MXene has become an emerging two-dimensional layered material of significant interest in the field of photocatalysis. Introducing Ti 3 C 2 -MXene at the semiconductor interface has become a promising strategy for enhancing the photocatalytic performance through charge carrier separation. In this study, a Bi 2 Fe 4 O 9 /1% Ti 3 C 2 (BFT-1) Schottky heterojunction photocatalyst was successfully synthesized to efficiently remove ciprofloxacin (CIP) from water. Under visible-light irradiation for 50 min, the degradation of CIP by BFT-1 reached 85.7% ( k = 0.032 min − 1 ), which was 1.6 times that of the pure Bi 2 Fe 4 O 9 (BFO). The morphological characterization and photoelectrochemical analyses confirmed the successful synthesis of BFT-1. The Schottky heterojunction facilitated electron transfer and inhibited carrier recombination. Meanwhile, the BFT-1/Vis system demonstrated good adaptability to various environmental substrates in water. The BFT-1 photocatalyst also exhibited excellent stability and reusability over multiple cycles, along with minimal metal ion leaching. This research demonstrated the great potential of the BFT-1/Vis system as an efficient solution for the treatment of antibiotic-contaminated wastewater.
Developing efficient and durable oxygen evolution reaction (OER) electrocatalysts for acidic media is crucial for advancing proton exchange membrane water electrolyzers (PEMWEs) but remains highly challenging. In this work, a lattice-engineered Cr-doped Co 3 O 4 (Cr 0.3 -Co 2.7 O 4 ) electrocatalyst is constructed and achieves high activity and robustness for acidic OER. Spectroscopic and theoretical analyses reveal that Cr preferentially substitutes for Co 3+ at octahedral sites to form “CrO 6 ” units, transferring charge from Cr to the coordinated O atoms and activating them as intrinsic proton receptors. This unique functionality enables the formation of a bridged ∗O–O–H–O∗ intermediate, which circumvents the scaling relationship in the adsorbate evolution mechanism and accelerates OER kinetics. Meanwhile, Cr incorporation strengthens neighboring Co–O bonds, preserving structural integrity under acidic conditions. As a result, the Cr 0.3 -Co 2.7 O 4 electrocatalyst delivers an overpotential of 404 mV at 50 mA cm −2 , outperforming commercial IrO 2 (417 mV). In a PEMWE, it delivers 200 mA cm −2 at 1.71 V with 500 h of continuous operation and only 18 μV h −1 degradation. This work establishes lattice engineering of intrinsic proton-accepting motifs as a viable strategy for designing efficient, durable and noble-metal-free electrocatalysts for acidic OER.
Copper (Cu) doping modifies the band structure of TiO 2 by slightly narrowing the bandgap and shifting the Fermi level, while creating localized states that serve as temporary electron reservoirs to suppress rapid carrier recombination. On this basis, a ternary heterojunction Cu–TiO 2 /g-C 3 N 4 (Cu-CT) was constructed by anchoring Cu–TiO 2 onto g-C 3 N 4 nanosheets. The synergistic interaction between Cu-doping and the S-scheme interfacial configuration generates an internal electric field that promotes vectorial carrier migration, enabling electrons in the conduction band of Cu–TiO 2 and holes in the valence band of g-C 3 N 4 . This spatial separation preserves strong redox potentials and markedly suppresses recombination. Consequently, Cu-CT achieves a hydrogen evolution rate of 10.21 mmol g −1 h −1 , more than twenty times higher than pristine TiO 2 . In-situ XPS, KPFM, and DFT analyses collectively validate the S-scheme charge-transfer pathway and highlight the synergistic role of Cu doping with heterojunction engineering, providing mechanistic insights into the rational design of advanced ternary photocatalysts for efficient solar-driven hydrogen production.
Synergistically coupling complementary vacancy pairs with an ultrathin framework provides a promising yet underexplored route to robust photocatalysts for water purification. Herein, we report the synthesis of ultrathin SBBC (Bi 12 SiO 20 –Bi 2 O 3 –BiOCl–Bi 2 SiO 5 )/g-C 3 N 4 (CN) nanosheets (SBCN-6) in which surface [Bi 2+ –V O ] defect centers are deliberately paired with nitrogen vacancies (V N ), thereby uniting dual-defect chemistry with an ultrathin framework. Electron-sequestering [Bi 2+ –V O ] clusters introduce deep trap states, which robustly capture photoexcited electrons generated in SBBC. V N sites in CN serve as efficient electron-trapping centers that significantly suppress internal electron–hole recombination within CN, and this combined action accelerates visible-light redox reactions. This synergistic dual-defect network, comprising [Bi 2+ –V O ] in SBBC and V N sites in CN, significantly enhances charge separation. Density Functional Theory (DFT) and X-ray Photoelectron Spectroscopy (XPS) unveil a type-Z/type-II hybrid transfer cascade: SBBC (V B ) → [Bi 2+ –V O ] → SBBC (C B ) → CN (C B ) ← [V N ] ← CN (V B ). Under visible-light irradiation, the photocatalyst exhibits exceptional activity in degrading refractory antibiotics, achieving a high apparent rate constant (k) of 0.129 min −1 for tetracycline (91.5% degradation in 120 min) and removing 94.3% of ciprofloxacin in 120 min. Moreover, it rapidly degrades the Rhodamine B dye, with over 99% removal within just 30 min. It also retains excellent recyclability over multiple cycles and outperforms most reported Bi-based photocatalysts. Coupling dual-defect engineering with morphology control, this study advances the mechanistic exploration of defect-mediated catalysis and furnishes a valuable reference for constructing visible-light photocatalysts that simultaneously degrade dyes and antibiotics.
