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Sodium‐ion capacitors (SICs) have great potential in energy storage due to their low cost, the abundance of Na, and the potential to deliver high energy and power simultaneously. This article demonstrates a template‐assisted method to induce graphitic nanodomains and micro‐mesopores into nitrogen‐doped carbons. This study elucidates that these graphitic nanodomains are beneficial for Na+ storage. The obtained N‐doped carbon (As8Mg) electrode achieved a reversible capacity of 254 mA h g−1 at 0.1 A g−1. Moreover, the As8Mg‐based SIC device achieves high combinations of power/energy densities (53 W kg−1 at 224 Wh kg−1 and 10 410 W kg−1 at 51 Wh kg−1) with outstanding cycle stability (99.7% retention over 600 cycles at 0.2 A g−1). Our findings provide insights into optimizing carbon's microstructure to boost sodium storage in the pseudocapacitive mode. [ABSTRACT FROM AUTHOR]

Polymeric semiconductors are finding a wide range of applications. In particular, graphitic carbon nitride g‐C3N4 has been investigated extensively in the past decade. However, the family of carbon nitrides is not limited to C3N4 and new CXNY are now being explored due to their different bandgap energy, morphology, and overall physicochemical properties. Here, homogenous and semi‐transparent C1N1 thin films are fabricated using guanine as a nontoxic molecular precursor. They are synthesized in a simplified chemical vapor deposition process on top of fused silica and fluorine doped tin oxide coated glass substrates. The chemical and structural studies reveal that C/N ratio is close to target 1, triazine vibrations are visible in vibrational spectra and stacking of the film is observed from glancing incidence X‐ray diffraction data. The (photo)electrochemical properties are studied, the film is a p‐type semiconductor with a good photoresponse to visible light and a suitable catalyst for hydrogen evolution reaction. A simple and safe way of synthesizing C1N1 films on a range of substrates is presented here. [ABSTRACT FROM AUTHOR]

The influence of structural modifications on the catalytic activity of carbon materials is poorly understood. A collection of carbonaceous materials with different pore networks and high nitrogen content was characterized and used to catalyze four reactions to deduce structure–activity relationships. The CO2 cycloaddition and Knoevenagel reaction depend on Lewis basic sites (electron‐rich nitrogen species). The absence of large conjugated carbon domains resulting from the introduction of large amounts of nitrogen in the carbon network is responsible for poor redox activity, as observed through the catalytic reduction of nitrobenzene with hydrazine and the catalytic oxidation of 3,3′,5,5′‐tetramethylbenzidine using hydroperoxide. The material with the highest activity towards Lewis acid catalysis (in the hydrolysis of (dimethoxymethyl)benzene to benzaldehyde) is the most effective for small molecule activation and presents the highest concentration of electron‐poor nitrogen species. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate the tuning of the oxygen reduction reaction (ORR) using iron/iron oxide nanoparticle grafted laser-patterned nitrogen-doped carbon (LP-NC) electrodes. Depending on the preparation route, i.e. addition of a molecular Fe(NO3)2 precursor before (route 1) or after pre-carbonization (route 2) of the citric acid/urea precursors, either the 4e− or the 2e− pathway in the ORR is facilitated leading to either H2O or H2O2 as a reaction product, respectively. The kinetic reaction conditions afford mixed valence metal oxide nanoparticles embedded in LP-NC in the form of either Fe2O3/Fe or Fe2O3/FeO/Fe, respectively, facilitated by an in situ carbothermal reduction during the laser-induced carbonization. In HR(S)TEM analysis we found evidence for the occurrence of Fe2O3 in the η- or α-phase, depending on the preparation route. Reciprocally, the graphitization is also affected by the preparation route leading to either homogeneous graphitization or a locally graphitized shell structures around the nanoparticles. In the 4e− mediated ORR facilitated by η-Fe2O3/Fe@LP-NC onset potentials as low as 0.70 V (vs. RHE) with a H2O2 production efficiency of 4% and 10% in alkaline and neutral electrolyte, respectively, were determined. On the other hand, α-Fe2O3/FeO/Fe@LP-NC presents an onset potential for the 2e− mediated ORR as low as 0.77 V with a H2O2 production efficiency of nearly 80%. The changes in selectivity and physicochemical properties of the electrocatalysts by applying simple modifications in the synthetic route point to laser-patterning as a very promising route to scale up designer electrodes for electrochemical conversion. [ABSTRACT FROM AUTHOR]

The preparation of stable and efficient electrocatalysts comprising abundant and non-critical row-materials is of paramount importance for their industrial implementation. Herein, we present a simple synthetic route to prepare Mn(II) sub-nanometric active sites over a highly N-doped noble carbonaceous support. This support not only promotes a strong stabilization of the Mn(II) sites, improving its stability against oxidation, but also provides a convenient coordination environment in the Mn(II) sites able to produce CO, HCOOH and CH3COOH from electrochemical CO2 reduction. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) that for instance takes place at the cathode of fuel cells is one of the most examined model reactions of energy conversion. The ORR presents sluggish reaction kinetics, thus limiting the overall efficiency of these cells. Pt-based catalysts are still the widest choice though they exhibit important drawbacks such as long-term instability and intolerance to methanol crossover. In this context, engineering transition metals in the form of nano- and subnano-sites on carbonaceous supports has the potential of becoming an alternative to scarce noble metal-based catalysts. Herein, we describe a simple synthetic route towards CuII/CuI decorated N-doped carbonaceous ORR electrocatalysts. CuII/CuI nanosites are obtained by calcination in air of an ionic liquid derived noble carbonaceous support impregnated with copper(II) acetate. The strong interaction between the copper and the noble support foster the co-formation of CuII/CuI nanosites. Larger amounts of copper(II) acetate translate into larger amounts of CuI and lower Tafel slopes. The material with 4 wt% of copper catalyzes the selective reduction of oxygen through a 4-electron transfer pathway and exhibits a lower Tafel slope than commercial platinum, a minimal overpotential, and a higher limiting current density. Moreover, all materials show promising durability and high methanol stability, which makes them promising to replace noble metals for the ORR. [ABSTRACT FROM AUTHOR]

C2N is a unique member of the CnNm family (carbon nitrides), i.e., having a covalent structure that is ideally composed of carbon and nitrogen with only 33 mol% of nitrogen. C2N, with a stable composition, can easily be prepared using a number of precursors. Moreover, it is currently gaining extensive interest owing to its high polarity and good thermal and chemical stability, complementing carbon as well as classical carbon nitride (C3N4) in various applications, such as catalysis, environmental science, energy storage, and biotechnology. In this review, a comprehensive overview on C2N is provided; starting with its preparation methods, followed by a fundamental understanding of structure–property relationships, and finally introducing its application in gas sorption and separation technologies, as supercapacitor and battery electrodes, and in catalytic and biological processes. The review with an outlook on current research questions and future possibilities and extensions based on these material concepts is ended. [ABSTRACT FROM AUTHOR]