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This work reveals for the first time the underlying mechanism of vacancies in TOMEs and uncovers the effect of atomic-scale polarization on the redox reaction mechanism through in situ Raman and operando ATR-SEIRAS. Further, the stability of cation/anion vacancies is explored in long-term cycling. The findings standardize the fundamentals governing the utility and evolution of vacancies, thereby opening new avenues for a variety of sustainable energy storage schemes.

Abstract

Transition metal oxide electrocatalysts (TMOEs) are poised to revive grid-scale all-vanadium redox flow batteries (VRFBs) due to their low-cost and unique electronic properties, while often inescapably harboring surface vacancies. The role of local vacancy-induced physicochemical properties on vanadium-redox electrochemistry (VRE), encompassing kinetics, and stability, remains profoundly unveiled. Herein, for the first time, it is revealed that vacancies induce atomic-scale polarization in TMOEs and elucidate its mechanism in VRE. Attributable to local polarization, particularly by cation vacancy, the activated nearest-coordinated Mn sites prominently augment the adsorption competence of the V2+/V3+ couple and expedite its round-tripping by forming an intermediate *Mn–O–V bridge. It is also affirmed that the anion vacancies are vulnerable to microstructure reconfiguration by feeble hydroxyl adsorption and thus performance degradation over long-term cycling, in contrast to cation vacancies. Accordingly, the VRFB employing cation-vacancy-functionalized electrode delivers an energy efficiency of 80.8% and a reliable 1000-cycle lifespan with a negligible decay of 0.57% per cycle at 300 mA cm−2, outclassing others. The findings shed light on the fundamental rules governing the utility and evolution of vacancies in TMOEs, thereby moving a step closer toward their deployment in a wide range of sustainable energy storage schemes.

Room-temperature operation or high-operation temperature (HOT) is essential for mid-wave infrared (MWIR) optoelectronics devices providing low-cost and compact systems for numerous applications. A band-engineered mercury telluride colloidal quantum dot (HgTe CQD) heterojunction with suppressed dark current is developed and demonstrates sensitive thermal imaging above 250 K with a resolution of 640 × 512.

Abstract

Room-temperature operation or high-operation temperature (HOT) is essential for mid-wave infrared (MWIR) optoelectronics devices providing low-cost and compact systems for numerous applications. Colloidal quantum dots (CQDs) have emerged as a rising candidate to enable photodetectors to operate at HOT or room temperature and develop the next-generation infrared focal plane array (FPA) imagers. Here, band-engineered heterojunctions are demonstrated to suppress dark current with well-passivated mercury telluride (HgTe) CQDs enabling room-temperature MWIR imaging by single-pixel scanning and 640 × 512 FPA sensitive thermal imaging above 250 K. As a result, the room-temperature detectivity reaches as high as 1.26 × 1010 Jones, and the noise equivalent temperature difference (NETD) is as good as 25 mK up to 200 K.

A method to directly produce structurally colored microparticles by drying cholesteric cellulose nanocrystal microdroplets on a superhydrophobic surface is reported. This approach has several key advantages that can unlock large-scale fabrication of sustainable photonic pigments, including exploiting existing industrial techniques (e.g. aerosolization), reduction in chemicals required (e.g. surfactants), rapid production times (≈40 min or less), and size-independent and robust color.

Abstract

Photonic pigments, especially those based on naturally-derived building blocks like cellulose nanocrystals (CNCs), are emerging as a promising sustainable alternative to absorption-based colorants. However, the proposed manufacturing methods for CNC pigments, via either grinding films or emulsion-based production, usually require several processing steps. This limits their commercialization by increasing the costs, timescales, and environmental impacts of production. Toward addressing these challenges, it is reported that photonic pigments can be produced in a single process by drying microdroplets of aqueous CNC suspension on a superhydrophobic surface. Such liquid-repellent substrate ensures the microdroplets maintain a near-spherical shape, enabling the radial self-organization of the cholesteric phase. Upon drying under ambient conditions, the CNC mesophase becomes kinetically arrested, after which the strong capillary forces induced by water evaporation result in extensive buckling of the microparticle. This buckling, coupled with prior tuning of the CNC formulation, enables photonic pigments with adjustable color across the visible spectrum. Importantly, the elimination of an emulsifying oil phase to create microdroplets enables a much faster drying time (≈40 min) and improved color stability (e.g., polar solvents, elevated temperatures), while the reduction in reagents (e.g., oils, surfactants) and post-processing steps (e.g., solvent, heat) improves the sustainability of the fabrication process.

NaGdF4@PDA-ALD nanoparticles (NPANs) protect mesenchymal stem cells (MSCs) from ischemic stroke by neutralizing reactive oxygen species (ROS) and chelating excess Ca2+. This dual action stabilizes Ca2+ in the endoplasmic reticulum and mitochondria, reduces oxidative stress, and prevents ROS-Ca2+ overload cycles, enhancing MSC survival and functionality, and ultimately improving stroke therapy outcomes.

Abstract

Mesenchymal stem cells (MSCs) transplantation is a promising therapeutic strategy for ischemic stroke. However, the survival of transplanted MSCs is often compromised by the excessive levels of reactive oxygen species (ROS) and calcium ions (Ca2+) in the ischemic microenvironment following blood flow occlusion. In this study, a protective strategy is developed using functional nanomaterials to escort and shield MSCs. Specifically, NaGdF4@PDA-ALD nanoparticles (NPANs) are synthesized, featuring a NaGdF4 core coated with polydopamine (PDA) for ROS scavenging and further modified with alendronate sodium (ALD) for Ca2+ chelation. The internalization of NPANs by MSCs protected them from oxidative damage and calcium overload, thereby promoting their viability and functionality. Furthermore, NaGdF4 generated T1 signal enhancement, enabling in vivo tracking of MSCs via magnetic resonance imaging. The NPANs-treated MSCs demonstrated improved survival and migration to the ischemic region, promoting blood flow restoration and angiogenesis. These findings confirm the feasibility of employing functional nanoparticles to augment MSCs-based therapies, offering a promising strategy to improve their therapeutic efficacy in ischemic stroke treatment.

A photo-adaptive polarization-sensitive organic phototransistor (POL-OPT) based on highly anisotropic organic crystals is developed for bionic night-time polarization perception. Ultrahigh dichroic ratio (DR) of >105 is achieved through time accumulation under ultraweak light of 200 nW cm−2. High-contrast polarization imaging is realized in artificial moonlit environment with a low degree of linear polarization (DoLP) of 0.26, reaching the detection threshold of night-active dung beetles.

Abstract

The emerging semiconductor micro/nanocrystals with intrinsic anisotropy have provided new perspectives for low-cost and simplified polarimetry. However, the low polarization sensitivity of state-of-the-art polarimeters based on anisotropic semiconductors under weak and partially polarized light severely hinders their practical application in complex dim environments. Here, a photo-adaptive polarization-sensitive organic phototransistor (POL-OPT) is demonstrated for bionic weak-light polarization perception. The combination of highly anisotropic organic crystals with charge-storage accumulative effect enables a self-adaptive polarized photoresponse of the phototransistor to imitate the bionic scotopic adaptation process. Consequently, an ultrahigh dichroic ratio (DR) of over 105 is achieved through time accumulation under an ultraweak light intensity of 200 nW cm−2, which is among the highest in polarization-sensitive photodetectors. Furthermore, POL-OPT array is constructed for effective polarization perception in an artificial moonlit environment with a low degree of linear polarization (DoLP) down to 0.26, reaching the detection threshold of night-active dung beetles. This study offers a new opportunity for the development of new-generation high-performance polarimeters for polarization imaging, bionic navigation, and artificial visual systems.

The review covers the past and current developments in light-emitting diodes (LEDs) exploiting nanocrystals of halide perovskites and perovskite-related materials. The review examines the aspects of material optimizations, device engineering, and applications. Furthermore, the current existing challenges and future possible opportunities are discussed in order to define a roadmap in this field of research.

Abstract

Light-emitting diodes (LEDs) based on halide perovskite nanocrystals have attracted extensive attention due to their considerable luminescence efficiency, wide color gamut, high color purity, and facile material synthesis. Since the first demonstration of LEDs based on MAPbBr3 nanocrystals was reported in 2014, the community has witnessed a rapid development in their performances. In this review, a historical perspective of the development of LEDs based on halide perovskite nanocrystals is provided and then a comprehensive survey of current strategies for high-efficiency lead-based perovskite nanocrystals LEDs, including synthesis optimization, ion doping/alloying, and shell coating is presented. Then the basic characteristics and emission mechanisms of lead-free perovskite and perovskite-related nanocrystals emitters in environmentally friendly LEDs, from the standpoint of different emission colors are reviewed. Finally, the progress in LED applications is covered and an outlook of the opportunities and challenges for future developments in this field is provided.

A series of chiral quasi-2D perovskites are reported with efficient circularly polarized luminescence (CPL) in films and circularly polarized electroluminescence (CPEL) in spin-LEDs in the red to near-infrared spectrum region. Spectroscopic studies show that the CPL and CPEL originate from an energy and spin funnel process in the chiral quasi-2D perovskites.

Abstract

Spin light-emitting diodes (spin-LEDs) are important for spin-based electronic circuits as they convert the carrier spin information to optical polarization. Recently, chiral-induced spin selectivity (CISS) has emerged as a new paradigm to enable spin-LED as it does not require any magnetic components and operates at room temperature. However, CISS-enabled spin-LED with tunable wavelengths ranging from red to near-infrared (NIR) has yet to be demonstrated. Here, chiral quasi-2D perovskites are developed to fabricate efficient spin-LEDs with tunable wavelengths from red to NIR region by tuning the halide composition. The optimized chiral perovskite films exhibit efficient circularly polarized luminescence from 675 to 788 nm, with a photoluminescence quantum yield (PLQY) exceeding 86% and a dissymmetry factor (g lum) ranging from 8.5 × 10−3 to 2.6 × 10−2. More importantly, direct circularly polarized electroluminescence (CPEL) is achieved at room temperature in spin-LEDs. This work demonstrated efficient red and NIR spin-LEDs with the highest external quantum efficiency (EQE) reaching 12.4% and the electroluminescence (EL) dissymmetry factors (g EL) ranging from 3.7 × 10−3 to 1.48 × 10−2 at room temperature. The composition-dependent CPEL performance is further attributed to the prolonged spin lifetime as revealed by ultrafast transient absorption spectroscopy.

3D Pillar-layered COFs (PL-COFs) with adjustable interlayer spacing, enhanced crystallinity, and increased porosity are designed and constructed using a pillaring strategy via metal-ligand coordination, which demonstrates significantly improved electrochemical activity and selectivity for CO2-to-CO conversion compared to their 2D layered COF counterparts.

Abstract

Growing global concerns over energy security and climate change have intensified efforts to develop sustainable strategies for electrochemical CO2 reduction (eCO2RR). Covalent Organic Frameworks (COFs) have emerged as promising electrocatalysts for eCO2RR due to their tunable structures, high surface areas, and abundance of active sites. However, the performance of 2D COFs is often limited by layer stacking, which restricts active site exposure and reduces selectivity. To overcome these challenges, a new class of COFs known as pillar-layered COFs (PL-COFs) is developed featuring adjustable interlayer spacing and a 3D architecture. Characterization using PXRD, TEM, XPS, and EIS confirmed the successful integration of pillar molecules, which leads to increased interlayer spacing, crystallinity, and porosity. These structural advancements result in significantly improved electrochemical activity and selectivity for CO2-to-CO conversion. Density functional theory simulations revealed that enhanced CO2 adsorption and CO desorption contribute to the outstanding performance of PL-COF-1, which boasts the largest interlayer spacing. This material achieved an impressive Faradaic efficiency of 91.3% and demonstrated a significant current density, outperforming both the original COF-366-Co and PL-COF-2. These findings highlight the effectiveness of the pillaring strategy in optimizing COF-based electrocatalysts, paving the way for next-generation materials for CO2 reduction and sustainable energy conversion.

Nonlinear ion dynamics in electrochemical ionic synapses enable spike-timing-dependent plasticity (STDP) with low energy consumption and minimal variability. The approach supports diverse STDP forms and flexible learning rules across timescales from milliseconds to nanoseconds, enabling spiking neural network hardware with high throughput and adaptability while maintaining low energy consumption and high reliability.

Abstract

Programmable synaptic devices that can achieve timing-dependent weight updates are key components to implementing energy-efficient spiking neural networks (SNNs). Electrochemical ionic synapses (EIS) enable the programming of weight updates with very low energy consumption and low variability. Here, the strongly nonlinear kinetics of EIS, arising from nonlinear dynamics of ions and charge transfer reactions in solids, are leveraged to implement various forms of spike-timing-dependent plasticity (STDP). In particular, protons are used as the working ion. Different forms of the STDP function are deterministically predicted and emulated by a linear superposition of appropriately designed pre- and post-synaptic neuron signals. Heterogeneous STDP is also demonstrated within the array to capture different learning rules in the same system. STDP timescales are controllable, ranging from milliseconds to nanoseconds. The STDP resulting from EIS has lower variability than other hardware STDP implementations, due to the deterministic and uniform insertion of charge in the tunable channel material. The results indicate that the ion and charge transfer dynamics in EIS can enable bio-plausible synapses for SNN hardware with high energy efficiency, reliability, and throughput.

Printed electronics, with their extensive versatility, resource efficiency, and fast-prototyping capabilities, offer an attractive alternative to Si-based CMOS technology. This paper reviews the recent advances in printed electronics, highlighting emerging printing technologies that could lead to high performance, as well as attributes such as resource efficiency, environmental impact, integration scale, and vertical stack leading to 3D integration.

Abstract

The pursuit of miniaturized Si electronics has revolutionized computing and communication. During recent years, the value addition in electronics has also been achieved through printing, flexible and stretchable electronics form factors, and integration over areas larger than wafer size. Unlike Si semiconductor manufacturing which takes months from tape-out to wafer production, printed electronics offers greater flexibility and fast-prototyping capabilities with lesser resources and waste generation. While significant advances have been made with various types of printed sensors and other passive devices, printed circuits still lag behind Si-based electronics in terms of performance, integration density, and functionality. In this regard, recent advances using high-resolution printing coupled with the use of high mobility materials and device engineering, for both in-plane and out-of-plane integration, raise hopes. This paper focuses on the progress in printed electronics, highlighting emerging printing technologies and related aspects such as resource efficiency, environmental impact, integration scale, and the novel functionalities enabled by vertical integration of printed electronics. By highlighting these advances, this paper intends to reveal the future promise of printed electronics as a sustainable and resource-efficient route for realizing high-performance integrated circuits and systems.

Energy Environ. Sci., 2024, 17,2753-2764
DOI: 10.1039/D3EE04115H, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Thibaut Jousseaume, Jean-François Colin, Marion Chandesris, Sandrine Lyonnard, Samuel Tardif
Developing long-life, high-energy density materials such as the Ni-rich LiNixMnyCozO2 (NMCxyz) is needed to manufacture advanced Li-ion batteries.
The content of this RSS Feed (c) The Royal Society of Chemistry

Energy Environ. Sci., 2024, 17,2566-2575
DOI: 10.1039/D4EE00147H, PaperKaiwen Qi, Pengrui Liang, Shiqiang Wei, Huaisheng Ao, Xuan Ding, Shiyuan Chen, Zhechen Fan, Chengming Wang, Li Song, Xiaojun Wu, Changzheng Wu, Yongchun Zhu
Trade-off between H2O-rich and H2O-poor EDLs to balance dead Zn and dendrites and side reactions, realizing highly reversible Zn anodes.
The content of this RSS Feed (c) The Royal Society of Chemistry

Energy Environ. Sci., 2024, 17,2598-2609
DOI: 10.1039/D3EE04065H, PaperMengting Wang, Tianyi Chen, Yaokai Li, Guanyu Ding, Zeng Chen, Jikun Li, Chang Xu, Adiljan Wupur, Chenran Xu, Yuang Fu, Jingwei Xue, Weifei Fu, Weiming Qiu, Xi Yang, Dawei Wang, Wei Ma, Xinhui Lu, Haiming Zhu, Xiankai Chen, Xiaoye Wang, Hongzheng Chen, Lijian Zuo
This work explores a new solid additive with TADF properties for high-performance OPVs. The TADF additive fine-tunes the morphology and enhances exciton diffusion and dissociation, resulting in an efficiency of 19.4%, making it one of the top binary OPVs.
The content of this RSS Feed (c) The Royal Society of Chemistry

Nature Energy, Published online: 30 January 2025; doi:10.1038/s41560-025-01707-x

Observations of salt formation in CO2 reduction electrolysers were used to propose a mechanism for salt precipitation linked to the drying of liquid droplets carrying cations and (bi)carbonate ions. A hydrophobic surface coating was used to remove droplets from the flow channels before they can dry, increasing the operational stability of the electrolyser.