g-C3N4/Ca2Fe2O5 heterostructures for enhanced photocatalytic degradation of organic effluents under sunlight

Abstractg-C3N4/Ca2Fe2O5 heterostructures were successfully prepared by incorporating g-C3N4 into Ca2Fe2O5 (CFO). As prepared g-C3N4/CFO heterostructures were initially utilized to photodegrade organic effluent Methylene blue (MB) for optimization of photodegradation performance. 50% g-C3N4 content in CFO composition showed an enhanced photodegradation efficiency (~ 96%) over g-C3N4 (48.15%) and CFO (81.9%) due to mitigation of recombination of photogenerated charge carriers by Type-II heterojunction. The optimized composition of heterostructure was further tested for degradation of Bisphenol-A (BPA) under direct sunlight, exhibiting enhanced photodegradation efficiency of about 63.1% over g-C3N4 (17%) and CFO (45.1%). The photoelectrochemical studies at various potentials with and without light illumination showed significant improvement in photocurrent response for g-C3N4/Ca2Fe2O5 heterostructures (~ 1.9 mA) over CFO (~ 67.4 μA). These studies revealed efficient solar energy harvesting ability of g-C3N4/Ca2Fe2O5 heterostructures to be utilized for organic effluent treatment.

Photosensitive Thin Films Based on Drop Cast and Langmuir-Blodgett Hydrophilic and Hydrophobic CdS Nanoparticles

Comparative photoelectrochemical studies of cadmium sulfide (CdS) nanoparticles with either hydrophilic or hydrophobic surface properties are presented. Oleylamine organic shells provided CdS nanoparticles with hydrophobic behavior, affecting the photoelectrochemical properties of such nanostructured semiconductor. Hydrophilic CdS nanoparticles were drop-cast on the electrode, whereas the hydrophobic ones were transferred in a controlled manner with Langmuir-Blodgett technique. The substantial hindrance of photopotential and photocurrent was observed for L-B CdS films as compared to the hydrophilic, uncoated nanoparticles that were drop-cast directly on the electrode surface. The electron lifetime in both hydrophilic and hydrophobic nanocrystalline CdS was determined, revealing longer carrier lifetime for oleylamine coated CdS nanoparticles, ascribed to the trapping of charge at the interface of the organic shell/CdS nanoparticle and to the dominant influence of the resistance of the organic shell against the flux of charges. The “on” transients of the photocurrent responses, observed only for the oleylamine-coated nanoparticles, were resolved, yielding the potential-dependent rate constants of the redox processes occurring at the interface.

Photoelectrochemical Behavior of the Ternary Heterostructured Systems CdS/WO3/TiO2

In this article, we report the results of comparative studies of photoelectrochemical behavior of the binary CdS/TiO2 and WO3/TiO2 and ternary CdS/WO3/TiO2 heterostructures based on titania nanotube and planar structures. Physical–chemical characterization by XRD, XPS, and electron microscopy methods together with electrochemical impedance spectroscopy measurements confirm a successful formation of heterostructured electrodes, both nanotube-based and planar. The results of photoelectrochemical studies of the heterostructures demonstrate a significant difference in their behavior depending on the structure geometry and the character of the formed heterojunctions. It is concluded that nanotube-based heterostructure electrodes can be characterized by a stochastic set of different heterojunctions while planar systems demonstrate well-ordered heterojunctions with a strictly defined electron transfer direction. Particularly, we demonstrate the possibility of the realization of Z-scheme of photoexcitation and charge separation in ternary planar systems under visible light irradiation.