TODAY, WATER CONSERVATION IS VERY IMPORTANT, AND METHODS THAT HELP TO REMOVE WATER POLLUTION IS INCREASING. IN THIS STUDY, DECOMPOSITION OF CONGO RED DYE POLLUTANTS IN TEXTILE WASTEWATER HAS BEEN STUDIED BY USING MODERN METHODS OF PHOTOELECTROCHEMISTRY. OPERATING CONDITIONS, INCLUDING PH, CONCENTRATION POLLUTANTS, TEMPERATURE, APPLIED ELECTRICAL CURRENT INTENSITY, WAS OPTIMIZED. POLLUTANT CONCENTRATIONS15 PPM, PH=7, TEMPERATURE=35OC AND I=90 MA FOR OPTIMUM CONDITIONS OF DECOMPOSITION OF CONGO RED DYE POLLUTANTS WERE DETERMINED.

INTRODUCTION: CNTS AND TITANIUM DIOXIDE (TIO2) COMPOSITE (CNTS/TIO2) MATERIALS ARE A WIDELY USED IN MANY DIFFERENT AREAS SUCH AS WATER TREATMENT, HETEROGENEOUS PHOTOCATALYSIS, PHOTOELECTROCATALYSIS, CO2 PHOTO REDUCTION, HYDROGEN EVOLUTION, DYE SENSITIZED SOLAR CELLS AND SENSOR DEVICES [1, 2]. THE CNTS/TIO2 COMPOSITES HAVING A HIGH SURFACE AREA SHOWED AN EXCELLENT PHOTOCATALYTIC/PHOTOELECTROCATALYTIC PROPERTIES [3]. THE COMBINATION OF CNTS WITH TIO2 CAN IMPROVE THE PHOTOCATALYTIC ACTIVITY OF TIO2 AND THE SEPARATION OF THE ELECTRON–HOLE CHARGES GENERATED UPON IRRADIATION [1, 4].

A THIN SILVER LAYER DEPOSITED ON A CONDUCTING SUPPORT OF TIO2 PHOTOCATALYZES THE OXIDATION AND REDUCTION OF WATER TO O2 AND H2. THE LIGHT SENSITIVITY IN THE VISIBLE PART OF THE SPECTRUM IS DUE TO SELF-SENSITIZATION CAUSED BY REDUCED SILVER SPECIES. ANODIC POLARIZATION REOXIDIZES THE REDUCED SILVER SPECIES. TO TEST ITS WATER SPLITTING CAPABILITY, SILVER COATED-TIO2 PHOTOANODES WERE EMPLOYED IN THE ANODIC PART OF A SETUP FOR PHOTOELECTROCHEMICAL WATER SPLITTING CONSISTING OF PLATINUM FOIL FOR CATHODE AND AG/AGCL AS A REFERENCE ELECTRODE. ILLUMINATION OF THE PHOTOANODE LED TO PHOTOELECTROCHEMICAL WATER SPLITTING TO O2 AND H2. SILVER COATED- TIO2 PHOTOANODES INCREASED PHOTOCURRENT, AND CONSEQUENTLY A HIGHER O2 AND H2 PRODUCTION, WERE OBSERVED.

A THIN SILVER LAYER DEPOSITED ON A CONDUCTING SUPPORT OF TIO2 PHOTOCATALYZES THE OXIDATION AND REDUCTION OF WATER TO O2 AND H2. THE LIGHT SENSITIVITY IN THE VISIBLE PART OF THE SPECTRUM IS DUE TO SELF-SENSITIZATION CAUSED BY REDUCED SILVER SPECIES. ANODIC POLARIZATION REOXIDIZES THE REDUCED SILVER SPECIES. TO TEST ITS WATER SPLITTING CAPABILITY, SILVER COATED-TIO2 PHOTOANODES WERE EMPLOYED IN THE ANODIC PART OF A SETUP FOR PHOTOELECTROCHEMICAL WATER SPLITTING CONSISTING OF PLATINUM FOIL FOR CATHODE AND AG/AGCL AS A REFERENCE ELECTRODE. ILLUMINATION OF THE PHOTOANODE LED TO PHOTOELECTROCHEMICAL WATER SPLITTING TO O2 AND H2. SILVER COATED- TIO2 PHOTOANODES INCREASED PHOTOCURRENT, AND CONSEQUENTLY A HIGHER O2 AND H2 PRODUCTION, WERE OBSERVED.

IN THE LAST FEW DECADES, NANOSTRUCTURED SEMICONDUCTING MATERIALS HAVE ATTRACTED SIGNIFICANT ATTENTION IN SCIENCE AND TECHNOLOGY BECAUSE OF THEIR OUTSTANDING OPTICAL AND ELECTRICAL PROPERTIES AND EXTENSIVELY POTENTIAL APPLICATIONS IN DIFFERENT AREAS, INCLUDING MICROELECTRONICS, ELECTROOPTICS, PHOTOCATALYSIS, PHOTOELECTROCHEMISTRY, ENERGY CONVERSION AND BIOLOGICAL IMAGING [1, 2].AMONG THE SEMICONDUCTING MATERIAL, PBS IS A WELL-KNOWN P–P SEMICONDUCTOR WITH CUBIC CRYSTAL STRUCTURE AND NARROW BANDGAP (0.41 EV AT 300 K). LEAD SULFIDE HAVING A LARGE EXCITON BOHR RADIUS (18 NM) SHOWS STRONG QUANTUM-SIZE EFFECTS IN NANOCRYSTALLINE FORM AND HAS BEEN WIDELY USED IN OPTOELECTRONIC DEVICES [3, 4].IN THIS WORK, WE HAVE SUCCESSFULLYREPORTED A SIMPLE, CLEAN, CHEAP AND TEMPLATE-FREE SYNTHESIS ROUTE OF WELL-DEFINED PBS NANOSTRUCTURES VIA NEW PRECIPITATION METHOD USING PB (CH3COO) 2.3H2O AS A PRECURSOR AND THIOUREA AS A SULFUR SOURCE UNDER ALKALINE MEDIA. THIS EXPERIMENTS WERE PERFORMED IN TWO DIFFERENT TEMPERATURES (ROOM TEMPERATURE AND 70OC) AND IN THE PRESENCE OF SURFACTANT ORSURFACTANT-FREE CONDITIONS. THE STRUCTURE AND MORPHOLOGY OF AS-PREPARED PBS NANOSTRUCTURES WERECHARACTERIZED BY X-RAY DIFFRACTION (XRD), FIELD EMISSION SCANNING ELECTRON MICROSCOPY (FESEM) AND PHOTOLUMINESCENCE SPECTROSCOPY.

PHOTO ELECTROCHEMICAL HYDROGEN PRODUCTION FROM WATER SPLITTING UNDER VISIBLE-LIGHT IRRADIATION IS CONSIDERED TO BE AN ATTRACTIVE WAY TO SOLVE THE INCREASING GLOBAL ENERGY CRISIS AND ENVIRONMENTAL POLLUTION IN MODERN LIFE [1-3]. PHOTOELECTROCHEMISTRY (PEC) IS THE MOST PROMISING SYSTEM TO SUSTAINABLY PRODUCE HYDROGEN FUEL .IN THIS STUDY, THE PECH2-PRODUCTION ACTIVITY OVER THE REDUCED GRAPHENE OXIDE/ZNXCD1-XS NANOCOMPOSITES UNDER SIMULATED SOLAR IRRADIATION HAS BEEN REPORTED. AT FIRST, THE ELECTROPHORETIC METHOD WAS APPLIED TO DEPOSIT CHEMICALLY SYNTHESIZED GRAPHENE OXIDE (GRO) NANOSHEETS ONTO A TITANIUM MESH AS A SUITABLE SUBSTRATE. DURING THE ELECTROPHORETIC DEPOSITION, GRO IS REDUCED TO REDUCED GRAPHENE OXIDE (RGO). THEN, BY USING A FEASIBLE CO-PRECIPITATION HYDROTHERMAL STRATEGY, RGO-ZNXCD1-XS PHOTOANODE WAS SYNTHESIZED. IN THIS WAY, GRAPHENE/TITANIUM MESH WAS PLACED IN AN OUTOCLAVE INCLUDED CERTAIN AMOUNTS OF THIOUREA, ZN(NO3)2 AND CD(NO3)2. FOR OBTAINING HIGH EFFICIENCY IN H2 PRODUCTION, THE EXPERIMENTAL CONDITIONS SUCH AS REAGENTS RATIO, REACTION TEMPERATURE AND TIME WERE EXAMINED UNDER THE OPTIMIZED CONDITIONS (INCLUDING ZN: CD RATIO OF 4:1, THE REACTION TEMPERATURE OF 180OC, AND THE REACTION TIME OF 24H) ZNXCD1-XS NANOCOMPOSITE WERE DEPOSITED ON RGO/TI .THE PHOTO ELECTROCHEMICAL MEASUREMENTS WERE CARRIED OUT USING A GALVANOSTAT/POTENTIOSTAT AUTOLAB PGSTAT101 INSTRUMENT AND A THREE-ELECTRODE ELECTROCHEMICAL CELL WITH RGO-ZNXCD1-XS PHOTOANODE AS A WORKING ELECTRODE, A PLATINUM PLATE AS A COUNTER ELECTRODE, AND A AG/AGCL (KCL 3.0 M) AS A REFERENCE ELECTRODE. A HIGH-INTENSITY XE LAMP WITH UV FILTER WAS USED AS THE SOURCE OF THE VISIBLE LIGHT IRRADIATION. DURING ALL MEASUREMENTS, 0.1 M NA2SO4 WAS USED AS ELECTROLYTE. THE PHOTOCURRENT RESPONSE OF THE RGO-ZN0.8CD0.2S NANOCOMPOSITE PHOTOANODE WERE RECORDED 1.5 MA UNDER THE APPLIED POTENTIAL OF 0.5 V WITH SWITCHING-ON AND -OFF MODEL. THE PHOTOCURRENTS OF ZNXCD1-XS WERE ALTERED BY VARYING THE ZN/CD RATIO. IT WAS OBTAINED THAT UNDER THE SAME EXPERIMENTAL CONDITIONS, RGO-ZN0.8CD0.2S NANOCOMPOSITE WITH HIGHER PHOTOCURRENT HAS HIGHER EFFICIENCY IN H2 PRODUCTION.