Controlled Synthesis of Visible Light Active CuxS Photocatalyst: The Effect of Heat Treatment on Their Adsorption Capacity and Photoactivity

The effects of different precursor salts, stabilizing agents, and heat treatment parameters are already known to have an influence on the synthesis of nano-sized semiconductors in heterogenous photocatalysis. In the present work, CuxS materials were prepared by using different precursors (copper (II) chloride dihydrate or copper (II) acetate monohydrate) and shape tailoring/stabilizing agents, such as ethylenediaminetetraacetic acid/polyvinylpyrrolidone, and thiourea as the sulfur source. The polyvinylpyrrolidone (PVP) kinetically controlled the growth rate of the nanoplates, while ethylenediaminetetraacetic acid (EDTA) adjusted the nucleation process through the complexation of copper. A one-step hydrothermal method was used for the synthesis, and the materials were characterized by means of morphological and structural complementary investigation methods. Furthermore, the adsorption capacity and photocatalytic activity were also measured for these materials. It was found that the vacancy sites formed by changing the precursor salt, as confirmed by Raman measurements, affect the photocatalytic activity. The rise of the specific surface area was achieved by heat treatment, and concomitantly, the adsorption capacity of the treated samples was found to increase likewise

Különböző alakú nemesfémekkel módosított TiO2 fotokatalizátorok hatékonysága fotokatalitikus hidrogénfejlesztésben

TiO2 is one of the most frequently used semiconductor photocatalysts, because of its several beneficial properties: physical and chemical stability, nontoxicity, safety, low cost, and resistance to photocorrosion. In the present work we have successfully synthesized differently shaped Pd and Pt nanoparticles deposited onto the surface of commercial photocatalysts: Aldrich anatase, Aldrich rutile, or Evonik Aeroxide P25. The nanocomposites were investigated using DRS, XRD and TEM to uncover morphological, optical, and structural peculiarities of the nanoparticles and the composite photocatalysts. Finally, we tested their photocatalytic activity in photocatalytic hydrogen production processes and we have correlated the as obtained results with the morphology of Pd and Pt nanoparticles

Hőmérséklet hatása a réz-alapú fotokatalizátorok előállításában és hőkezelésében

Nanotechnology is a highly investigated research area, which includes photocatalysis applicable for water purification. This research area offers possible solutions to remove dangerous pollutants, such as pharmaceutical residues, or to create self-cleaning systems as well. The current issue in this scientific field is the efficient utilization of the visible light spectrum of the sunlight. Our main goal was to obtain copper-based photocatalysts, such as CuxO and CuxS (applying hydrothermal crystallization). Calcination was further used at different temperatures (400 - 600 °C) to increase the crystallinity and to induce changes in the morphology and structure of the materials. The samples were examined by X-ray diffraction for detection of crystal structure and Scanning electron microscopy for determination of the morphological properties. These materials can be used as photocatalysts in visible light

The Effect of the Reducing Sugars in the Synthesis of Visible-Light-Active Copper(I) Oxide Photocatalyst

In the present work, shape tailored Cu2O microparticles were synthesized by changing the nature of the reducing agent and studied subsequently. d-(+)-glucose, d-(+)-fructose, d-(+)xylose, d-(+)-galactose, and d-(+)-arabinose were chosen as reducing agents due to their different reducing abilities. The morpho-structural characteristics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS), while their photocatalytic activity was evaluated by methyl orange degradation under visible light (120 min). The results show that the number of carbon atoms in the sugars affect the morphology and particle size (from 250 nm to 1.2 µm), and differences in their degree of crystallinity and photocatalytic activity were also found. The highest activity was observed when glucose was used as the reducing agent

Humor and group atmosphere Development of a short scale for evaluating affiliative and aggressive humor in groups

Purpose - Given the importance of humor in interpersonal communication in groups and the influence of the positive group atmosphere on group effectiveness, this paper aims to provide initial empirical evidence supporting the validity of a short measure for affiliative and aggressive humor. Design/methodology/approach - Starting from existing individual-level measures of humor, this paper develops a short measure of affiliative and aggressive humor in groups. The reliability and validity of this scale in a combined Dutch and Romanian sample are tested. Findings - The results support the reliability of the scale, its factorial structure and its predictive validity for positive group atmosphere. Moreover, this papers shows that the measure used in this study captures the affiliative and aggressive humor as group-level phenomena and it is shown that these two forms of humor are antecedents of collective emotional intelligence and group atmosphere. Research limitations/implications - This study provides a starting point for further research on the role of affiliative and aggressive humor in groups. Originality/value - This paper develops a bi-dimensional measure capturing affiliative and aggressive humor in groups and opens new venues for research that extend the knowledge and understanding of the use of humor in interpersonal communication in groups

Minority dissent, social acceptance in collaborative learning groups

The main aim of this paper is to test the extent to which social acceptance moderates the impact of minority dissent on group cognitive complexity (GCC). We hypothesize that divergent views expressed by a minority increase GCC especially when the group climate is open to divergent contributions (e.g., a socially accepting group climate). We also hypothesize that group size has a non-linear association with GCC in such a way that GCC increases as group size increases from low to average and then GCC decreases as group size further increases from average to high. We test these hypotheses in a sample of 537 students (258 women, with an average age of 23.37) organized in 92 groups that have worked together in the same group throughout the semester, and show that: (1) group size has a decreasing positive association with GCC, (2) both minority dissent and social acceptance are beneficial for GCC and (3) groups with the highest GCC are those that experience minority dissent and develop a socially accepting climate (in which group members can equally participate to the task), allowing the majority to process the dissenting views extensively

Personality and humor in groups:implications for collective emotional intelligence, psychological safety and satisfaction

Purpose: This study aims to explore the role of team personality and leader’s humor style on the use of humor in group communication and the extent to which group humor mediates the association between team personality on the one hand, psychological safety, collective emotional intelligence and group satisfaction on the other hand. Design/methodology/approach: The authors used a survey to collect data from 304 employees nested in 83 groups working in organizations from various sectors in Romania. Findings: The study results show that extraversion is positively associated with group affiliative humor, while neuroticism has a positive association with group aggressive humor. The leader’s affiliative humor style had a significant positive effect on group affiliative humor, while the effect of leader’s aggressive humor style on the use of aggressive humor in groups was not significant. Furthermore, the authors examined the mediation role of group humor in the relationship between team personality and team emergent states and satisfaction. The authors found that group aggressive humor mediates the association between neuroticism and group emotional intelligence, psychological safety and satisfaction, while affiliative humor mediates the association between extraversion and emotional intelligence and team satisfaction. Originality/value: The study reports one of the first attempts to explore the multilevel interplay of team personality and humor in groups as they relate to emergent states.</p

Affective states and ecological rationality in entrepreneurial decision making

Purpose - The purpose of this paper is to explore the impact of affective appraisal dimensions on the use of two ecologically rational, social heuristics: imitate the majority (IMH) and imitate the best (IBH) during an entrepreneurial strategic decision-making process (ESDM). Design/methodology/approach - The authors test the hypotheses in a controlled field experiment, on a final sample of 98 entrepreneurs. Findings - The study shows that entrepreneurs experiencing affect described by certainty appraisal display a preference for relying on IMH, but not on IBH. Moreover, entrepreneurs who experience unpleasant affect tend to rely more on IMH, rather than IBH. The reverse is true for the entrepreneurs who experience positive affect. Finally, the use of IMH is most likely under unpleasant and certain affect, while the use of IBH is most likely under pleasant and certain affect. Originality/value - The main contribution of this study is that it provides initial support for the impact of affective appraisal dimensions on the use of ecologically rational heuristics (i.e. heuristics that save important resources, but bring beneficial results) during an ESDM process

Power Differences and Dynamics in Multiparty Collaborative Systems:A Systematic Literature Review

This paper presents the results of a systematic literature review on power distribution and power dynamics in multiparty systems. Multiparty systems are underorganized social structures in which power dynamics unfold and impact collaboration effectiveness. We use a theory-driven approach to integrate the empirical literature that explored power differences and dynamics in multiparty systems and we have a two-fold contribution to literature. First, we explore the way power is conceptualized in multiparty systems. Second, we investigate which predictions and propositions of the Social Distance Theory of Power and the Approach Inhibition Model of Power can be used to integrate research on power distribution and dynamics in multiparty systems. We extend the predominantly experimental empirical support of these two theories with insights from the multiparty systems literature. With respect to the way in which power is conceptualized in the multiparty systems literature, our study shows a shift from a possession over resources to a relational perspective on power in the last decades. Moreover, based on the insights of the two psychological theories of power, the study reflects upon the benefits and drawbacks of high versus low power for collaboration effectiveness among stakeholders, pointing towards ways in which facilitators can work with power differences in multiparty systems. Finally, the study points toward directions for future research concerning power dynamics in multiparty systems