Simultaneous doping and heterojunction of silver on Na₂Ta₂O₆nanoparticles for visible light driven photocatalysis: the relationship between tunable optical absorption, defect chemistry and photocatalytic activity

Abstract

In this work, we report the synthesis of Na 2 Ta 2 O 6 /Ag heterojunctions with the aim of tailoring their structural, electronic and photocatalytic properties. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, UV-vis optical diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The effects of silver doping and heterojunctions on the electronic structure and photodegradation of a rhodamine B dye solution were investigated experimentally and theoretically. It was found that silver played critical roles in modulating the electronic structure, defect chemistry and visible light photocatalytic activity. Partial incorporation of Ag ions into the Na 2 Ta 2 O 6 host lattice led to a monotonous lattice expansion and introduced an interband for band gap narrowing. Meanwhile, some of the Ag ions were reduced, and crystallized into Ag nanoparticles on Na 2 Ta 2 O 6 surfaces that can promote the visible light absorption efficiency of Na 2 Ta 2 O 6 /Ag heterojunctions. Moreover, the doping and heterojunction of silver can also result in the modulation of defective oxygen species that have a great impact on photocatalytic performance. As a consequence of the well-controlled electronic structure, surface defect chemistry, Ag particle size, BET surface area, and Ag + doping effects, the photocatalytic performance of the Na 2 Ta 2 O 6 /Ag heterojunctions was optimized at an as-measured Ag/Ta molar ratio of 1.17. CrystEngCommThis journal is

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dyes and Colorless Pollutants

“…Three different peaks were found from the curve deconvolution: the energy peaks were found at 529.7, 531.1, and 532.8 eV, which are attributed to lattice oxygen atoms, hydroxyl oxygen, and surface adsorbed oxygen species, respectively. 65,66 The results of XPS confirm the presence of oxygen and hydroxyl species on the surface of the BFO/MXene nanohybrid, which helps in the photocatalytic degradation mechanism; it is a series of redox reactions that occur on the surface of the materials. 67 Figure 3e shows the high-resolution spectrum of Ti 2p, and the peak spreads over 454 to 470 eV, which is attributed to the Ti bond; the binding energies for Ti 2p peak at 459.7 and 465.6 eV for Ti(IV) 2p 3/2 and Ti(IV) 2p 1/2 , respectively.…”

Steering Charge Kinetics of Tin Niobate Photocatalysts: Key Roles of Phase Structure and Electronic Structure

“…In order to trace the effective radical species in the photocatalytic process, a series of controlled experiments by adding corresponding active species scavengers were carried out [69]. Briefly, 0.001 g of benzoquinone (BQ) was added to trap superoxide radical (O 2 −• ), and 0.1 g of ammonium oxalate (AO) was added to trap hole (h + ).…”

One-step controllable synthesis of three-dimensional WO3 hierarchical architectures with different morphologies decorated with silver nanoparticles: enhancing the photocatalytic activity

“…[61][62][63] As a results, these photogenerated electrons (e À ) and electrons from the reservoir on the Ag NPs could be trapped by O 2 molecules in the solution and generate the cO 2 À radical specie. [64][65][66][67] On the other hand, the photogenerated holes (h + ) are capable to react with H 2 O or OH À molecules, generating the cOH radical specie (Scheme 2). As a result, the RhB dye molecules can be effectively photodegraded by these strong oxidants radical species.…”