We study the oxygen reduction reaction (ORR) mechanism on the neighboring active sites of a B-doped pyrolyzed Fe−N−C catalyst using a combination of density functional theorybased calculations and microkinetic simulations. The structure of the neighboring FeN 4 and B-doped active sites facilitates the O 2 side-on adsorption for a facile dissociation process. This situation gives the B-doped catalyst system a flexibility to access both associative and dissociative reduction mechanisms. Such a mechanism does not exist in the undoped catalyst system because its dissociative mechanism is greatly hindered by the high activation energy for the O 2 dissociation reaction. The lowest calculated ORR overpotentials for the B-doped catalyst system through the associative and dissociative reduction mechanisms are 0.74 and 0.65 V, respectively. The ease of access to the dissociative reduction mechanism improves the ORR overpotential of the catalyst by ∼0.1 V with respect to the associative reduction mechanism. These results demonstrate the origin of superior performance of the B-doped pyrolyzed Fe−N−C catalyst system, which has been observed from experiments.

The interaction between neighbouring FeN4 and Psubs sites of a P-doped pyrolyzed Fe/N/C catalyst promotes four-electron reduction through associative and dissociative mechanisms.

Strong O2–ZnO(101̄0) interactions can only occur when the ZnO(101̄0) surface has either an O vacancy or a Zn–O dimer vacancy.

A new equation is proposed to explain the curvature of spent sparklers. We found the state of a segment of the sparkler to depend strongly on the state of its spent segments. The equation is nearly able to produce the sparkler shape for a range of lengths and for all elevation angles. The method proposed here is likely to explain any phenomena in nature related to an evolving length scale associated with some material that becomes progressively stiff or dry, such as the growth of resin exuded from trees. The equation can produce a very rich spectrum of shapes by varying material parameters (density, temperature-dependent strength), heating temperature, elevation angle, and gravitational acceleration. This might provide new insights into explaining many shapes in nature or man-made structures.

In this paper we study several aspects of extremal spherical symmetric black hole solutions of four dimensional N = 1 supergravity coupled to vector and chiral multiplets with the scalar potential turned on. In the asymptotic region the complex scalars are fixed and regular which can be viewed as the critical points of the black hole and the scalar potentials with vanishing scalar charges. It follows that the asymptotic geometries are of a constant and non-zero scalar curvature which are generally not Einstein. These spaces could also correspond to the near horizon geometries which are the product spaces of a two anti-de Sitter surface and the two sphere if the value of the scalars in both regions coincides. In addition, we prove the local existence of non-trivial radius dependent complex scalar fields which interpolate between the horizon and the asymptotic region. We finally give some simple l C n -models with both linear superpotential and gauge couplings.