Dual-feedback healing mechanism redefining anti-oxidation coatings in fiber-reinforced composites

This study introduces a pioneering design concept termed the“dual-feedback healing mechanism”,which investigates the relationship between oxidation products and protective coatings.Specifically,it focuses on channeling oxidation products generated at exposed cracks in the substrate to interact with the antioxidant coatings,enabling a self-repair mechanism for cracks.BNf/SiBN was chosen as the ceramic matrix,while the Si-O-Al system served as the antioxidant coating.The dynamic process of obtaining Si-O-Al(SOAC)coating involving the pyrolysis of organic precursors and the dual-feedback healing mechanism were systematically investigated.These findings indicate that when the temperature surpasses 1150℃,the exposed BN fibers at the cracks are oxidized,transforming into B_(2)O_(3)(g).Subsequently,B_(2)O_(3)(g)reacts with SiO_(2),forming a SiBO mixture.The mixture effectively diminishes the viscosity of the coating,enabling it to flow and form a fresh protective layer that effectively blocks O_(2) infiltration.Consequently,after oxidation at 1500℃,the coated samples experience a mere 3%weight loss.This technology emphasizes the interconnectivity during material transformation,utilizing matrix oxidation products as a driving force for self-healing of the coating.This approach achieves intelligent-like,targeted closure of oxygen pathways,thereby pioneering a novel concept and direction for the advancement of antioxidant coatings.Consequently,this approach not only enhances our understanding of the fundamental nature of“self-healing”but also holds significant potential in the development of reparable antioxidant coatings.

Interfacial engineering of SnO_(2)/Bi_(2)O_(2)CO_(3)heterojunction on heteroatoms-doped carbon for high-performance CO_(2)electroreduction to formate

Electrochemical CO_(2)reduction is a viable,economical,and sustainable method to transform atmospheric CO_(2)into carbon-based fuels and effectively reduce climate change and the energy crisis.Constructing robust catalysts through interface engineering is significant for electrocatalytic CO_(2)reduction(ECR)but remains a grand challenge.Herein,SnO2/Bi_(2)O_(2)CO_(3)heterojunction on N,S-codoped-carbon(SnO_(2)/BOC@NSC)with efficient ECR performance was firstly constructed by a facile synthetic strategy.When the SnO_(2)/BOC@NSC was utilized in ECR,it exhibits a large formic acid(HCOOH)partial current density(JHCOOH)of 86.7 mA·cm^(−2)at−1.2 V versus reversible hydrogen electrode(RHE)and maximum Faradaic efficiency(FE)of HCOOH(90.75%at−1.2 V versus RHE),respectively.Notably,the FEHCOOH of SnO_(2)/BOC@NSC is higher than 90%in the flow cell and the JHCOOH of SnO_(2)/BOC@NSC can achieve 200 mA·cm^(−2)at−0.8 V versus RHE to meet the requirements of industrialization level.The comparative experimental analysis and in-situ X-ray absorption fine structure reveal that the excellent ECR performance can be ascribed to the synergistic effect of SnO_(2)/BOC heterojunction,which enhances the activation of CO_(2)molecules and improves electron transfer.This work provides an efficient SnO_(2)-based heterojunction catalyst for effective formate production and offers a novel approach for the construction of new types of metal oxide heterostructures for other catalytic applications.