Investigation on Oxygen vacancy mediated Ceria based photocatalytic materials for energy and environmental sustainability

Abstract

newlineNano ceria and its derivatives are promising photocatalysts for environmental newlinesustainability due to their strong redox ability, high oxygen storage/release capacity, ecofriendly, newlinephotostable and cost-effective nature. This dissertation highlights the first prepared newlineN/S co-doped ceria by simple hydrothermal method from Ce (NO)3 and thiourea source. newlineThe spectroscopic, crystallographic and macroscopic features of the synthesised newlinephotocatalysts were well characterised by TEM, UV-vis DRS, PL, TRPL, XRD, Raman and newlinephotoelectrochemical measurements. Under visible light illumination doped ceria exhibits newlineremarkable photocatalytic activity towards Cr(VI) reduction compared to neat CeO2. The newlineenhanced photoreduction ability of doped CeO2, particularly 36 h treated sample (NCS-36) newlineis due to more light absorption capacity, greater photocurrent generation and high newlineconcentration of photoexcited electron, which were well supported by performed newlinecharacterization techniques. The average lifetime decay of photoexcited electrons and newlinephotocurrent density of NCS-36 was found to be 75.37 ps and 3.87 mA/cm2 which is nearly newline3 and 12 times higher than neat ceria, respectively. These results clearly explain the 93% newlinephotoreduction ability of NCS-36 towards 50 ppm Cr (VI) solution within a time-lapse of newline120 min under visible light irradiation. newlineFigure 1: Enhanced visible light harnessing and oxygen vacancy promoted N, S codoped newlineCeO2 nanoparticle: A challenging photocatalyst for Cr(VI) reduction newlinevi newlineA series of Fe-doped CeO2 nanoparticles were synthesised by simple coprecipitation newlinetechnique by varying the dopant concentration (0 and#8805; 5%)for photocatalytic newlinewater decomposition under visible light irradiation. The prepared photocatalysts were newlinecharacterized by crystallographic, microscopic and spectroscopic methods to investigate the newlinecause of their robust photocatalytic activity. The pattern suggests the formation of a highly newlinecrystalline face-centred cubic-fluorite structure of as-synthesized nanoparticles. The doping newlineamount of Fe in CeO2 lattice strongly affects the bandgap of neat CeO2 (CF0) and shift it newlinefrom UV to Visible region i.e. 3.0 eV to 1.85 eV. The successful doping of Fe in CeO2 newlinelattice resulted in the formation new dopant energy levels that facilitate interfacial charge newlinetransfer of both electrons (e-) and holes (h+) for better photoredox reaction of water under newlinevisible light irradiation. Further, BET surface area measurement, PL, TRPL and newlinephotoelectrochemical analyses reveals that presence of Fe3+ ion in ceria lattice causes an newlineenhancement of the surface area, low PL intensity, longer average decay time (value of and#10216;and#964;and#10217; newlinefor CF0 and CF3 is 2.13 and 4.16 ns, respectively) and high photocurrent generation. The newlineCF3 sample exhibits 31 times more current generation than CF0 and showed the highest newlineamount of hydrogen production i.e. 641 and#956;mol/h with an apparent conversion efficiency of newline9.13%. newlineFigure 2: Enhanced Photocatalytic activity of Nanostructured Fe doped CeO2for newlineHydrogen Production under visible light irradiation newlineIn the present study, a series of Ce2Zr2O7atrGO nanocomposites were synthesized newlineby a simple solution combustion method followed by photoreduction technique. The asprepared newlinesamples were well diagnosed by various analytical techniques towards