The alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) typically engage in chemical bonding as classical main-group elements through their s andp valence orbitals, where is the principal quantum number. Here we report the isolation and spectroscopic characterization of eight-coordinate carbonyl complexes M(CO) (where M = Ca, Sr, or Ba) in a low-temperature neon matrix. Analysis of the electronic structure of these cubic -symmetric complexes reveals that the metal-carbon monoxide (CO) bonds arise mainly from [M(d)] → (CO) π backdonation, which explains the strong observed red shift of the C-O stretching frequencies. The corresponding radical cation complexes were also prepared in gas phase and characterized by mass-selected infrared photodissociation spectroscopy, confirming adherence to the 18-electron rule more conventionally associated with transition metal chemistry.

No abstract

Solar-steam generation is one of the most promising technologies to mitigate the issue of clean water shortage using sustainable solar energy. Photothermal aerogels, especially the three-dimensional (3D) graphene-based aerogels, have shown unique merits for solar-steam generation, such as lightweight, high flexibility, and superior evaporation rate and energy efficiency. However, 3D aerogels require much more raw materials of graphene, which limits their large-scale applications. In this study, 3D photothermal aerogels composed of reduced graphene oxide (RGO) nanosheets, rice-straw-derived cellulose fibers, and sodium alginate (SA) are prepared for solar-steam generation. The use of rice straw fibers as skeletal support significantly reduces the need for the more expensive RGO by 43.5%, turning the rice straw biomass waste into value-added materials. The integration of rice straw fibers and RGO significantly enhances the flexibility and mechanical stability of the obtained photothermal RGO−SA−cellulose aerogel. The photothermal aerogel shows a strong broad-band light absorption of 96−97%. During solar-steam generation, the 3D photothermal aerogel effectively decreases the radiation and convection energy loss while enhancing energy harvesting from the environment, leading to an extremely high evaporation rate of 2.25 kg m −2 h −1 , corresponding to an energy conversion efficiency of 88.9% under 1.0 sun irradiation. The salinity of clean water collected during the evaporation of real seawater is only 0.37 ppm. The materials are environmentally friendly and cost-effective, showing great potential for real-world desalination applications.

Interfacial solar steam generation offers a promising and cost‐effective way for saline water desalination. However, salt accumulation and deposition on photothermal materials during saline and brine evaporation is detrimental to the stability and sustainability of solar evaporation. Although several antisalt strategies are developed, it is difficult to simultaneously achieve high evaporation rates (>2.0 kg m−2 h−1) and energy efficiencies. In this study, a self‐rotating photothermal evaporator with dual evaporation zones (i.e., high‐temperature and low‐temperature evaporation zones) is developed. This photothermal evaporator is sensitive to weight imbalance (<15 mg) thus is able to quickly respond to salt accumulation by rotation to refresh the evaporation surface, while the dual evaporation zones optimize the energy nexus during solar evaporation, simultaneously realizing excellent salt‐resistant performance and high evaporation rate (2.6 kg m−2 h−1), which can significantly contribute to the real‐world application of solar steam generation technology.