One-dimensional (1D) nanostructures of perovskite piezoelectrics exhibit unique properties that distinct them from those of their bulk and thin-film counterparts. These 1D nanostructures feature cantilever-like flexibility and elasticity, a relatively high piezoelectric constant, good stability and easiness of integration, making them highly promising for applications in energy harvesting, pressure sensing, piezo-catalysis, nano-actuators and smart human-machine interfaces. Among them, (K,Na)NbO₃ (KNN) has been regarded as one of the most promising lead-free perovskite piezoelectrics owing to its excellent biocompatibility, good piezoelectric performance, and high Curie temperature. Recently, significant efforts have been made to develop high-performance 1D KNN nanostructures (1D KNNs). However, the controllable growth and enhancement in piezoelectric performance of 1D KNNs remain challenging. In this work, we systematically re-examine the effective approaches for the growth of 1D KNNs and explore their unique properties. Key strategies for structural designs and performance optimization are proposed based on the recent progress, along with perspectives in developing novel functionalities and micro/nano-devices such as energy harvesters, information storage, electronic skins, biomedical applications.

Sodium-ion-based electrochromic device (SECD) has been identified as an appealing cost-effective alternative of lithium-based counterparts, only if it can address the challenges in association with the inadequate electrochromic performance. In this regard, the quantized strategy is a particularly promising approach owing to the large surface-to-volume ratio and high reaction activity. However, quantum dots inevitably suffer from volume changes and undesired aggregation during electrochemical cycling. Herein, bioinspired from the robust connection of alveoli in lung, we propose a stable electrode, where WO₃ quantum dots (WQDs) are robustly anchored on Ti₃C₂ MXene through the strong chemical bonds of W-O-Ti. Theoretical results reveal the fundamental mechanism of the volume changes within WQDs and the dynamic diffusion process of sodium ions. The WQD@MXene electrodes exhibit a nearly twofold enhancement in cycling performance (1000 vs 500 cycles), coloration speed (3.2 vs 6.0 s), and areal capacity (87.5 vs 43.9 mAh m⁻² at 0.1 mA cm⁻²), compared to those of the pristine WQD electrode. As a proof-of-concept demonstration, a smart house system integrated with SECDs demonstrates a “3-in-1” device, enabling a combination of energy-saving, energy storage, and display functionalities. The present work significantly advances the versatile applications of cost-effective electrochromic electronics in interdisciplinary.

Transition metal diselenides are promising electrocatalysts for hydrogen evolution and therefore different approaches have been proposed to enhance their catalytic activity. Herein, we describe systematic studies of the dependence of transition-metal doping on the catalytic activity of NiSe₂ by first principles calculations, where Fe is demonstrated to be the best candidate element to tune the electrocatalytic activity of NiSe₂ with lower ΔG_H* values and increased electrical conductivity. To provide further experimental evidence, Fe-doped NiSe₂ porous nanosheets grown on carbon cloth are successfully developed. These nanosheets show significantly improved efficiency for hydrogen evolution reactions compared to their un-doped counterpart. The optimized Ni_0.8Fe_0.2Se₂ electrocatalyst gives rise to a current density of 10 mA·cm^-2 at a very low overpotential of 64 mV with outstanding long-term stability. The present strategy of doping NiSe₂ -based electrocatalysts with transition metals paves a new pathway for the design and synthesis of electrocatalysts for large-scale electrochemical energy applications.