Here, a hierarchical nanostructure composed of Ni-doped α-FeOOH (Ni:FeOOH) nanosheets coupled with N-doped graphite foam (NGF) is demonstrated as a three-dimensional (3D) self-supported electrocatalyst for highly efficient and durable water oxidation. A facile, one-step directional growth of catalytically active Ni:FeOOH nanosheets on highly conducting 3D NGF results in a fully integrated, hierarchical, nanostructured electrocatalyst with (i) the high intrinsic activity of Ni:FeOOH, (ii) the outstanding electrical conductivity of NGF, and (iii) a well-defined porous structure with an enhanced active surface area. As a result, the self-supported 3D Ni:FeOOH/NGF electrocatalyst exhibits remarkable electrocatalytic activity for the oxygen evolution reaction (OER) in an alkaline solution with an overpotential of 214 mV at 10 mA/cm2, a high stability for over 60 h, a low Tafel slope of 36.2 mV dec–1, and a capability of delivering a high current density of 300 mA/cm2 at an overpotential of 368 mV. In contrast to photodeposition, electrodeposition, and hydrothermal methods for the formation/integration of (oxy)­hydroxides, this facile solution strategy for designing an attractive and efficient structure with a highly active metal (oxy)­hydroxide and highly conducting NGF provides a pathway to develop other earth-abundant electrocatalysts for a multitude of energy-conversion-device applications.

Development of assisted reproductive technologies is necessary to obtain fertilized oocytes in a subfertile transgenic mouse strain. Here, we showed the application of laser-assisted drilling of the zona pellucida to in vitro fertilization of cryopreserved mouse oocytes with sperm from subfertile transgenic mice (C57BL/6N-Tg(UCP/FAD2)U8 strain). After cryopreservation by vitrification, the recovery and survival rates of the zona-drilled mouse oocytes were 97% (97/100) and 94% (91/97), respectively. In vitro fertilization of the cryopreserved zona-drilled mouse oocytes with sperm from the subfertile transgenic mice was greatly facilitated (60%, 55/91) compared to that of the cryopreserved zona-intact mouse oocytes (11%, 81/768). In vitro fertilized embryos that developed to the 2-cell stage were again cryopreserved by vitrification, and after warming they were transferred into recipient females. Subsequently, six viable offspring were delivered, and all were confirmed to be transgenic mice. These results indicate that laser-assisted zona drilling of oocytes combined with cryopreservation by vitrification may be a useful approach for large-scale production of in vitro fertilized embryos for managing transgenic mouse strains with reproductive disabilities such as subfertile sperm.

Transition-metal phosphide (TMP) nanostructures have been extensively studied for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, phase-controlled synthesis of colloidal Ni2P nanocrystals (NCs) or related heterostructures remains challenging and their use as bifunctional electrocatalysts in overall water splitting (OWS) is not systematically studied. Herein, zero-dimensional (0D) colloidal Ni2P NCs are synthesized using a robust solution-phase method and encapsulated in two-dimensional (2D) N- and S-doped graphene (NSG) nanosheets via facile ex situ sonication to form a 0D@2D Ni2P@NSG heterostructure. The interaction between surface functionalities of Ni2P NCs and defective NSG via strong van der Waals force provides a robust sheath to Ni2P NCs when encapsulated in NSG nanosheets, further enhancing the specific surface area and active site exposure. Density functional theory calculations indicate that the dual interaction of N and S dopants with Ni2P benefits the synergistic effect of optimized water and hydrogen free energy adsorption. As a result, Ni2P@NSG electrocatalysts manifest high catalytic activity toward HER and OER, and a two-electrode alkaline electrolyzer assembled by Ni2P@NSG as both an anode and a cathode requires only 1.572 V to reach a current density of 10 mA/cm2.

A simple and eco-friendly method of solution processing of Cu2SnS3 (CTS) absorbers using an aqueous precursor solution is presented. The precursor solution was prepared by mixing metal salts into a mixture of water and ethanol (5:1) with monoethanolamine as an additive at room temperature. Nearly carbon-free CTS films were formed by multispin coating the precursor solution and heat treating in air followed by rapid thermal annealing in S vapor atmosphere at various temperatures. Exploring the role of the annealing temperature in the phase, composition, and morphological evolution is essential for obtaining highly efficient CTS-based thin film solar cells (TFSCs). Investigations of CTS absorber layers annealed at various temperatures revealed that the annealing temperature plays an important role in further improving device properties and efficiency. A substantial improvement in device efficiency occurred only at the critical annealing temperature, which produces a compact and void-free microstructure with large grains and high crystallinity as a pure-phase absorber layer. Finally, at an annealing temperature of 600 °C, the CTS thin film exhibited structural, compositional, and microstructural isotropy by yielding a reproducible power conversion efficiency of 1.80%. Interestingly, CTS TFSCs exhibited good stability when stored in an air atmosphere without encapsulation at room temperature for 3 months, whereas the performance degraded slightly when subjected to accelerated aging at 80 °C for 100 h under normal laboratory conditions.

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