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Seawater contains many electrolytes, is abundant in nature, environmentally friendly, and chemically stable, and exhibits substantial potential for replacement of traditional inorganic electrolytes in photoelectrochemical-type photodetectors (PDs). Herein, one-dimensional semiconductor TeSe nanorods (NRs) with core-shell nanostructures were reported, and their morphology, optical behavior, electronic structure, and photoinduced carrier dynamics were systematically investigated. As photosensitizers, the as-resultant TeSe NRs were assembled into PDs, and the influence of the bias potential, light wavelength and intensity, and the concentration of seawater on the photo-response of TeSe NR-based PDs was evaluated. These PDs exhibited favorable photo-response performance upon illumination with light in the ultraviolet-visible-near-infrared (UV-Vis-NIR) range and even simulated sunlight. Moreover, the TeSe NR-based PDs also exhibited a long duration and cycling stability of its on-off switching and might be useful in marine monitoring.

In this work, ultrafast fiber lasers based on 2D selenium-coated tellurium nanosheets in the infrared band are reported. 2D selenium-coated tellurium as a mode locker is shown with broadband saturable absorption and is capable of supporting ultra-stable pulse trains with several hundred-femtosecond pulse widths in the laser cavity. In particular, the as-fabricated 2D selenium-coated tellurium based fiber laser source operating in the communication band (1.5 μm) exhibits the vector pulse property, which supports the study of the vector soliton in ultrafast fiber lasers. The pulse duration of vector solitons is as short as 800 fs. The 2D selenium-coated tellurium is also available for a mode locked fiber laser operating at 1 μm. The laser oscillator has a pulse duration of several picoseconds and the pulse train is ultra-stable after an amplification to 100 mW, which is a promising seed source in the chirped-pulse amplification system in the future.

Inkjet-printing was used to prepare a flexible and transparent humidity sensor with a Ti 3 C 2 /Ag hybrid as the humidity-sensitive film and poly(diallyldimethylammonium chloride) (PDDA) as the adhesive layer. The sensor demonstrates an ultrahigh sensitivity (106 800%), a rapid response (80 ms), and excellent bending resistance. We demonstrate that an array of sensors can track moving fingers in a non-contact way and map the distance of the fingers away from the sensor surface. Therefore, our humidity sensors have great potential for novel human-machine interfacing such as touchless control of electronics and collision control between robots and humans in a cobot setting.

Lead monoxide (PbO), a novel few-layer two-dimensional (2D) material, was theoretically predicted to have an excellent optical response. Herein, the nonlinear optical response of PbO in the infrared region was experimentally investigated. The feasibility of PbO nanosheets as an effective optical saturable absorber was experimentally verified for the first time. Based on the excellent nonlinear optical characteristics, 2D PbO was fabricated as a passive mode locker by depositing onto a fiber patch cord and by decorating on a microfiber, both of which were successfully applied in fiber lasers for the passive mode locking operation. The mode locking pulses of the fiber laser were as short as 650 fs at 1.5 μm. A pulse duration of 5.47 ps with a 1 μm fiber laser was also experimentally verified. Finally, a PbO-decorated microfiber was fabricated as an optical thresholder that can enhance the SNR of a 1 GHz signal up to 6 dB. This finding might facilitate the development of nonlinear photonic devices with high stability and their practical applications in the future.

Tellurium (Te) exhibits many intriguing properties including thermoelectricity, photoelectricity, piezoelectricity, and photoconductivity, and is widely used in detectors, sensors, transistors, and energy devices. Herein, ultrathin two-dimensional (2D) Te nanosheets were fabricated using a facile and cost-effective liquid-phase exfoliation method. Mixing the as-prepared 2D Te nanosheets with polyvinylpyrrolidone (PVP) provided a uniform 2D Te/PVP membrane. The 2D Te/PVP membrane exhibited excellent mechanical properties, thermal properties, and stability. The nonlinear optical properties of the membrane were characterized over the spectral range of 800 to 1550 nm using open-aperture Z-scan technology. A large nonlinear absorption coefficient of about 10-1 cm GW-1 over the whole tested wavelength range demonstrated the efficient broadband saturable absorptivity of the 2D Te/PVP membrane. Using the 2D Te/PVP membrane as a saturable absorber (SA), a highly stable femtosecond laser with a pulse duration of 829 fs in the communication band was obtained. This work highlights the promise of 2D Te/PVP membranes in ultrafast photonics and Te as a new 2D material for use in photonic devices such as all-optical modulators, switches, and thresholds.

Two-dimensional (2D) bismuth(iii) sulfide (Bi 2 S 3 ) nanosheets as non-toxic graphene-like nanomaterials were successfully fabricated by a facile liquid phase exfoliation (LPE) method. A robust photodetector employing a Bi 2 S 3 nanosheet film has been fabricated for the first time via a facile fabrication process on an ITO-coated glass. UV-Vis and Raman spectroscopy techniques were carried out and they confirmed the inherent optical and physical properties of Bi 2 S 3 nanosheets. Photoelectrochemical (PEC) measurements demonstrate that a significantly higher photocurrent density (42 μA cm -2 ) and enhanced photoresponsivity (210 μA W -1 ), at a lower bias potential in alkaline solution, of the Bi 2 S 3 nanosheet-based photodetector are achieved, compared with those of other 2D nanomaterial-based photodetectors under light irradiation. Furthermore, the as-prepared Bi 2 S 3 nanosheet-based photodetector not only exhibits an appropriate capacity of self-driven broadband and high-performance photoresponse but also displays strong long-term stability of the ON/OFF switching behaviour without any external protection in alkaline solutions. Because of facile synthesis via a LPE method, a higher photocurrent density and photoresponsivity, self-driven performance and long-term stability of the Bi 2 S 3 nanosheet-based photodetector at a lower bias potential in alkaline solutions, the present work can provide fundamental acknowledgement of the high performance of this new kind of PEC-type 2D nanosheet-based photodetector.

Here we report a new kind of three-dimensional (3D) hybrid aerogels, based on graphene oxide (GO) and black phosphorus nanoflakes (BPNFs), for the first time. Our results demonstrate that the as-prepared GO/BPNF hybrid aerogels exhibited significantly enhanced photothermal as well as electrical properties of GO aerogels due to the addition of BP. Moreover, they also possessed excellent photothermal stability under ambient conditions without any protection, which can be ascribed to the coverage of BPNFs with GO nanosheets in these aerogels. This exceptional photothermal property along with robust stability renders GO/BPNF aerogels with promising bio-related applications, such as photothermal therapy for cancer treatment.