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Overcoming the self-corrosion and surface passivation of aluminum anode, and the slow kinetics of cathodic electrochemical reactions are of great significance for the practical application of aluminum–air battery. In this study, we replaced the traditional aqueous electrolyte with AlCl 3 -urea ionic liquid electrolyte, and prepared Co–MnO 2 /C catalysts as cathode catalyst. Structures and electrocatalytic activity of the x % Co–MnO 2 /C (x is the mole percent of Co to Mn, x = 0, 10, 20, 30, 40 and 50) catalysts have been investigated systematically. After Co ions intercalation, the specific surface area of the catalyst increased and average pore diameter decreased. The unique interaction between Co ions and MnO 2 led to an increase in the catalytic activity of the catalyst in the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) compared with MnO 2 /C. In particular, 40% Co–MnO 2 /C showed the largest specific surface area (154.25 m2 g−1) and the smallest average pore diameter (6.47 nm). It showed the most positive half-wave potential (0.727 V vs. RHE) and the biggest limiting current density (4.744 mA cm−2) in ORR process, and also exhibited the lowest onset potential (1.593 V) and the biggest limit current density (15.177 mA cm−2) in OER process. Furthermore, aluminum–air battery assembled with 40% Co–MnO 2 /C demonstrated excellent reversible charge and discharge performance, which had an average discharge voltage of 1.5 V and an average charge voltage of 2 V during 30 cycles at a limited battery capacity of 375 mAh g−1. Our results reveal the possibility of designing a rechargeable aluminum-air battery working at ambient conditions based on the Co–MnO 2 /C air cathode catalyst for the first time. Our work opens up a new way to achieve the rechargeability of aluminum-air batteries, and our highly active electrocatalytic materials can be used in a wider range of electrochemical energy applications. Co–MnO 2 /C catalysts were prepared by intercalating Co ions between MnO 2 layers, the unique interaction between Co ions and MnO 2 led to an increase in the catalytic activity of the catalysts in ORR/OER process compared with MnO 2 /C, and the aluminum–air battery assembled with 40% Co–MnO 2 /C catalyst and AlCl 3 -urea ionic liquid electrolyte demonstrated excellent reversible charge and discharge performance. Image 1 • A novel Co–MnO 2 /C catalyst was successfully prepared by intercalating Co ions between MnO 2 layers. • The unique interaction between Co ions and MnO 2 led to an increase in the catalytic activity of the catalyst. • 40% Co–MnO 2 /C as air cathode catalyst exhibited the best ORR/OER catalytic activity. • A button-type rechargeable aluminum-air battery working at ambient conditions was designed for the first time. • As-prepared aluminum-air battery demonstrated excellent reversible charge and discharge performance. [ABSTRACT FROM AUTHOR]

Lead halide perovskite solar cells (PSCs) have attracted intensive attention since their power conversion efficiency (PCE) increased sharply in recent years. Thereinto, triple cation perovskite (TCP) is a popular light absorption layer for PSCs due to its excellent thermal and humidity stability. However, a large amount of MA+ (≥15%) and Br- (≥15%) in TCP makes the bandgap widen drifting from the optimum value. There is some extent of a trade-off between PCE and stability for PSCs, and narrow-bandgap TCP is one of the best choices for light absorption material to achieve an optimum balance between PCE and stability. Herein, we prepared a narrow-bandgap (1.56 eV) high-quality TCP (Cs 0.05 FA 0.86 MA 0.09 Pb(I 0.97 Br 0.03) 3) film with an average grain size up to 1208 nm and corresponding PSC with high efficiency of 20.8%. Moreover, the intermediate process of the TCP film crystallization was carefully studied disclosing the critical α-Phase intermediate and corresponding roles of DMSO solvent and MACl additive through quasi-in-situ XRD in the film formation process, and the results may give critical clues to the fabrication of high-quality narrow-bandgap TCP based PSCs. • High-quality FAPbI3-based TCP film with a narrow-bandgap (1.56 eV) was successfully prepared by applying the α-phase intermediate strategy: the grain size of the film can reach 1208 nm and the carrier lifetime exceeds 3 μs. • The crytical intermediate process introduced by the synergy of DMSO and MACl was disclosed through quasi-in-situ XRD in the film formation process. • The solar cells based on the low-doping FAPbI 3 -based TCP films show high performance and good stability even without surface passivation. [ABSTRACT FROM AUTHOR]