Non-layered tellurium (Te) is a promising material for applications in transistor and optoelectronic devices for its advantages in excellent intrinsic electronic and optoelectronic properties. However, the poor photodetection performance and relatively uncertain stability of tellurene under ambient conditions greatly limit the practical applications. In order to improve the performance of tellurene-based materials, Te@Se roll-to-roll nanotubes with different selenium (Se) contents synthesized by epitaxial growth of Se on Te nanotubes are, for the first time, employed to fabricate working electrodes for photoelectrochemical (PEC)-type broadband photodetection. They exhibit not only a preferably enhanced capacity for self-powered broadband photodetection but also significantly improved photocurrent density and stability in various aqueous environments (HCl, NaCl, and KOH solutions), compared to tellurene-based photodetectors. It is anticipated that the present work can open up new possibilities for high-performance tellurene-based optoelectronic devices.

Photodynamic therapy (PDT) functions when the light-excited photosensitizers transfer energy to oxygen molecules ( 3 O 2 ) to produce cytotoxic singlet oxygen ( 1 O 2 ) that can effectively kill cells or bacteria. However, the PDT efficacy is often reduced by the limited availability of 3 O 2 surrounding the photosensitizer and extremely short diffusion range of the photoactivated 1 O 2 . Herein, an enzymatic micromotor based on hollow mesoporous SiO 2 (mSiO 2 ) microspheres is constructed as a mobile and highly efficient photosensitizer platform. Carboxylated magnetic nanoparticles are connected with both hollow spheres and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin molecules through covalent linkage between amino and carboxylic groups within a one-step reaction. Due to the intrinsic asymmetry of the mSiO 2 spheres, the micromotors can be propelled by ionic diffusiophoresis induced by the enzymatic decomposition of urea. Via numerical simulation, the self-propulsion mechanism is clarified and the movement direction is identified. By virtue of active self-propulsion, the current system can overcome the long-standing shortcomings of PDT and significantly enhance the PDT efficacy by improving the accessibility of the photosensitizer to 3 O 2 and enlarging the diffusing range of 1 O 2 . Therefore, by proposing a new solution to the bottleneck problems of PDT, this work provides insightful perspectives to the biomedical application of multifunctional micro/nanomotors. applications, including targeted drug delivery, mini-surgery, biochemical sensing, and diagnostics. [13][14][15] In particular, MNMs as active carriers with the capability of cargo loading and controllable motion have great potentials for effective delivery of different types of cargos. [15] So far, researchers have also explored stimuli-responsive materials, [16][17][18][19] biomimetic materials, [20][21][22] and micro-organisms functionalized with nanomaterials [23] as MNMs to precisely transport cargos of drugs, [16,20,23,24] proteins, [18,22,25] and genes [19] in vitro and/or in vivo. Compared with traditional passive delivery, MNMs can perform tasks such as controlled navigation, rapid transportation, and active delivery of payloads to disease sites, and thus have paved way for on demand biomedical cargo transportation. [15] Inspired by these achievements, we envision that self-propelled MNMs can serve as a mobile photosensitizer platform to improve the availability of 3 O 2 as well as the diffusion range of 1 O 2 , which can consequently achieve highly efficient PDT process.

Although theoretical calculations predict vanadium carbide (V2C) MXene may possess superior performances as electrodes of supercapacitors and lithium-ion batteries, a milder synthesis process of high-purity V2C MXene undoubtedly becomes one of the greatest hindrances for extending its applications. Herein, we report a hydrofluoric acid (HF)-free synthesis of 2D V2C MXene by milder etching V2AlC powders in the mixture of lithium fluoride and hydrochloric acid. The etching time plays vital roles on the structure and morphology of V2C MXene. The as-synthesized V2C MXene etched for 120 h displays a uniform multilayered structure and higher purity (>90%). All that matter is it exhibits a maximum specific capacitance of 164 F g−1 at a scan rate of 2 mV s−1, good cycling stability and high specific capacitance retention (~90% after 10 000 cycles at 5 A g−1) in 1 M Na2SO4 electrolyte. Moreover, other fluorides, including potassium fluoride, sodium fluoride and ammonium hydrogen fluoride, are also testified to be effective to obtain highly pure V2C MXene. This work provides the certainty for synthesizing MXenes besides Ti3C2 via a HF-free etching process to beneficially expand their promising application.

No abstract

No abstract