AgBr Nanocrystals from Plates to Cubes and Their Photocatalytic Properties

Boosting photocatalytic performances of lamellar BiVO4by constructing S-scheme heterojunctions with AgBr for efficient charge transfer

Successful construction of heterojunction can improve the utilization efficiency of solar light by broadening the absorption range, facilitating charge-carrier separation, promoting carrier transportation and influencing surface-interface reaction. Herein, visible-light-driven AgBr was deposited on the surface of lamellar BiVO₄which was prepared by a facile hydrothermal process to improve charge carrier separation, and subsequent photocatalytic effectiveness. The catalyst with an optimal AgBr/BiVO₄ratio exhibited a superbly enhanced photocatalytic decolorization ability (about 6.85 times higher than that of pure BiVO₄) and high stability after four cycles. The unique photocatalytic mechanism of S-scheme carrier migration was investigated on the bases of radical trapping tests and photo/electrochemical characterizations. Results showed that the enhanced migration strategy and intimately interfacial collaboration guaranteed the effective charge carriers separation/transfer, leading to magnificent photocatalytic performance as well as excellent stability.

Mesoporous TiO2 with WO3 functioning as dopant and light-sensitizer: A highly efficient photocatalyst for degradation of organic compound

The suitable doping or modification on TiO₂ holds promise for improving charge separation and extending light absorption range. Here, WO₃ modifying reduced band gap mesoporous TiO₂ (WO₃/RM-TiO₂) due to WO₃ doping was successfully fabricated by immersing mesoporous TiO₂ nanoparticles in the peroxotungstic acid sol with controllable reaction time (0-1 h). The W⁶⁺ ions were first incorporated into the TiO₂ lattice to form WOTi bonds, resulting in the formation of WO₃ doping TiO₂. Then, WO₃ nanoparticles gradually formed and attached on the TiO₂ surface, constructing a novel heterojunction catalyst with WO₃ serving as both dopant and light-sensitizer for TiO₂. Photocatalytic activity of the resulting WO₃/RM-TiO₂ depends on the immersing duration in the peroxotungstic acid. The BET analysis shows that 0.5 h-WO₃/RM-TiO₂ has the largest pore volume of 0.491 cm³ g^-1 and the highest surface area of 82.3 m² g^-1, whereas these values decline with prolonged immersing duration. As expected, the optimal efficiency in removing p-nitrophenol (PNP) is achieved over 0.5 h-WO₃/RM-TiO₂ under visible light irradiation, which is 2.33 times that of the unmodified M-TiO₂. This should be attributed to the suitable WO₃ doping and WO₃ modification.

Shape-dependent thermo-plasmonic effect of nanoporous gold at the nanoscale for ultrasensitive heat-mediated remote actuation

Nanoporous gold (NPG) promises efficient light-to-heat transformation, yet suffers limited photothermal conversion efficiency owing to the difficulty in controlling its morphology for the direct modulation of thermo-plasmonic properties. Herein, we showcase a series of shape-controlled NPG nanoparticles with distinct bowl- (NPG-B), tube- (NPG-T) and plate-like (NPG-P) structures for quantitative temperature regulation up to 140 °C in <1 s using laser irradiation. Notably, NPG-B exhibits the highest photothermal efficiency of 68%, which is >12 and 39 percentage points better than those of other NPG shapes (NPG-T, 56%; NPG-P, 49%) and Au nanoparticles (29%), respectively. We attribute NPG-B's superior photothermal performance to its >13% enhanced light absorption cross-section compared to other Au nanostructures. We further realize an ultrasensitive heat-mediated light-to-mechanical "kill switch" by integrating NPG-B with a heat-responsive shape-memory polymer (SMP/NPG-B). This SMP/NPG-B hybrid is analogous to a photo-triggered mechanical arm, and can be activated swiftly in <4 s simply by remote laser irradiation. Achieving remotely-activated "kill switch" is critical in case of emergencies such as gas leaks, where physical access is usually prohibited or dangerous. Our work offers valuable insights into the structural design of NPG for optimal light-to-heat conversion, and creates opportunities to formulate next-generation smart materials for on-demand and multi-directional responsiveness.

Integrating AgI/AgBr biphasic heterostructures encased by few layer h-BN with enhanced catalytic activity and stability

Using freshly prepared water-soluble KBr crystal as facile, low-cost sacrificial template, AgBr nanocubes were synthesized through one-pot precipitation method, then navy bean shaped AgI/AgBr biphasic heterostructures were synthesized through anion-exchange reaction and encased within few-layer h-BN to obtain final product. The obtained heterostructured AgI/AgBr/h-BN composite without plasmonic noble metal nanoparticles was used as stable and high active photocatalyst for dye degradation under visible light irradiation, comparing both with self-prepared normal AgBr, AgBr cubes, AgI/AgBr navy beans and other related catalysts reported in the literature. The significant boosting of activity was attributed to the formation of AgI/AgBr interface and the coupling of few-layer h-BN, the latter of which not only effectively suppresses the reduction of silver ions but greatly enhance the charge separation. Furthermore, it was suggested that the photogenerated holes and superoxide radical were the main active species according to photoelectron chemical measurements, electron spin resonance spin-trap analysis and radical trapping experiments. Finally, the possible mechanism of enhanced photocatalytic activity and stability was discussed and proposed. The work demonstrates that engineering Ag-based semiconductor coupling with h-BN would profit the design strategy for low-cost, solar-driven photocatalysts.

Sheet-like and truncated-dodecahedron-like AgI structures via a surfactant-assisted protocol and their morphology-dependent photocatalytic performance

Sheet-like and truncated-dodecahedron-like AgI structures are synthesized via a surfactant-assisted method, the latter display boosted photocatalytic performances and excellent recyclability.

Fabrication of AgBr nanomaterials as excellent antibacterial agents

The excellent disinfection properties of AgBr nanocubes are due to the “dual-punch” of Ag ions induced disturbance to bio-function and AgBr nanocube-induced damage to cellular structure.

Facile synthesis of one dimensional AgBr@Ag nanostructures and their visible light photocatalytic properties

In this work, we successfully prepared one dimensional (1D) AgBr@Ag nanostructures in high yield by a facile wet chemical method, and the plausible growth mechanism was discussed. The synthesis of as-prepared AgBr@Ag nanostructure is a dissolution and recrystallization process, and the PVP and DMSO have a synergistic and competitive effect on the preparation of 1D AgBr@Ag products. Moreover, the AgBr@Ag nanorods exhibit excellent photocatalytic activities under visible light illumination, which may be attributed to their large surface area as well as superior charge separation and transfer efficiency compared to AgBr@Ag particles.