Rechargeable zinc-air batteries (RZABs) are considered one of the most promising candidates for advanced energy storage and conversion in the near future. The RZABs’ efficiency is closely tied to the performances of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) occurring at the air cathode. Metal-oxide catalysts occupy a crucial role in reducing the reaction energy barriers and improving the ORR and OER performance. Two types of metal-oxide electrocatalysts used in RZABs are single-metal active-site (SMAS) and dual-metal active-site (DMAS) oxides, both of which significantly impact the efficiency and durability of ORR and OER. This review presents a comprehensive analysis of the advancements in SMAS and DMAS, especially single-phase DMAS oxides, offering significant insights into the design of high-performance bifunctional oxygen electrocatalysts and RZABs.

High-performance cooling technology is increasingly critical due to the rising frequency of extremely hot weather caused by global warming. Passive daytime radiative cooling (PDRC) is an emerging zero-energy-consumption technology that provides sub-ambient cooling under strong solar conditions by emitting heat to the cold outer space (~ 3 K) while minimizing heat gain from solar irradiation. This technology has attracted wide attention and achieved huge progress in the past decade. Recently, extensive efforts have been devoted to constructing high-performance PDRC materials in various fields, such as thermal management of buildings, human comfort, equipment, and dynamic devices. However, there is still a big gap between the laboratory-reported PDRC materials and their practical applications because of their high costs, complex manufacturing processes, insufficient cooling performance, and potential nano- or micro-hazards. In this review, we summarized recent advancements in PDRC technology and focused on the spectral design, cooling mechanisms, and practical applications of PDRC materials. We also discussed the challenges and strategies for bridging the gap between academic research and real-world implementation. We hope that this review will provide more insight into the further development of advanced PDRC technologies.

Prussian blue (PB), as a promising inorganic electrochromic material (ECM), has been widely used in smart windows, displays, sensors, etc. However, there are still many challenges for PB to achieve high electrochromic performance. Herein, we synthesized nitrogen-doped carbon dots-modified PB film (defined as PB@N-CDs) with a sandwich-like structure by a simple stepwise electrodeposition method. The carbon dots show an obvious advantage in ultrafast electron transfer ability, which can reduce charge loss during the transfer process, improve the electrochemical activity on both sides of PB, and thus facilitate a rapid electrochromic response. Furthermore, the surface of nitrogen-doped carbon dots contains multiple organic functional groups, which widen the movement path of K⁺ ions under electrostatic adsorption. Impressively, the PB@N-CDs film exhibits a short bleaching/coloring time (0.5/0.9 s) and a superior optical modulation range (78.6%). Particularly, the coloring efficiency has been significantly improved to 137.71 cm²/C (at 700 nm). All of these results open up new avenues for developing high-performance PB-based ECMs and promoting their applications in corresponding electrochromic devices (ECDs) and smart windows.

Electrochromic smart windows have attracted much attention in energy-saving buildings because of their ability to selectively modulate visible (VIS) and near-infrared (NIR) light transmittance. As is known, the NIR region accounts for about 50% of the total solar radiation. Therefore, reducing the NIR transmittance of windows will play a crucial role in reducing the energy consumption of buildings. However, for most of the reported electrochromic materials (ECMs)-based windows, it remains a long-lasting challenge about how to achieve a low NIR transmittance during the past decades. In this work, we synthesize oxygen-deficient tungsten oxide (WO_3−x) nanoflowers (NFs) by a simple and efficient method that is facile for their mass production. The WO_3−x NFs exhibit low NIR transmittance of only 4.11%, 0.60%, and 0.19% at 1200, 1600, and 1800 nm, respectively, due to the localized surface plasmon resonance (LSPR) effect. Besides, the WO_3−x NFs exhibit an excellent dual-band modulating ability for both VIS and NIR light. They are able to operate in three distinct modes, including a bright mode, a cool mode, and a dark mode. Moreover, the WO_3−x NFs exhibit a fast bleaching/coloring time (1.54/6.67 s), and excellent cycling stability (97.75% of capacity retention after 4000 s).