A negative capacitance (NC) effect has been proposed as a critical pathway to overcome the 'Boltzmann tyranny' of electrons, achieve the steep slope operation of transistors and reduce the power dissipation of current semiconductor devices. In particular, the ferroic property in hafnium-based films with fluorite structure provides an opportunity for the application of the NC effect in electronic devices. However, to date, only a transient NC effect has been confirmed in hafnium-based ferroic materials, which is usually accompanied by hysteresis and is detrimental to low-power transistor operations. The stabilized NC effect enables hysteresis-free and low-power transistors but is difficult to observe and demonstrate in hafnium-based films. This difficulty is closely related to the polycrystalline and multi-phase structure of hafnium-based films fabricated by atomic layer deposition or chemical solution deposition. Here, we prepare epitaxial ferroelectric Hf_0.5Zr_0.5O₂ and antiferroelectric ZrO₂ films with single-phase structure and observe the capacitance enhancement effect of Hf_0.5Zr_0.5O₂/Al₂O₃ and ZrO₂/Al₂O₃ capacitors compared to that of the isolated Al₂O₃ capacitor, verifying the stabilized NC effect. The capacitance of Hf_0.5Zr_0.5O₂ and ZrO₂ is evaluated as −17.41 and −27.64 pF, respectively. The observation of the stabilized NC effect in hafnium-based films sheds light on NC studies and paves the way for low-power transistors.

The tremendous efforts made in the research field of solid-state Li-ion batteries have led to considerable advancement of this technology and the first market-ready systems can be expected in the near future. The research community is currently investigating different solid-state electrolyte classes (e.g. oxides, sulfides, halides and polymers) with a focus on further optimizing the synthesis and electrochemical performance. However, so far, the development of sustainable recycling strategies allowing for an efficient backflow of critical elements contained in these batteries into the economic cycle and thus a transition from a linear to a circular economy lags behind. In this contribution, resource aspects with respect to the chemical value of crucial materials, which are used for the synthesis of solid-state electrolytes are being discussed. Furthermore, an overview of possible approaches in relation to their challenges and opportunities for the recycling of solid-state batteries with respect to different solid-state electrolyte classes by means of pyrometallurgy, hydrometallurgy and direct recycling/dissolution-based separation processes is given. Based on these considerations and with reference to previous research, it will be shown that different solid-state electrolytes will require individually adapted recycling processes to be suitably designed for a circular economy and that further improvements and investigations will be required.

In recent years, zinc-ion batteries (ZIBs) have been considered one of the most promising candidates for next-generation electrochemical energy storage systems due to their advantages of high safety, high specific capacity and high economic efficiency. As an indispensable component, the electrolyte has the function of connecting the cathode and the anode, and plays a key role in the performance of the battery. Different types of electrolytes have different effects on the performance of ZIBs, and the use of additives has further developed the research on modified electrolytes, thus effectively solving many serious problems faced by ZIBs. Therefore, to further explore the improvement of ZIBs by electrolyte engineering, it is necessary to summarize the current status of the design of various electrolyte additives, as well as their functions and mechanism in ZIBs. This paper analyzes the challenges faced by different electrolytes, reviews the different solutions of additives to solve battery problems in liquid electrolytes and solid electrolytes, and finally makes suggestions for the development of modified ZIB electrolytes. It is hoped that the review and strategies proposed in this paper will facilitate development of new electrolyte additives for ZIBs.

Owing to the capability of the conversion between thermal energy and electrical energy and their advantages of light weight, compactness, noise-free operation, and precision reliability, wearable thermoelectrics show great potential for diverse applications. Among them, weavable thermoelectrics, a subclass with inherent flexibility, wearability, and operability, find utility in harnessing waste heat from irregular heat sources. Given the rapid advancements in this field, a timely review is essential to consolidate the progress and challenge. Here, we provide an overview of the state of weavable thermoelectric materials and devices in wearable smart textiles, encompassing mechanisms, materials, fabrications, device structures, and applications from recent advancements, challenges, and prospects. This review can serve as a valuable reference for researchers in the field of flexible wearable thermoelectric materials and devices and their applications.

Detecting light from a wealth of physical degrees of freedom (e.g., wavelength, intensity, polarization state, phase, etc.) enables the acquirement of more comprehensive information. In the past two decades, low-dimensional van der Waals materials (vdWMs) have established themselves as transformative building blocks toward lensless polarization optoelectronics, which is highly beneficial for optoelectronic system miniaturization. This review provides a comprehensive overview on the recent development of low-dimensional vdWM polarized photodetectors. To begin with, the exploitation of pristine 1D/2D vdWMs with immanent in-plane anisotropy and related heterostructures for filterless polarization-sensitive photodetectors is introduced. Then, we have systematically epitomized the various strategies to induce polarization photosensitivity and enhance the degree of anisotropy for low-dimensional vdWM photodetectors, including quantum tailoring, construction of core-shell structures, rolling engineering, ferroelectric regulation, strain engineering, etc., with emphasis on the fundamental physical principles. Following that, the ingenious optoelectronic applications based on the low-dimensional vdWM polarized photodetectors, including multiplexing optical communications and enhanced-contrast imaging, have been presented. In the end, the current challenges along with the future prospects of this burgeoning research field have been underscored. On the whole, the review depicts a fascinating landscape for the next-generation high-integration multifunctional optoelectronic systems.

The integration of sensory information from different modalities, such as touch and vision, is essential for organisms to perform behavioral functions such as decision-making, learning, and memory. Artificial implementation of human multi-sensory perception using electronic supports is of great significance for achieving efficient human–machine interaction. Thanks to their structural and functional similarity with biological synapses, memristors are emerging as promising nanodevices for developing artificial neuromorphic perception. Memristive devices can sense multidimensional signals including light, pressure, and sound. Their in-sensor computing architecture represents an ideal platform for efficient multimodal perception. We review recent progress in multimodal memristive technology and its application to neuromorphic perception of complex stimuli carrying visual, olfactory, auditory, and tactile information. At the device level, the operation model and undergoing mechanism have also been introduced. Finally, we discuss the challenges and prospects associated with this rapidly progressing field of research.

Recently, off-centering behavior has been discovered in a series of thermoelectric materials. This behavior indicates that the constituent atoms of the lattice displace from their coordination centers, leading to the locally distorted state and local symmetry breaking, while the material still retains its original crystallographic symmetry. This effect has been proved to be the root cause of ultralow thermal conductivity in off-centering materials, and is considered as an effective tool to regulate the thermal conductivity and improve the thermoelectric performance. Herein, we present a collection of recently discovered off-centering compounds, discuss their electronic origins and local coordination structures, and illuminate the underlying mechanism of the off-centering effect on phonon transport and thermal conductivity. This paper presents a comprehensive view of our current understanding to the off-centering effect, and provides a new idea for designing high performance thermoelectrics.

Conversion/alloying materials (CAMs) represent a potential alternative to graphite as a Li-ion anode active material, especially for high-power applications. So far, however, essentially all studies on CAMs have been dealing with nano-sized particles, leaving the question of how the performance (and the de-/lithiation mechanism in general) is affected by the particle size. Herein, we comparatively investigate four different samples of Zn_0.9Co_0.1O with a particle size ranging from about 30 nm to a few micrometers. The results show that electrodes made of larger particles are more susceptible to fading due to particle displacement and particle cracking. The results also show that the conversion-type reaction in particular is affected by an increasing particle size, becoming less reversible due to the formation of relatively large transition metal (TM) and alloying metal nanograins upon lithiation, thus hindering an efficient electron transport within the initial particle, while the alloying contribution remains essentially unaffected. The generality of these findings is confirmed by also investigating Sn_0.9Fe_0.1O₂ as a second CAM with a substantially greater contribution of the alloying reaction and employing Fe instead of Co as a TM dopant.

Proton exchange membrane (PEM) water electrolysis represents a promising technology for green hydrogen production, but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts, especially iridium (Ir) based materials for the energy-demanding oxygen evolution reaction (OER). Herein, we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel (Ni) oxy-hydroxide supported on antimony-doped tin oxide (ATO) nanoparticles (IrNi_yO_x/ATO, 20 wt.% (Ir + Ni), y = 0, 1, 2, and 3), aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER performance. When tested in strongly acidic electrolyte (0.1 M HClO₄), the optimised IrNi₁O_x/ATO shows a mass activity of 1.0 mA µg_Ir⁻¹ and a large turnover frequency of 123 s⁻¹ at an overpotential of 350 mV, as well as a comparatively small Tafel slope of 50 mV dec⁻¹, better than the IrO_x/ATO control, particularly with a markedly reduced Ir loading of only 19.7 µg_Ir cm⁻². Importantly, IrNi₁O_x/ATO also exhibits substantially better catalytic stability than other reference catalysts, able to continuously catalyse acidic OER at 10 mA cm⁻² for 15 h without obvious degradation. Our in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir³⁺/Ir⁴⁺ species are the active sites for the acidic OER. Furthermore, the performance of IrNi₁O_x/ATO was also preliminarily evaluated in a membrane electrode assembly, which shows better activity and stability than other reference catalysts. The IrNi₁O_x/ATO reported in this work is a promising alternative to commercial IrO₂ based catalysts for PEM electrolysis.

Amorphous Ga₂O₃ (a-Ga₂O₃) has been attracting more and more attention due to its unique merits such as wide bandgap (∼4.9 eV), low growth temperature, large-scale uniformity, low cost and energy efficient, making it a powerful competitor in flexible deep ultraviolet (UV) photodetection. Although the responsivity of the ever-reported a-Ga₂O₃ UV photodetectors (PDs) is usually in the level of hundreds of A/W, it is often accompanied by a large dark current due to the presence of abundant oxygen vacancy (V_O) defects, which severely limits the possibility to detect weak signals and achieve versatile applications. In this work, the V_O defects in a-Ga₂O₃ thin films are successfully passivated by in-situ hydrogen doping during the magnetron sputtering process. As a result, the dark current of a-Ga₂O₃ UV PD is remarkably suppressed to 5.17 × 10⁻¹¹ A at a bias of 5 V. Importantly, the photocurrent of the corresponding device is still as high as 1.37 × 10⁻³ A, leading to a high photo-to-dark current ratio of 2.65 × 10⁷ and the capability to detect the UV light with the intensity below 10 nW cm⁻². Moreover, the H-doped a-Ga₂O₃ thin films have also been deposited on polyethylene naphtholate substrates to construct flexible UV PDs, which exhibit no great degradation in bending states and fatigue tests. These results demonstrate that hydrogen doping can effectively improve the performance of a-Ga₂O₃ UV PDs, further promoting its practical application in various areas.