Although three-dimensional metal halide perovskite (ABX3) single crystals are promising next-generation materials for radiation detection, state-of-the-art perovskite X-ray detectors include methylammonium as A-site cations, limiting the operational stability. Previous efforts to improve the stability using formamidinium–caesium-alloyed A-site cations usually sacrifice the detection performance because of high trap densities. Here we successfully solve this trade-off between stability and detection performance by synergistic composition engineering, where we include A-site alloys to decrease the trap density and B-site dopants to release the microstrain induced by A-site alloying. As such, we develop high-performance perovskite X-ray detectors with excellent stability. Our X-ray detectors exhibit high sensitivity of (2.6 ± 0.1) × 104 μC Gyair−1 cm−2 under 1 V cm−1 and ultralow limit of detection of 7.09 nGyair s−1. In addition, they feature long-term operational stability over half a year and impressive thermal stability up to 125 °C. We further demonstrate the promise of our perovskite X-ray detectors for low-bias portable applications with high-quality X-ray imaging and monitoring prototypes.

Designing high-performance bifunctional oxygen evolution/reduction reaction (OER/ORR) catalysts is a newly emerged topic with wide applications in metal-air batteries and fuel cells. Herein, we report a group of (27) single-atom...

Two-dimensional (2D) transition-metal carbides (MXenes) as electrode materials have attracted much attention because of their excellent energy storage properties and electrical conductivity. In this work, we study the properties of the V3C2 MXene anode for metal-ion (Li, Na, K, and Ca) batteries by means of density functional theory computations. Based on our calculated results, V3C2 exhibits excellent properties such as structural stability, good electrical conductivity, fast charge–discharge rates, and high theoretical storage capacity. In particular, owing to its low diffusion barrier (0.04 eV for Li, 0.02 eV for Na, 0.01 eV for K, and 0.04 eV for Ca) and high storage capacity (606.42 mA h g–1 for both Li and Na, 269.86 mA h g–1 for K, and 539.71 mA h g–1 for Ca), V3C2 monolayers are predicted to be promising anode materials especially for lithium-ion batteries and sodium-ion batteries. Our work provides a new avenue for the design of novel 2D materials for energy applications.

Despite having attractive stability over the volatile methylammonium (MA) cation, double-cation (Cs, FA) perovskite solar cells are largely overlooked because of their inferior performance compared to MA-based devices. Among all the device engineering strategies, surface passivation represents a promising approach to acquire improved performance. However, effective passivation strategies have not yet been developed for attaining efficiencies of MA-free cells close to their theoretical limit. Herein, fullerene passivators with different binding groups are investigated to establish relationships between molecule structure and perovskite surface properties. It is found that surface treatment with bis-fulleropyrrolidium iodide (bFPI) can have strong interaction with charged defects, leading to effective defect passivation and favorable band-bending at the interface. The resulting bFPI-treated device shows significantly reduced defect density as well as accelerated electron extraction from perovskite into the cathode. Consequently, the MA-free device exhibits an efficiency of 21.1% with long-term environmental stability.

The practical applications of lithium-sulfur (Li–S) batteries are greatly hindered by the poor conductivity of sulfur, the shuttling of lithium polysulfides (LiPSs), and the sluggish kinetics in charge-discharge process. In...

The sodium‐ion battery is a promising battery technology owing to its low price and high abundance of sodium. However, the sluggish kinetics of sodium ion makes it hard to achieve high‐rate performance, therefore impairing the power density. In this work, a fiber‐in‐tube Co9S8‐carbon(C)/Co9S8 is designed with fast sodiation kinetics. The experimental and simulation analysis show that the dominating capacitance mechanism for the high Na‐ion storage performance is due to abundant grain boundaries, three exposed layer interfaces, and carbon wiring in the design. As a result, the fiber‐in‐tube hybrid anode shows a high specific capacity of 616 mAh g−1 after 150 cycles at 0.5 A g−1. At 1 A g−1, a capacity of ca. 451 mAh g−1 can be achieved after 500 cycles. More importantly, a high energy density of 779 Wh kg−1 and power density of 7793 W kg−1 can be obtained simultaneously.

Incentive schemes formed by regulatory or administrative instruments are measures to promote green building (GB) and increase the motivation of developers to meet higher standards. The hidden costs to different stakeholders during the GB transaction are often ignored. Understanding these hidden transaction costs (TCs) helps appraise the costs and benefits of GB and policy effectiveness. The example of a gross floor area (GFA) concession scheme is used systematically to explore and understand the fundamental issues of TCs' typology and chronology in the GB development process. The GFA concession scheme is a popular incentive due to its indirect compensation to developers by allowing additional floor area without expenditure by government to implement GBs. A TCs' framework is used critically to review and evaluate the costs and benefits of the GFA concession scheme. Its particular implementation in both Hong Kong and Singapore is explored. Hong Kong is used as a case study, complemented with in-depth expert interviews on GFA concession in Hong Kong. The key contribution is to establish the parameters for estimating the optimum GFA bonus that could both motivate various stakeholders and minimize the negative impacts on the built environment in future.

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