Bandgap engineering approach for designing CuO/Mn3O4/CeO2 heterojunction as a novel photocatalyst for AOP-assisted degradation of Malachite green dye

A ternary nanohybrid CuO/Mn₃O₄/CeO₂ was developed in the present work using a co-precipitation-assisted hydrothermal method. The designed photocatalyst's structural, morphology, elemental composition, electronic states of elements, and optical properties were studied using corresponding analytical techniques. Results from PXRD, TEM/HRTEM, XPS, EDAX, and PL showed that the desired nanostructure had formed. Using Tauc's energy band gap plot, it was determined that the nanostructures band gap was ~ 2.44 eV, which showed the band margins of the various moieties, CeO₂, Mn₃O₄, and CuO, had modified. Thus, improved redox conditions led to a substantial decrease in the recombination rate of electron-hole pairs, which was further explained by a PL study in that charge separation plays a key role. Under exposure to visible light irradiation for 60 min, it was revealed that the photocatalyst achieved 98.98% of photodegradation efficiency for malachite green (MG) dye. The process of photodegradation proceeded according to a pseudo-first-order reaction kinetic model with an excellent rate of reaction of 0.07295 min^-1 with R² = 0.99144. The impacts of different reaction variables, inorganic salts, and water matrices were investigated. This research seeks to create a ternary nanohybrid photocatalyst with high photostability, visible spectrum activity, and reusability up to four cycles.

Novel CuO/Mn3O4/ZnO nanocomposite with superior photocatalytic activity for removal of Rabeprazole from water

In this work, a nanohybrid of CuO/Mn3O4/ZnO was generated through a simple hydrothermal based procedure. The CuO/Mn3O4/ZnO nanohybrid has been characterized using X-ray diffraction, transmission electron microscopy high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. UV-visible spectrophotometry and photoluminescence techniques allowed evaluation of optical properties that additionally suggested the prevalence of strong interfacial interaction between the three moieties of the nanohybrid and suppressed electron-hole recombination. The hybrid photocatalyst brought on ~ 97.02 ± 1.15% disintegration of rabeprazole when illuminated with visible light. The progress of the photodegradation was in conformity with pseudo-first order kinetic model and had a velocity constant of 0.07773 min-1. Additionally, ~ 84.45% of total organic carbon removal was achieved while chemical oxygen demand was reduced by ~ 73.01%. Using high resolution liquid chromatograph mass spectrometry technique, identification of the degraded products was made and accordingly the mechanistic route of the aforesaid degradation was proposed.

Challenges in Determining the Location of Dopants, to Study the Influence of Metal Doping on the Photocatalytic Activities of ZnO Nanopowders

Impurity doping is one of the common approaches to enhance the photoactivity of semiconductor nanomaterials by increasing photon-capture efficiency in the visible light range. However, many studies on the doping effects have produced inconclusive and conflicting results. There are some misleading assumptions and errors that are frequently made in the data interpretation, which can lead to inconsistent results about the doping effects on photocatalysis. One of them is the determination of the location of dopants. Even using advanced analytical techniques, it is still challenging to distinguish between bulk modification and surface modification. The paper provides a case study of transition-metal-doped ZnO nanoparticles, whereby demonstrating common pitfalls in the interpretation of the results of widely-used analytical methods in detail, and discussing the importance of using a combination of many characterization techniques to correctly determine the location of added impurities, for elucidating the influence of metal doping on the photocatalytic activities of semiconductor nanoparticles.

Structure-retentive synthesis of a highly ordered mesoporous Nb2O5/N-doped graphene nanocomposite with superior interfacial contacts and improved visible-light photocatalysis

A highly ordered mesoporous Nb₂O₅/N-doped graphene nanocomposite was constructed for efficient photocatalytic H₂ evolution under irradiation of visible light.

Synthesis of mesoporous SiO2/Cu2O–graphene nanocomposites and their highly efficient photocatalytic performance for dye pollutants

A mesoporous SiO₂/Cu₂O–graphene composite, a novel material, was successfully synthesized using a self-assembly method with tetraethyl orthosilicate (TEOS).

Facile preparation of a novel SnO2@UiO-66/rGO hybrid with enhanced photocatalytic activity under visible light irradiation

An effective ternary composite of SnO₂@UiO-66/rGO was designed and synthesized.

A facile hydrothermal method for the controllable synthesis of TiO2 nanocrystals with tunable shapes

Using OA and OM as the capping surfactants, a facile and harmless hydrothermal method was invented to prepare anatase TiO₂ nanocrystals with exposed {101} facets.