In-plane anisotropic layered materials such as black phosphorus (BP) have emerged as an important class of two-dimensional (2D) materials that bring a new dimension to the properties of 2D materials, hence providing a wide range of opportunities for developing conceptually new device applications. However, all of recently reported anisotropic 2D materials are relatively narrow-bandgap semiconductors (<2 eV), and there has been no report about this type of materials with wide bandgap, restricting the relevant applications such as polarization-sensitive photodetection in short wave region. Here we present a new member of the family, germanium diselenide (GeSe) with a wide bandgap of 2.74 eV, and systematically investigate the in-plane anisotropic structural, vibrational, electrical, and optical properties from theory to experiment. Photodetectors based on GeSe exhibit a highly polarization-sensitive photoresponse in short wave region due to the optical absorption anisotropy induced by in-plane anisotropy in crystal structure. Furthermore, exfoliated GeSe flakes show an outstanding stability in ambient air which originates from the high activation energy of oxygen chemisorption on GeSe (2.12 eV) through our theoretical calculations, about three times higher than that of BP (0.71 eV). Such unique in-plane anisotropy and wide bandgap, together with high air stability, make GeSe a promising candidate for future 2D optoelectronic applications in short wave region.

Defect passivation using oxygen has been identified as an efficient and convenient approach to suppress nonradiative recombination and improve the photovoltaic performance of hybrid organic–inorganic halide perovskites (HHPs). However, oxygen can seriously undermine the chemical stability of HHPs due to the reaction of superoxide with protonated organic cations such as CH3NH3 + and [(NH2)2CH]+, thus hindering the deep understanding of how oxygen affects their defect properties. Here we substitute free-proton inorganic Cs+ for organic moiety to avoid the negative effect of oxygen and then systematically investigate the oxygen passivation mechanism in all-inorganic halide perovskites (IHPs) from theory to experiment. We find that, in contrast to conventional oxygen molecule passivation just through physisorption on the surface of perovskites, the oxygen atom can provide a better passivation effect due to its stronger interaction with perovskites. The key point to achieve O-passivated perovskites rather than O2 is the dry-air processing condition, which can dissociate the O2 into O during the annealing process. O-passivated IHP solar cells exhibit enhanced power conversion efficiency (PCE) and better air stability than O2-passivated cells. These results not only provide deep insights into the passivation effect of oxygen on perovskites but also demonstrate the great potential of IHPs for high photovoltaic performance with simplified ambient processing.

A Co-doped NiO/NiFe2O4 mesoporous nanosheet array on Ni foam is constructed for highly efficient overall water splitting.

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4) is an effective target for green herbicide discovery. In this work, we reported the unexpected discovery of a novel series of N-phenylaminomethylthioacetylpyrimidine-2,4-diones (2−6) as promising PPO inhibitors based on investigating the reaction intermediates of our initially designed N-phenyluracil thiazolidinone ( 1). An efficient one-pot procedure that gave 41 target compounds in good to high yields was developed. Systematic Nicotiana tabacum PPO (NtPPO) inhibitory and herbicidal activity evaluations led to identifying some compounds with improved NtPPO inhibition potency than saflufenacil and good post-emergence herbicidal activity at 37.5−150 g of ai/ha. Among these analogues, ethyl 2-((((2chloro-4-fluoro-5-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-3,6-dihydropyrimidin-1(2H)-yl)phenyl)amino)methyl)thio)acetate (2c) (K i = 11 nM), exhibited excellent weed control at 37.5−150 g of ai/ha and was safe for rice at 150 g of ai/ha, indicating that compound 2c has the potential to be developed as a new herbicide for weed management in paddy fields. Additionally, our molecular simulation and metabolism studies showed that the side chains of compound 2c could form a hydrogen-bond-mediated seven-membered ring system; substituting a methyl group at R 1 could reinforce the hydrogen bond of the ring system and reduce the metabolic rate of target compounds in planta.