Heteroatom dopant strategy triggered high-potential plateau to non-graphitized carbon with highly disordered microstructure for high-performance sodium ion storage

Non-graphitized carbon(NGC)has been extensively utilized as carbonaceous anode in sodium-ion batteries(SIBs).However,more optimization to achieve competitive capacity and stability is still challenging for SIBs.In the study,the dopant strategy is utilized to construct nitrogen/sulfur-doped non-graphitized carbon(N-NGC or S-NGC)shell decorated on three-dimensional graphene foam(GF)as a self-support electrode.The highly disordered microstructures of heteroatom doped carbons are produced by applying a low-temperature pyrolysis treatment to precursors containing nitrogen and sulfur.The DFT calculations of Na-ion adsorption energies at diverse heteroatom sites show marginal-S,pyrrolic N and pyridinic N with more intensive Na-ion adsorption ability than middle-S,C=O and pristine carbon.The N-NGC with dominant small graphitic regions delivers adsorption ability to Na-ion,while the S-NGC with significant single carbon lattice stripes demonstrates redox reaction with Na-ion.Evidently,in comparison with only adsorption-driven slope regions at high potential for N-NGC,the redox reaction-generated potentialplateau enables non-graphitized S-NGC superior discharge/charge capacity and cycle-stability in the slope region.This work could provide deep insight into the rational design of non-graphitized carbon with rich microstructure and composition.

Electrocatalytic conversion of waste polyamide-66 hydrolysates into high-added-value adiponitrile and hydrogen fuel

To reduce environmental pollution and plastic recycling costs,poly-amide-66(PA-66)as the most consumed engineering polymer needs to be recycled effectively.However,the existing recycling methods cannot convert waste PA-66 into valuable chemicals for upcycling under ambient conditions.Here,we report an integrated hydrolysis and electrocatalytic process to upcycle waste PA-66 into valuable adiponitrile(ADN),adipic acid,and H_(2) commodities,thereby closing the PA-66 loop.To enable electrooxidation of the PA-66 hydrosylate hexamethylenediamine(HMD),we fabricated anode catalysts with hierarchical Ni_(3)S_(2)@Fe_(2)O_(3) core-shell heterostructures comprising spindle-shaped Ni_(3)S_(2) cores and Fe_(2)O_(3) nanosheet shells.The unique core-shell architecture and synergy of the Ni_(3)S_(2) and Fe_(2)O_(3) catalysts enabled the selective dehydrogenation of C-N bonds from HMD to nitrile C≡N bonds,forming ADN with near-unity Faradaic efficiency at 1.40 V during the 100-h stability test even at 100 mA cm^(−2).X-ray photoelectron spectroscopy revealed that the Ni(Fe)oxy(hydroxide)species formed were in the active state during oxidation,accelerating the activation of the amino C-N bond for dehydrogenation directly into the C≡N bonds.

Three-dimensional reconstruction of a point immersed in water and application to a single rising bubble

The ability to reconstruct an object submerged in water is instrumental in scenarios such as the study of a rising bubble trajectory, and subsequently, its motion and force balance. In this paper, we propose a method that can reconstruct the three-dimensional position of a scene point immersed in water, while taking into account the refraction-induced distortion at the air-water interface between the point and camera. The scene point is captured by two orthogonally placed high-speed cameras, providing a pair of images through which the point's image coordinates are obtained. With pre-calibrated camera matrices, the world coordinates of the point’s position can be correctly calculated using a triangulation method, provided the scene point is in air. However, because of refraction, triangulating the image pairs of the point submerged in water results in erroneous world coordinates. Thus, we propose a method to correct the point's image coordinates to account for refraction induced distortion during reconstruction. The method was first verified by reconstructing the coordinates of square corners on a checkerboard, which produced results that deviated from the real value by 0.18%, as opposed to the 5.15% false enlargement prior to correction. Then, we applied the method to the reconstruction of the three-dimensional trajectories of single rising spherical bubbles, whose results were in favorable agreement with previous studies.