Nano Research

A method based on the adsorption of ions on the surface of two-dimensional (2D) nanosheets has been developed for photocatalytic CO2 reduction. Isolated Bi ions, confined on the surface of TiO2 nanosheets using a simple ionic adsorption method facilitate the formation of a built-in electric field that effectively promotes charge carrier separation. This leads to an improved performance of the photocatalytic CO2 reduction process with the preferred conversion to CH4. The proposed surface ion-adsorption method is expected to provide an effective approach for the design of highly efficient photocatalytic systems. These findings could be very valuable in photocatalytic CO2 reduction applications.

Hybrid nucleic acid nanostructures partition architectural and functional roles between ribonucleic acid (RNA) joints and deoxyribonucleic acid (DNA) connectors. Nanoshapes self-assemble from nucleic acid modules through synergistic stabilization of marginally stable base pairing interactions within circularly closed polygons. Herein, we report the development of hybrid nanoshapes that include multiple different RNA modules such as internal loop and three-way junction (3WJ) motifs. An iterative mix-and-match screening approach was used to identify suitable DNA connectors that furnished stable nanoshapes for combinations of different RNA modules. The resulting complex multicomponent RNA-DNA hybrid nanoshapes were characterized by atomic force microscopy (AFM) imaging. Our research provides proof of concept for modular design, assembly and screening of RNA-DNA hybrid nanoshapes as building blocks for complex extended nucleic acid materials with features at the sub-10 nm scale.

All-inorganic perovskites, adopting cesium (Cs+) cation to completely replace the organic component of A-sites of hybrid organic–inorganic halide perovskites, have attracted much attention owing to the excellent thermal stability. However, all-inorganic iodine-based perovskites generally exhibit poor phase stability in ambient conditions. Herein, we propose an efficient strategy to introduce antimony (Sb3+) into the crystalline lattices of CsPbI2Br perovskite, which can effectively regulate the growth of perovskite crystals to obtain a more stable perovskite phase. Due to the much smaller ionic radius and lower electronegativity of trivalent Sb3+ than those of Pb2+, the Sb3+ doping can decrease surface defects and suppress charge recombination, resulting in longer carrier lifetime and negligible hysteresis. As a result, the all-inorganic perovskite solar cells (PSCs) based on 0.25% Sb3+ doped CsPbI2Br light absorber and screen-printable nanocarbon counter electrode achieved a power conversion efficiency of 11.06%, which is 16% higher than that of the control devices without Sb3+ doping. Moreover, the Sb3+ doped all-inorganic PSCs also exhibited greatly improved endurance against heat and moisture. Due to the use of low-cost and easy-to-process nanocarbon counter electrodes, the manufacturing process of the all-inorganic PSCs is very convenient and highly repeatable, and the manufacturing cost can be greatly reduced. This work offers a promising approach to constructing high-stability all-inorganic PSCs by introducing appropriate lattice doping.

Over the past few years, the rapid development of tactile sensing technology has contributed significantly to the realization of intuitional touch control and intelligent human-machine interaction. Apart from physical touch or pressure sensing, proximity sensing as a complementary function can extend the detection mode of common single functional tactile sensors. In this work, we present a transparent, matrix-structure dual functional capacitive sensor which integrates the capability of proximity and pressure sensing in one device, and the excellent spatial resolution offered by the isolated response of capacitive pixels enables us to realize precise location identification of approaching objects and loaded pressure with fast response, high stability and high reversibility.

The development of efficient contrast agents for tumor-targeted imaging remains a critical challenge in the clinic. Herein, we proposed a tumor-derived extracellular vesicle (EV)-mediated targeting approach to improve in vivo tumor imaging using ternary downconversion nanoparticles (DCNPs) with strong near infrared II (NIR-II) luminescence at 1,525 nm. The EVs were metabolically engineered with azide group, followed by in vivo labeling of DCNPs through copper-free click chemistry. By taking advantage of the homologous targeting property of tumor derived EVs, remarkable improvement in the tumor accumulation (6.5% injection dose (ID)/g) was achieved in the subcutaneous colorectal cancer model when compared to that of individual DCNPs via passive targeting (1.1% ID/g). Importantly, such bioorthogonal labeling significantly increased NIR-II luminescence signals and prolonged the retention at tumor sites. Our work demonstrates the great potential of EVs-mediated bioorthogonal approach for in vivo labeling of NIR-II optical probes, which provides a robust tool for tumor-specific imaging and targeted therapy.

We report on electrical and optical properties of p+-i-n+ photodetectors/solar cells based on square millimeter arrays of InP nanowires (NWs) grown on InP substrates. The study includes a sample series where the p+-segment length was varied between 0 and 250 nm, as well as solar cells with 9.3% efficiency with similar design. The electrical data for all devices display clear rectifying behavior with an ideality factor between 1.8 and 2.5 at 300 K. From spectrally resolved photocurrent measurements, we conclude that the photocurrent generation process depends strongly on the p+-segment length. Without a p+-segment, photogenerated carriers funneled from the substrate into the NWs contribute strongly to the photocurrent. Adding a p+-segment decouples the substrate and shifts the depletion region, and collection of photogenerated carriers, to the NWs, in agreement with theoretical modeling. In optimized solar cells, clear spectral signatures of interband transitions in the zinc blende and wurtzite InP layers of the mixed-phase i-segments are observed. Complementary electroluminescence, transmission electron microscopy (TEM), as well as measurements of the dependence of the photocurrent on angle of incidence and polarization, support our interpretations.