Photocatalysis promises a solution to challenges associated with the intermittent nature of sunlight which is considered as renewable and ultimate energy source to power activities on Earth. This review aims to provide a broad overview of the field. Insight into natural photosynthesis is discussed first, which provides a scientific basis for most efforts on photocatalysis. Afterwards, the details of four existing types of photocatalysis are presented, namely photosynthesis by plants, photosynthesis by microalgae, photocatalysis by suspension and photoelectrocatalysis. Detailed analyses of simple photocatalysts and integrated photocatalytic systems are followed to shed light on the different functionalities of different components in a working photocatalyst. Special attention is given to the roles played by surface and interface chemical phenomena. Lastly, perspectives on artificial photosynthesis are discussed briefly at the end.

Two-dimensional materials are of current great interest for their promising applications to postsilicon microelectronics. Here we study, using first-principles calculations and a Monte Carlo simulation, the electronic structure and magnetism of CrI3 monolayer, whose bulk material is an interesting layered ferromagnetic (FM) semiconductor. Our results show that CrI3 monolayer remains FM with TC ∼ 75 K, and the FM order is due to a superexchange in the near-90 • Cr-I-Cr bonds. Moreover, we find that an itinerant magnetism could be introduced by carriers doping. Both electron doping and hole doping would render CrI3 monolayer half-metallic, and steadily enhance the FM stability. In particular, hole doping is three times as fast as electron doping in increasing TC, and a room temperature FM half-metallicity could be achieved in CrI3 monolayer via a half-hole doping. Therefore, CrI3 monolayer would be an appealing two-dimensional spintronic material.

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We successfully grew the high-quality single crystal of Rb0.78Fe2Se1.78, which shows sharp super-conducting transition in magnetic susceptibility and electrical resistivity. Resistivity measurements show the onset superconducting transition (Tc) at 32.1 K and zero resistivity at 30 K. From the low-temperature iso-magnetic-field magnetoresistance, large upper critical field Hc2(0) has been estimated as high as 180 T for in-plane field and 59 T for out-of-plane field. The anisotropy H ab c2 (0)/H c c2 (0) is around 3.0, right lying between those observed in KxFe2Se2 and CsxFe2Se2.