Small and salty CO ₂ reduction scheme: Most artificial photosynthesis approaches focus on making hydrogen. Modifying CO ₂ , as plants and microbes do, is more chemically complex. Asadi et al. report that fashioning WSe ₂ and related electrochemical catalysts into nanometer-scale flakes greatly improves their activity for the reduction of CO ₂ to CO. An ionic liquid reaction medium further enhances efficiency. An artificial leaf with WSe ₂ reduced CO ₂ on one side while a cobalt catalyst oxidized water on the other side. Science , this issue p. 467

Batteries based on sodium superoxide and on potassium superoxide have recently been reported^1,2,3. However, there have been no reports of a battery based on lithium superoxide (LiO₂), despite much research^4,5,6,7,8 into the lithium–oxygen (Li–O₂) battery because of its potential high energy density. Several studies^{9,10,11,12,13,14,15,16} of Li–O₂ batteries have found evidence of LiO₂ being formed as one component of the discharge product along with lithium peroxide (Li₂O₂). In addition, theoretical calculations have indicated that some forms of LiO₂ may have a long lifetime¹⁷. These studies also suggest that it might be possible to form LiO₂ alone for use in a battery. However, solid LiO₂ has been difficult to synthesize in pure form¹⁸ because it is thermodynamically unstable with respect to disproportionation, giving Li₂O₂ (refs 19, 20). Here we show that crystalline LiO₂ can be stabilized in a Li–O₂ battery by using a suitable graphene-based cathode. Various characterization techniques reveal no evidence for the presence of Li₂O₂. A novel templating growth mechanism involving the use of iridium nanoparticles on the cathode surface may be responsible for the growth of crystalline LiO₂. Our results demonstrate that the LiO₂ formed in the Li–O₂ battery is stable enough for the battery to be repeatedly charged and discharged with a very low charge potential (about 3.2 volts). We anticipate that this discovery will lead to methods of synthesizing and stabilizing LiO₂, which could open the way to high-energy-density batteries based on LiO₂ as well as to other possible uses of this compound, such as oxygen storage.

Global warming due to the high concentration of anthropogenic CO₂ in the atmosphere is considered one of the world's leading challenges in the 21^st century as it leads to severe consequences such as climate change, extreme weather events, ocean warming, sea-level rise, declining Arctic sea ice, and the acidification of oceans. This encouraged advancing technologies that sequester carbon dioxide from the atmosphere or capture those emitted before entering the carbon cycle. Recently, CO₂ capture, utilizing porous materials was established as a very favorable route, which has drawn extreme interest from scientists and engineers due to their advantages over the absorption approach. In this review, we summarize developments in porous adsorbents for CO₂ capture with emphasis on recent studies. Highly efficient porous adsorption materials including metal–organic frameworks (MOFs), zeolites, mesoporous silica, clay, porous carbons, porous organic polymers (POP), and metal oxides (MO) are discussed. Besides, advanced strategies employed to increase the performance of CO₂ adsorption capacity to overcome their drawbacks have been discoursed.