RESUMO
Most nonoxide catalysts based on transition metal elements will inevitably change their primitive phases under anodic oxidation conditions in alkaline media. Establishing a relationship between the bulk phase and surface evolution is imperative to reveal the intrinsic catalytic active sites. In this work, it is demonstrated that the introduction of Fe facilitates the phase transition of orthorhombic CoSe2 into its cubic counterpart and then accelerates the Co-Fe hydroxide layer generation on the surface during electrocatalytic oxygen evolution reaction (OER). As a result, the Fe-doped cubic CoSe2 catalyst exhibits a significantly enhanced activity with a considerable overpotential decrease of 79.9 and 66.9 mV to deliver 10 mA·cm-2 accompanied by a Tafel slope of 48.0 mV·dec-1 toward OER when compared to orthorhombic CoSe2 and Fe-doped orthorhombic CoSe2, respectively. Density functional theory (DFT) calculations reveal that the introduction of Fe on the surface hydroxide layers will tune electron density around Co atoms and raise the d-band center. These findings will provide deep insights into the surface reconstitution of the OER electrocatalysts based on transition metal elements.
RESUMO
Under the threat of the novel coronavirus, people are compelled to contemplate some ultimate existential questions, such as life and death. This study collected texts related to the death psychology from Sina Weibo, and after data cleaning, a total of 3868 Weibo texts were included. Study 1 employed grounded theory from qualitative research to explore the core categories and evolutionary mechanisms of people's psychology when facing death threats in the context of the pandemic. Study 2 utilized big data mining techniques such as topic mining and semantic network analysis to validate the effectiveness of the death psychology theory developed in qualitative research. The findings demonstrate that within the "Emotion-Cognition-Behavior-Value" framework, the implications of death threats manifest in four aspects: death anxiety, death cognition, coping efficacy, and sense of meaning. As time progresses, the study of death psychology can be segmented into four distinct phases: the tranquil phase prior to lifting pandemic restrictions, the threat phase at lifting pandemic restrictions onset, the coping phase mid-lifting pandemic restrictions, and the reformative phase post-lifting pandemic restrictions. The calculated outcomes of topic mining and semantic network analysis corroborate the coding results and theories derived from the grounded theory. This reaffirms that data mining technology can be a potent tool for validating grounded theory.
Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , Pandemias , SARS-CoV-2 , Cognição , ChinaRESUMO
The objective of this study is to delve into the underlying mechanisms between mindfulness and burnout among preschool teachers. Employing a cross-sectional research design, this study surveyed 1,980 Chinese preschool teachers using the Mindful Attention Awareness Scale (MAAS), Preschool Teacher Dispositional Equanimity Questionnaire (PTDEQ), Empathy Scale (ME), and Maslach Burnout Inventory for Educators (MBI-ES). The results revealed a significant negative correlation between preschool teachers' mindfulness and burnout. A mediation analysis demonstrated that dispositional equanimity served as a mediator between mindfulness and preschool teacher burnout. Furthermore, a moderation analysis indicated that empathy moderated the influence of dispositional equanimity on preschool teacher burnout. These findings suggest that mindfulness can enable preschool teachers to better cope with workplace challenges with a more peaceful mindset.
RESUMO
Preventing the deactivation of noble metal-based catalysts due to self-oxidation and poisonous adsorption is a significant challenge in organic electro-oxidation. In this study, we employ a pulsed potential electrolysis strategy for the selective electrocatalytic oxidation of glycerol to glyceric acid over a Pt-based catalyst. In situ Fourier-transform infrared spectroscopy, quasi-in situ X-ray photoelectron spectroscopy, and finite element simulations reveal that the pulsed potential could tailor the catalyst's oxidation and surface micro-environment. This prevents the overaccumulation of poisoning intermediate species and frees up active sites for the re-adsorption of OH adsorbate and glycerol. The pulsed potential electrolysis strategy results in a higher glyceric acid selectivity (81.8%) than constant-potential electrocatalysis with 0.7 VRHE (37.8%). This work offers an efficient strategy to mitigate the deactivation of noble metal-based electrocatalysts.