Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Piotr Warszyński"

Photocatalytic degradation of the organic compounds enhanced by chemical oxidants


  Water for drinking and domestic purposes must not contain harmful substances. It should be transparent, colorless, odorless, have a pleasant and refreshing taste and cannot contain pathogenic bacteria [1]. One of the basic problems of water treatment is the removal of organic species, especially humic substances (HS) - compounds, which have not as yet been properly chemically defined. HS represent a major fraction of natural organic matter (NOM) in ground and surface waters. Their presence causes growth of microorganisms resulting in undesirable odor and change of color and turbidity of water [2]. NOM occurrence in water, especially that part which cannot be removed by coagulation, determines demand for chlorine in chlorination process. However, toxicological studies indicate that after chlorination carcinogenic byproducts, such as trihalomethanes, can be found. Therefore, the efficient removal of NOM leads to reduction of the required amount of disinfectant, decreases the risk of formation trihalomethanes and also prevents the formation of biofilm [3]. For these reasons there exists a strong demand for new methods for NOM removal. As photocatalysis, is a promising method for removing organic compounds from water, in recent years, TiO2 based photocatalysis of humic acids (HAs) has been extensively investigated [4-7]. In this work, the photocatalytic removal of humic acid (HA) under artificial sun light (ASL) and UV irradiation was examined by monitoring changes in the UV absorbance at 254 nm (UV254). That absorbance is the widely accepted measure for determination of the degradation rate of humic acid and is used as the surrogate parameter for the total organic carbon (TOC) - usually applied to determine degree of HA photodegradation [8]. As the alternative method, the measurements of the chemical oxygen demand (COD) were al[...]

The morphology and optical properties of silicon etched with bimetallic catalysts DOI:10.15199/ELE-2014-110


  For the solar cells, which principle of operation is based on the light absorption, every energy loses pose a problem. Namely, reflectivity of the silicon surface used for photovoltaic cell production is one of the factors that needs to be minimized to approach the required absorption properties. The mitigation of the reflectivity is possible in two ways: by the use of an antireflective layer and/or by creation of a specific texture on the silicon surface. Both methods are effective but the texturization shows more advantages. The etching processes with the use of acid or alkaline systems are applied for the latter purpose [1, 2]. Moreover, the wet Metal- Assisted Chemical Etching (MAE) enables control of cross-sectional shape, diameter, length, doping type, doping level and the orientation of silicon nanostructures [3]. It is also possible to accelerate the surface recombination velocity due to increase of the silicon surface area [1]. Additionally, the textured surface allow for absorption of the reflected radiation resulting in an increase of the overall illumination density. The oxidant reduction, which occurs on the surface of metal, is an initial process of MAE. As a result, holes are generated and diffuse through the meta[...]

Wykorzystanie efektu plazmonowego na cząstkach metali do wzbudzenia emisji w konwerterach światła DOI:10.15199/13.2015.8.7


  Niezależnie od stosowanej techniki i wykorzystywanych materiałów, maksymalna wydajność komercyjnych krzemowych ogniw słonecznych nie przekracza 21% [1]. Straty na wydajności krzemowych ogniw fotowoltaicznych wynikają przede wszystkim z absorpcji promieniowania ograniczonego tylko do określonego zakresu widma oraz zjawiska odbicia powierzchniowego. W celu zniwelowania strat wynikających z wyżej opisanych zjawisk wafle krzemowe są teksturyzowane powierzchniowo a także pokrywane materiałami o wysokim współczynniku absorpcji. Unikalne właściwości mechaniczne, duża ruchliwość elektronowa a przede wszystkim znacząco wyższe wydajności ogniw spowodowały, że perowskity hybrydowe o strukturze ogólnej CH3NH3PbX3 (X = anion halogenkowy) są obecnie najbardziej pożądanymi materiałami do zastosowań na krzemowych i organicznych ogniwach słonecznych [2]. Obecnie równie szeroko badany jest wpływ na ogniwa słoneczne cząstek plazmonicznych, szczególnie pod kątem fotoprzewodnictwa [3]. W zależności od kształtu, rozmiaru oraz rodzaju metalicznych nanocząstek, mogą one wykazywać efekt plazmonowy polegający na emisji promieniowa[...]

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