Two-dimensional (2D) monoelemental bismuth (Bi) crystal, one of the pnictogens (group VA), has recently attracted increasing interest because of its intriguing characteristics. Here, uniformly sized 2D Bi quantum dots (BiQDs) with an average diameter (thickness) of 4.9 ± 1.0 nm (2.6 ± 0.7 nm) were fabricated through a facile liquid-phase exfoliation (LPE) method, and the corresponding photoresponse was evaluated using photoelectrochemical (PEC) measurements. The as-fabricated BiQDs-based photodetector not only exhibits an appropriate capacity for self-driven broadband photoresponse but also shows high-performance photoresponse under low bias potentials ranging from UV to visible light in association with long-term stability of the ON/OFF switching behavior. In terms of these findings, it is further anticipated that the resultant BiQDs possess promising potential in UV–visible photodetection as well as in liquid optoelectronics. Our work may open a new avenue for delivering high-quality monoelemental pnictogen QDs from their bulk counterparts, thereby expanding interest in 2D monoelemental materials.

have also greatly aroused the positive exploration of alternative LIB technologies in recent years. [44] In contrast to the flammable organic electrolyte in LIBs, the aqueous one exhibits lower cost, higher safety, and especially the superior ionic conductivity, which is generally two orders of magnitude higher than that of the organic system. [9,10] All those unparalleled advantages would make the aqueous battery technologies to be the promising candidates in the future. [11] Rechargeable aqueous zinc-ion batteries (AZIBs), which is mainly composed of zinc metal anode, zinc salt-based aqueous electrolyte, and Zn 2+ host cathode, hold the great promise for energy storage applications in very recent years. [12,13] Compared with nonaqueous alkali-ion batteries, the use of cheap and high ambient stable zinc metal anode and inexpensive aqueous electrolyte with superior ionic conductivity (Figure 1a) would make such type of battery to be one of the most promising commercial candidates in the future market. [14-17] To date, extensive studies have been reported for AZIBs, and relating publications have dramatically increased especially in these two years, as shown in Figure 1b. However, the insufficient energy density seems to become the bottleneck that hinder their practical applications at current status. [4,5,18] Such issue could be ascribed to the narrow operating voltage of aqueous electrolyte, insufficient electrochemical performance of cathode materials, and Zn anode. [13,19,20] Besides, the influence of other components such as separator and collector also should be considered to some extent. [20,21] Among them, the studies of widening operating voltage of electrolyte and the optimization of other components only received less attention, which still remain at the early stage. [22,23] On the contrary, more attentions were paid to the electrochemical performance tuning of electrode materials. [24-26] Besides, considering the fixed operating voltage of Zn metal anode, the modification of cathode materials seems to provide more possibilities to effectively improve the energy density of AZIBs, owing to their rich material systems. [20,26,27] Under these considerations, the rational design of advanced cathodes is expected to be a preferential task to develop. Up to now, many types of materials have been exploited as cathode candidates and applied for AZIBs, however, those Rechargeable aqueous zinc-ion batteries (AZIBs) have attracted extensive attention and are considered to be promising energy storage devices, owing to their low cost, eco-friendliness, and high security. However, insufficient energy density has become the bottleneck for practical applications, which is greatly influenced by their cathodes and makes the exploration of high-performance cathodes still a great challenge. This review underscores the recent advances in the rational design of advanced cathodes for AZIBs. The review starts with a brief summary and evaluation of cathode material systems, as well as the introduction of proposed storage mechani...

Tellurium (Te), as one of the rarest stable solid elements far more common in the universe than on earth, is a p‐type semiconductor with excellent optical properties. Herein, a novel two‐dimensional (2D) Te nanosheets (Ns)‐based air‐stable nonlinear photonic devices: all‐optical switcher and photonic diode, owing to its strong light–matter interaction in the visible‐to‐infrared band are reported. The findings validate that the proposed photonic diode can be utilized for the function of nonreciprocal light propagation in optical telecommunications or integrated photonics. Moreover, 2D Te‐based light‐modulate‐light system is successfully designed to realize “ON” and “OFF” modes for all‐optical switching operation. This work highlights a good promise of 2D Te in the field of nonlinear photonics, leading to an important step toward 2D Te‐based advanced photonics devices. The versatile solution process allows a universal access of 2D Te as a new 2D material in a wider range of photonics device applications such as, detector, modulator, switcher, etc.

Graphdiyne is a new carbon allotrope comprising sp‐ and sp2‐hybridized carbon atoms arranged in a 2D layered structure. In this contribution, 2D graphdiyne is demonstrated to exhibit a strong light–matter interaction with high stability to achieve a broadband Kerr nonlinear optical response, which is useful for nonreciprocal light propagation in passive photonic diodes. Furthermore, advantage of the unique Kerr nonlinearity of 2D graphdiyne is taken and a nonreciprocal light propagation device is proposed based on the novel similarity comparison method. Graphdiyne has demonstrated a large nonlinear refractive index in the order of ≈10−5 cm2 W−1, comparing favorably to that of graphene. Based on the strong Kerr nonlinearity of 2D graphdiyne, a nonlinear photonic diode that breaks time‐reversal symmetry is demonstrated to realize the unidirectional excitation of Kerr nonlinearity, which can be regarded as a significant demonstration of a graphdiyne‐based prototypical application in nonlinear photonics and might suggest an important step toward versatile graphdiyne‐based advanced passive photonics devices in the future.

The sluggish sodium reaction kinetics, unstable Sn/Na O interface, and large volume expansion are major obstacles that impede practical applications of SnO -based electrodes for sodium-ion batteries (SIBs). Herein, we report the crafting of homogeneously confined oxygen-vacancy-containing SnO nanoparticles with well-defined void space in porous carbon nanofibers (denoted SnO /C composites) that address the issues noted above for advanced SIBs. Notably, SnO /C composites can be readily exploited as the working electrode, without need for binders and conductive additives. In contrast to past work, SnO /C composites-based SIBs show remarkable electrochemical performance, offering high reversible capacity, ultralong cyclic stability, and excellent rate capability. A discharge capacity of 565 mAh g at 1 A g is retained after 2000 cycles.