In recent years, lead halide perovskites have been widely used as appealing candidates in solar energy conversion. However, further development of these materials is restricted by their instability and toxicity. Therefore, searching for efficient lead-free perovskites with excellent photoelectric properties is highly anticipated. We report a postsynthesis visible light irradiation on Cs2AgBiBr6 to form a defect-rich Cs2AgBiBr6 via inducing surface defects in Cs2AgBiBr6. The formation of surface defects can promote surface charge separation by tuning the local atomic arrangement and electronic structure and optimizing the surface structure, thereby boosting the photocatalytic efficiency of the defect-rich Cs2AgBiBr6. The photocatalytic hydrogen evolution efficiency is enhanced by about 5.27, 5.51, and 5.48 times compared to the bulk Cs2AgBiBr6, Cs2AgBiBr6/Pt, and Cs2AgBiBr6/Mo3S13 2–, respectively. This defect-rich Cs2AgBiBr6 presents strong stability with no performance decrease even after an 80 h photocatalytic reaction. These findings provide an accessible strategy for preparing highly efficient and stable lead-free perovskites.

No abstract

No abstract

Metals are widely used, from daily life to modern industry. Great efforts have been made to protect the metals with various coatings. However, the well-known conventional electrochemical corrosion induced by cations and the ubiquitous nature of the coffee-ring effect make these processes very difficult. Here, a scheme by two bridges of cations and ethylenediamine (EDA) is proposed to overcome the coffee-ring effect and electrochemical corrosion and experimentally achieve uniform, anticorrosive, and antiabrasive coatings on metallic surfaces. Anticorrosive capability reaches about 26 times higher than that without cation-controlled coatings at 12 h in extremely acidic, high-temperature, and high-humidity conditions and still enhances to 2.7 times over a week. Antiabrasive capability also reaches 2.5 times. Theoretical calculations show that the suspended materials are uniformly adsorbed on the surface mediated by complexed cations through strong cation–metal and cation−π interactions. Notably, the well-known conventional electrochemical corrosion induced by cations is avoided by EDA to control cations solubility in different coating processes. These findings provide a new efficient, cost-effective, facile, and scalable method to fabricate protective coatings on metallic materials and a methodology to study metallic nanostructures in solutions, benefitting practical applications including coatings, printing, dyeing, electrochemical protection, and biosensors.