ABSTRACT
It is essential for the widespread application of proton exchange membrane fuel cells (PEMFCs) to investigate low-cost, extremely active, and long-lasting oxygen reduction catalysts. Initial performance of PGM-free metal-nitrogen-carbon (M-N-C) catalysts for oxygen reduction reaction (ORR) has advanced significantly, particularly for Fe-N-C-based catalysts. However, the insufficient stability of M-N-C catalysts still impedes their use in practical fuel cells. In this review, we focus on the understanding of the structure-stability relationship of M-N-C ORR catalysts and summarize valuable guidance for the rational design of durable M-N-C catalysts. In the first section of this review, we discuss the inherent degrading mechanisms of M-N-C catalysts, such as carbon corrosion, demetallation, H2 O2 attack, etc. As we gain a thorough comprehension of these deterioration mechanisms, we shift our attention to the investigation of strategies that can mitigate catalyst deterioration and increase its stability. These strategies include enhancing the anti-oxidation of carbon, fortifying M-N bonds, and maximizing the effectiveness of free radical scavengers. This review offers a prospective view on the enhancement of the stability of non-noble metal catalysts.
ABSTRACT
The high cost and poor reliability of cathodic electrocatalysts for the oxygen reduction reaction (ORR), which requires significant amounts of expensive and scarce platinum, obstructs the broad applications of proton exchange membrane fuel cells (PEMFCs). The principles of ORR and the reasons for the poor stability of Pt-based catalysts are reviewed. Moreover, this paper discusses and categorizes the strategies for enhancing the stability of Pt-based catalysts in fuel cells. More importantly, it highlights the recent progress of Pt-based stability toward ORR, including surface-doping, intermetallic structures, 1D/2D structures, rational design of support, etc. Finally, for atomic-level in-depth information on ORR catalysts in fuel cells, potential perspectives are suggested, such as large-scale preparation, advanced interpretation techniques, and advanced simulation. This review aims to provide valuable insights into the fundamental science and technical engineering for practical Pt-based ORR electrocatalysts in fuel cells.
ABSTRACT
Background: In recent years, parent-mediated intervention for children with autism spectrum disorder (ASD) has increased. Therefore, implementing effective parent training programs for parents of children with autism is of paramount importance, particularly in low- and middle-income countries. However, little is known about the status of and gaps in parents' knowledge on ASD, which may hinder the development of valid parental training programs. Herein, we aimed at exploring the status of Chinese parents' knowledge, attitude and behavior toward ASD, and potential factors affecting the acquisition of correct knowledge. Methods: This study used a self-designed parental knowledge questionnaire of autism (PKQA) comprising 20 questions alongside another questionnaire comprising additional 17 questions covering the aspects of family demographics, attitudes, and behaviors of parents. In total, we included 394 parents who visited the outpatient department of the Child's Development and Behavior Center of the Third Affiliated Hospital of Sun Yat-Sen University between December 2018 and May 2019, with their children meeting the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnostic criteria for ASD. Results: The median knowledge score in the PKQA was 15 [interquartile range (IQR), 13-17]. Advanced paternal age and longer time interval from diagnosis to enrolling into the parent training program were associated with a lower total knowledge score (all P<0.001). Higher maternal education attainment, higher family income, child being currently under intervention, and family members sharing a common perception of the diagnosis were associated with a higher total knowledge score (all P<0.01). Reading autism-related books (P<0.001) or attending professional lectures (P=0.019) were also associated with a higher total knowledge score. Conclusions: Taken together, this study revealed that family demographics and parents' attitudes and behaviors toward ASD may significantly influence their knowledge about autism, suggesting the need for promoting more targeted parental skills training programs.
