10 000 switching cycles). Furthermore, nanocomposite formation decreased the switching time for oxidation (reduction)  = 9 s (11 s) and improved the optical contrast (T = 35.9%; increase of 38%) and colouration efficiency ( = 108.9 cm 2 C-1 ; increase of 12 %), for a representative film of coverage  = 296 nmol cm-2. The excellent electrochromic performance improvements are attributed to the alternative conducting pathways and to morphological modifications induced by N-FLG. with enhanced EC properties have also been reported, combining polyaniline (PANI) and pyrrole-derivatives with graphene [4,26], sulfonated-graphene [27], graphene oxide [28] or reduced graphene oxide [6], as counterparts. Ma et al. [1] reported the preparation of an electrochromic polyschiff base functionalised with reduced graphene oxide. More recently, the chemical doping of graphene with heteroatoms (nitrogen, boron and sulphur) has emerged as an important approach to tailor the electrical, morphological and chemical properties of pristine graphene. Nitrogen is the most commonly used dopant, mainly due to its similar atomic radius to carbon, which prevents significant lattice mismatch [29,30]. The main differences between nitrogen-doped graphene (N-G) and pristine graphene are (i) the spin density and charge distribution on the carbon atoms (influenced by the neighbour nitrogen dopants) and (ii) the open band gap, making N-G an n-type semiconductor [31], which is very useful for nanoelectronic applications. In the

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