Preparation Of CdTe Based Photoelectroatalysts By Electrochemical Method And Study Of its photoelectrocatalytic Activity

The increasingly serious energy crisis and the environmental contamination have led to an aggressive search for renewable and environmental-friendly alternative energy resources usingphotocatalysts. (1) Metal - chalcogenide nanomaterials, as compared to their wide bandgap counterparts, are particularly attractive photocatalytic materials for the conversion of solar energy into chemical energy under visible-light irradiation. (2)Cadmium telluride (CdTe) is a widely used semiconductor in thin film solar cell modules. Since cadmium telluride is a direct gap semiconductor with a room temperature energy gap of 1.44 eV ,it is considered to be a promising material for low cost thin film photovoltaic andphotoelectrochemical cells. (3)A variety of methods have been employed to prepare CdTe thin films on foreign substrates. CdTe can also be deposited electrochemically. Electrodeposition has advantages such as lowtemperature deposition, low cost of production and high deposit quality. (4)Photocatalytic hydrogen production from water splitting using semiconductor photocatalysts has drawn considerable attention as a promising way of resolving global energy and environmentalproblems. CdTe demonstrate extremely low photocatalytic activity for hydrogen production under visible light. To solve this problem, many approaches have been proposed to enhance the photocatalytic activity of CdTe particles, including the preparation of quantum-sized CdTe anddeposition of noble metals. (5) In the present work, we report on the fabrication and characterization of CdTe thin films on goldsubstrate by electrochemical atomic layer deposition (EC-ALD) method using separate solutions of tellurium dioxide and cadmium sulfate as precursors at room temperature. The amperometric I–t technique is used to fabricate the CdTe film. Therefore, The CdTe- modified indium-tin-oxide (ITO) substrates are prepared by electrochemical - atomic layer deposition (EC-ALD) method at the optimized deposition potential and time. The structural, compositional, morphological properties and photocatalytic activity of thin film photocatalysts were investigated using scanningelectron microscopy (SEM), energy dispersive analysis by X-rays (EDAX) and electrochemical techniques. The SEM images of CdTe optimized thin film reveal the homogeneity of the deposited samples on ITO. The thin films display photocatalytic activity in sodium sulfide solution. We have shownthat the performance of the photocatalysts for hydrogen evolution strongly improved bydeposition of noble metal on the CdTe thin films. This study demonstrates that the amount of the deposited noble metal can be adjusted to obtain a level of activity that is appropriate for the desired photoelectrocatalytic reaction.

کلیدواژه ها:

renewable enregy ، CdTe ، Electrochemical atomic layer deposition (EC-ALD) ، Photoelectrocatalyst ، Hydrogen evolution