Graphitic carbon nitride (g-C3N4) is a rising two-dimensional material possessing intrinsic semiconducting property with unique geometric configuration featuring superimposed heterocyclic sp(2) carbon and nitrogen network, nonplanar layer chain structure, and alternating buckling. The inherent porous structure of heptazine-based g-C3N4 features electron-rich sp(2) nitrogen, which can be exploited as a stable transition metal coordination site. Multiple metal-functionalized g-C3N4 systems have been reported for versatile applications, but local coordination as well as its electronic structure variation upon incoming metal species is not well understood. Here we present detailed bond coordination of divalent iron (Fe(2+)) through micropore sites of graphitic carbon nitride and provide both experimental and computational evidence supporting the aforementioned proposition. In addition, the utilization of electronic structure variation is demonstrated through comparative photocatalytic activities of pristine and Fe-g-C3N4.

Energy-efficient CO2 capture is a stringent demand for green and sustainable energy supply. Strong adsorption is desirable for high capacity and selective capture at ambient conditions but unfavorable for regeneration of adsorbents by a simple pressure control process. Here we present highly regenerative and selective CO2 capture by carbon nitride functionalized porous reduced graphene oxide aerogel surface. The resultant structure demonstrates large CO2 adsorption capacity at ambient conditions (0.43 mmol·g(-1)) and high CO2 selectivity against N2 yet retains regenerability to desorb 98% CO2 by simple pressure swing. First-principles thermodynamics calculations revealed that microporous edges of graphitic carbon nitride offer the optimal CO2 adsorption by induced dipole interaction and allows excellent CO2 selectivity as well as facile regenerability. This work identifies a customized route to reversible gas capture using metal-free, two-dimensional carbonaceous materials, which can be extended to other useful applications.

Cast Al-Si alloys have been widely used in automotive applications with regard to their low density and excellent thermal conductivity. Many components made of these alloys are subjected to cyclic loads which can lead to fatigue failure. Furthermore, for these materials the well know size effect in fatigue, whereby the fatigue strength is reduced when the size is increased, can be significant and need to be properly evaluated. This paper analyses the role of casting defects on the fatigue strength's size effect sensitivity. A uniaxial fatigue testing campaign (R=0.1) has been conducted using two cast aluminium alloys, fabricated by different casting processes (gravity die casting and lost foam casting), associated with the T7 heat treatment, and with different degrees of porosity. The fatigue response of different specimens (smooth and notched) with different stressed volumes has been investigated. The first part of this article is dedicated to the experimental characterization of the size effect in both alloys via the concept of the Highly Stressed Volume. The second part investigates the effect of the Highly Stressed Volume on the critical defect size via Kitagawa-Takahashi diagrams. The results show that the magnitude of the size effect and the experimental scatter are strongly linked to the characteristics of the defect population present in the alloy. It is revealed that the alloy B, with a high density of pore and a population of defects with relatively large size, shows non-significant size effect and less scatter in fatigue strength. In comparison, alloy A that exhibits a low density of pore and a population of defects of relatively small size manifests significant size effect and high scatter in fatigue strength.