RESUMO
Photoelectrochemical setups based on semiconductor photoelectrodes are known for their effectiveness in wastewater treatment, powered by solar energy, which is a renewable and sustainable source. These systems require semiconductor photocatalysts with excellent light-absorbing properties and high stability in aqueous environments. In this regard, silicon is highly investigated in solar cells thanks to its narrow bandgap, making it a potential solar harvester. Metal oxides stand as promising semiconductors, which are non-toxic and thermodynamically stable. In this work, two high-efficiency silicon-based cells have been investigated via Solar Cell Capacitance Simulator (SCAPS-1D) software. Thickness and doping concentration, of each layer, have been scrutinized for multiple buffer propositions to investigate the physical feasibility and optimal values allowing maximal light harvesting. It was found that the overall cell performance is influenced by extremely high doping concentrations for some layers. The effect of temperature was investigated as well at temperatures ranging from 300 to 350 K; it was discovered that the cell demonstrates great performance at the ambient temperature. A maximum solar efficiency of about 25.44% was calculated. Our findings build the path towards fabricating highly efficient Si-based solar cells for photoelectrochemical wastewater treatment.
RESUMO
This work was dedicated to the elaboration of new composite materials based on activated carbon and titanium oxide as an ecological solution for the cleaning of water contaminated with pharmaceutical pollutants. Such new composite materials allowed the combining of adsorption and photocatalytic process, which allows a cleaning process that is low cost making them promising materials. The functionalization of the surface of activated carbon (AC) by TiO2 nanoparticles forms the core of the nanocomposite material. This was accomplished using sol-gel process with molar ratios Rn (nTi/nAC) in the range of 1/10 to 7/10 followed by a calcination step (400 °C, N2, 2 h). Using various characterization techniques, AC surface functionalization was confirmed and the formation of a TiO2 coating on the AC was noticed with TiO2 under its unique anatase crystallographic form. The study of adsorption and photocatalytic degradation of the sulfamethazine antibiotic demonstrated that the most photoactive nanocomposite corresponds to the one with Rn = 0.5. Freundlich model was proved to be a perfect fit with the experimental results stating that the adsorption is of multilayer nature on the surface of the adsorbent and with interactions between the pollutants adsorbed on its surface. The photocatalytic degradation of the remaining pharmaceutical pollutant in the solution was evidenced and essentially occurred through the involvement of hydroxyl radicals formed by the excitation of the photocatalyst. The formation of the photoproducts analyzed by the LC/MS technique implies the splitting of the sulfonamide bridge, and by the hydroxylation of the aromatic ring and the pyrimidine group.
