Enhanced photocatalytic activity of hydrogen evolution through Cu incorporated ZnO nano composites. (December 2020)

• Record Type: Journal Article
• Authors: Manzoor, Mian Faisal; Ahmed, Ejaz; Ahmad, Mukhtar; Ahmad, Irshad; Rana, Anwar Manzoor; Ali, Absar; Ghouri, Muhammad Irfan; Manzoor, Mian Sohail; Aziz, Muhammad Tariq
• Is Part Of: Materials science in semiconductor processing. Volume 120(2020)
• Publication Date: 2020-12
• Subjects: Cu doped ZnO -- Structural analysis -- Electrolysis -- Optical properties -- H2 evolution; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2020.105278
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: Green environment friendly and economical light responsive photocatalytic method was used to investigate the improving H2 efficiency of ZnO by Cu doping. Efficient nano composites of ZnO doped with varying percentage of copper (0.0, 0.01, 0.03 and 0.05 mol.%) were synthesized by sol-gel method to analyze H2 evolution. Cu incorporation did not change the hexagonal wurtzite structure of ZnO nanoparticles as examined by x-ray diffraction (XRD). EDX indicates no external trace found in Cu doped ZnO samples and surface area decrease by increasing Cu contents in ZnO proved by BET. Morphology of particles through scanning electron microscopy (SEM) is nearly spherical. Diffuse reflectance spectroscopy (DRS) was utilized to determine the energy band gap (Eg ). Cu incorporation into ZnO decreased energy band gap from 3.19 eV to 3.00 eV. XPS shows electronic state of nanoparticles. Recombination rate of photo induced electrons and holes analyzed by photoluminescence spectroscopy (PL) decreased by increase in Cu doping percentage. Further the reduced recombination rate was examined by electrochemical impedance spectroscopy (EIS) and photocurrent density. EIS and photocurrent density are in good affiliation with photoluminescence results. Cu incorporated ZnO catalysts caused an enhancement in H2 production from 7.49 μmol g -1 to 41.55 μmol g -1 . Such improvement in H2 production by Cu doped ZnO nanoparticles is due to the reduced recombination of electrons and holes during photocatalytic reaction. Highlights: H2 evolution investigated for Cu1-x Znx O nanoparticles catalysts through splitting of water-methanol solution by photochemical reaction. XRD confirmed the hexagonal wurtzite structure of ZnO not changed upon Cu doping. DRS and PL investigated the decrease band gap and enhance charge separation respectively upon Cu doping. EDX, BET and XPS verified the surface properties and chemical composition. The decrease of EIS and increase in photocurrent by increasing Cu contents is in consensus with PL results. Reduced band gap, large charge separation, verified chemical composition and surface area, reduced EIS and increasing current density are all the results which show the enhanced hydrogen production.