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Solar steam generation is an efficient way to address global freshwater shortages. However, water evaporation suffers from either inefficient heat conduction or relies on expensive materials and complex equipment. Herein, a porous hydrogel (AC‐H) with molecular meshes, micron channels, and internal gaps is fabricated and used for metal ion adsorption. AC‐H exhibits excellent uptake ability and can attain the levels required by industrial water safety standards. Subsequently, the exhausted AC‐H hydrogel is vulcanized in situ (AC‐MS) and upcycled for solar steam generation resulting in ≈1.41 kg m−2 h−1 evaporation rate under one sun irradition, which reduces costs and converts the waste into a resource. Furthermore, a heat management strategy is developed where a cold surface of specific area is introduced between the AC‐MSx and bulk water to adsorb the heat loss. When the cold area is increased, the energy in the bulk water can be extracted by the coldsurface. which enhances the water evaporation rate. Significantly, the theoretical simulations are in good agreement with the experimental results. Therefore, this research provides a novel strategy to upcycle exhausted materials for photothermal technologies and reduces the heat conduction during solar‐to‐thermal evaporation. [ABSTRACT FROM AUTHOR]

To estimate the reaction free energies of the hydrogen evolution reaction (HER) on under-coordinated metallic sites, density function theory (DFT) calculations are usually employed to calculate the hydrogen adsorption energy with an "only-one-hydrogen-adsorption" model, assuming that adsorption with one hydrogen is the most thermodynamically favorable situation during catalysis. In this brief report, we show that on many single atom sites, adsorption of more than one hydrogen is sometimes even more thermodynamically favorable, with the presence of two or three hydrogens resulting in lower adsorption energies. These interesting non-monotonic trends indicate that modeling HER and other hydrogen-related reactions on under-coordinated sites should also consider the numbers of hydrogen being adsorbed at the same site, otherwise the results could deviate from real experimental situations. [ABSTRACT FROM AUTHOR]