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The present work explores a solid state route to synthesis of trivalent ions (Eu 3+ , La 3+ , etc.) doped NaTaO 3 with controlled nonstoichiometric chemistry and lattice parameters with an aim to exploring electronic structure and photocatalytic performance. All samples were fully characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption spectrophotometry, UV− vis diffuse reflectance spectroscopy, and photoluminescence measurement. By employing Eu 3+ as a model trivalent ion doped in NaTaO 3 lattice, the effects of siteselective doping and nonstoichiometric chemistry on the lattice parameters, band gap structure, photocatalytic activity toward methylene blue solution, and photocatalytic hydrogen evolution were systematically investigated. A nonstoichiometric Na/Ta molar ratio led to site-selective occupation of Eu 3+ ions which was changed from sole substitution to dual substitutions. Meanwhile, the nonstoichiometric Na/Ta molar ratio and site-selective occupation of Eu 3+ resulted in a monotonous lattice expansion and local symmetry distortion. Lattice variation, doping effects, and its relevant defect chemistry had a great impact on the ν 3 mode vibration of the O−Ta bond, which became asymmetric and shifted toward higher wavenumbers. Moreover, contrary to theoretical predictions, Eu 3+ -doped NaTaO 3 nanocrystals showed an abnormal narrowing of the band gap energies and weak visible light absorption with variation of Na/Ta molar ratios, which is thought to be related to doping effects, defect chemistry, and variation of lattice parameters. With well-defined lattice structure and defect centers and electronic structure via nonstoichiometric control and trivalent ions doping, the photocatalytic activity of trivalent ions-doped NaTaO 3 can be well regulated and optimized.

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A novel direct Z‐scheme CuBi2O4/BiOBr heterostructural photocatalyst was developed aiming to modulate the adsorption ability and photocatalytic degradation performance toward antibiotics. Tetracycline as the model antibiotics was found to show pH value and temperature dependent adsorption capacity over CuBi2O4/BiOBr. The adsorption process was fitted to Pseudo‐second‐order and Elovich kinetic models and adsorption isotherm was followed Freundich isotherm model. Junction of CuBi2O4 and BiOBr can modulate the surface feature and interfacial interactions, leading to direct Z‐scheme charge kinetics for improved photocatalytic activity. The adsorptive capability and photocatalytic performance of CuBi2O4/BiOBr heterojunction showed great improvement in comparison with pristine CuBi2O4 and BiOBr. The mineralization process and intermediates for tetracycline degradation were identified by total organic carbon analysis and liquid chromatograph‐tandem mass spectrometry. Plausible transformation pathway and photocatalytic mechanism were proposed. Radical trapping experiments indicated that photogenerated holes and ⋅O2−active species played crucial roles in photocatalytic tetracycline decomposition.