Improved photocatalytic, antimicrobial and photoelectrochemical properties of nanocrystalline Cu2+-doped ZnO nanoparticles
Raksha Umashankar, Seema Devi, K. Gurushantha, S. Manjunatha, M. Al-Dossari, G. Shobha, K.J. Rudresh Kumar, M.R. Suresh Kumar, K. Keshavamurthy, N.S. Abd EL‐Gawaad, A. Madhu, S. Satyanarayana Reddy, N. Srinatha
Abstract
Herein we present the first report on the synthesis of Cu 2+ -doped ZnO nanoparticles via the solution-combustion using a new fuel (Glutamine). Systematic studies were carried out to assess the influence of Cu 2+ -concentration on photocatalytic , antimicrobial, and photoelectrochemical characteristics through various characterizations such as XRD, SEM-EDS, FTIR, UV–Visible, photocatalytic, antimicrobial, photoelectrochemical and Photoluminescence . XRD results show the formation of single-phase nanocrystalline particles and the substitution of Cu 2+ at the Zn 2+ site without the occurrence of impurity phases. SEM & EDS analysis revealed almost spherical particles and nominal (measured and experimental) element compositions . The structural changes induced due to the substitution of Cu 2+ into the ZnO host lattice are evident in FTIR data, which show the presence of stretched ZnO bonds. The band gap narrowing effect was observed up to 5 mol% Cu 2+ and thereafter band gap widens. PL spectra exhibit multiple emission peaks related to defects present in the host ZnO induced by the Cu 2+ & PL intensity increases with the increase of doping concentration up to 3 mol % of Cu 2+ beyond that its decreases with increasing concentration. The prepared NPs demonstrate promising photocatalytic activity against MB dye in both the UV and visible ranges. The maximum 94% percentage degradation was recorded for 9 mol% CuZnO, which is the highest among CuZnO NPs reported to date. In addition, 3 mol% and 2 mol% CuZnO NPs have shown potential antimicrobial activity against Bacillus and Pseudomonas respectively. The possible mechanism for both photocatalytic activity and antimicrobial activity is demonstrated. Furthermore, 5 mol% CuZnO has shown the largest transient photocurrent of 1.147 mA/cm 2 , which is ∼12 times larger than undoped ZnO (0.096 mA/cm 2 ) due to the band-gap narrowing, suggests the possibility of photoelectrochemical sensors.