Mixed-dimension van der Waals (vdW) p–n heterojunction photodiodes have inspired worldwide efforts to combine the excellent properties of 2D materials and traditional semiconductors without consideration of lattice mismatch.

Biomimetic eyes, with their excellent imaging functions such as large fields of view and low aberrations, have shown great potentials in the fields of visual prostheses and robotics. However, high power consumption and difficulties in device integration severely restrict their rapid development. In this study, an artificial synaptic device consisting of a molybdenum disulfide (MoS2) film coated with an electron injection enhanced indium (In) layer is proposed to increase the channel conductivity and reduce the power consumption. This artificial synaptic device achieves an ultralow power consumption of 68.9 aJ per spike, which is several hundred times lower than those of the optical artificial synapses reported in literature. Furthermore, the multilayer and polycrystalline MoS2 film shows persistent photoconductivity performance, effectively resulting in short‐term plasticity, long‐term plasticity, and their transitions between each other. A 5 × 5 In/MoS2 synaptic device array is constructed into a hemispherical electronic retina, demonstrating its impressive image sensing and learning functions. This research provides a new methodology for effective control of artificial synaptic devices, which have great opportunities used in bionic retinas, robots, and visual prostheses.

Atomically thin hexagonal boron nitride (h‐BN) is an emerging star of 2D materials. It is taken as an optimal substrate for other 2D‐material‐based devices owing to its atomical flatness, absence of dangling bonds, and excellent stability. Specifically, h‐BN is found to be a natural hyperbolic material in the mid‐infrared range, as well as a piezoelectric material. All the unique properties are beneficial for novel applications in optoelectronics and electronics. Currently, most of these applications are merely based on exfoliated h‐BN flakes at their proof‐of‐concept stages. Chemical vapor deposition (CVD) is considered as the most promising approach for producing large‐scale, high‐quality, atomically thin h‐BN films and heterostructures. Herein, CVD synthesis of atomically thin h‐BN is the focus. Also, the growth kinetics are systematically investigated to point out general strategies for controllable and scalable preparation of single‐crystal h‐BN film. Meanwhile, epitaxial growth of 2D materials onto h‐BN and at its edge to construct heterostructures is summarized, emphasizing that the specific orientation of constituent parts in heterostructures can introduce novel properties. Finally, recent applications of atomically thin h‐BN and its heterostructures in optoelectronics and electronics are summarized.

Mesocrystals are of great interest for a wide range of applications owing to their unique structural features and properties. The realization of well-defined metal oxide mesocrystals through a facile and green synthetic approach still remains a great challenge. Here, a novel synthesis strategy is reported for the production of spindle-shaped anatase TiO mesocrystals with a single-crystal-like structure, which was simply achieved through the one-step hydrolysis reaction of TiCl in the green and recyclable media polyethylene glycol (PEG-400) without any additives. Such anatase mesocrystals were constructed from small nanocrystal subunits (≈1.5-4.5 nm in diameter) and formed through oriented aggregation of the nanocrystals pre-formed in the reaction system. Owing to their novel structural characteristics, the as-synthesized anatase mesocrystals could be easily fused in situ into porous single crystals by annealing in air. More significantly, after being annealed in vacuum, Ti sites could be easily induced in the anatase crystal lattice, resulting in the formation of Ti self-doped anatase mesocrystals. The thus-transformed mesocrystals exhibited enhanced visible light activity towards the photocatalytic oxidation of nitric oxide (NO) to NO , which could be largely attributed to their intrinsic Ti self-doped nature, as well as high crystallinity and high porosity of the mesocrystalline architecture.

Effective control of electrical and optoelectronic properties of two-dimensional layered materials, one of the key requirements for applications in advanced optoelectronics with multiple functions, has been hindered by the difficulty...