From carbon dioxide to starch: no plants required Many plants turn glucose from photosynthesis into polymers that form insoluble starch granules ideal for long-term energy storage in roots and seeds. Cai et al . developed a hybrid system in which carbon dioxide is reduced to methanol by an inorganic catalyst and then converted by enzymes first to three and six carbon sugar units and then to polymeric starch. This artificial starch anabolic pathway relies on engineered recombinant enzymes from many different source organisms and can be tuned to produce amylose or amylopectin at excellent rates and efficiencies relative to other synthetic carbon fixation systems—and, depending on the metric used, even to field crops. —MAF

Solar overall water splitting is a promising sustainable approach for solar-to-chemical energy conversion, which harnesses solar irradiation to oxidize water to oxygen and reduce the protons to hydrogen. The water oxidation step is vital but difficult to achieve through inorganic photocatalysis. However, nature offers an efficient light-driven wateroxidizing enzyme, photosystem II (PSII). Here we report an overall water splitting naturalartificial hybrid system, in which the plant PSII and inorganic photocatalysts (for example, Ru/SrTiO 3 :Rh), coupled with an inorganic electron shuttle [Fe(CN) 6 3 À /Fe(CN) 6 4 À ], are integrated and dispersed in aqueous solutions. The activity of this hybrid photosystem reaches to around 2,489 mol H 2 (mol PSII) À 1 h À 1 under visible light irradiation, and solar overall water splitting is also achieved under solar irradiation outdoors. The optical imaging shows that the hybrid photosystems are constructed through the self-assembly of PSII adhered onto the inorganic photocatalyst surface. Our work may provide a prototype of natural-artificial hybrids for developing autonomous solar water splitting system.