Developing efficient and low-cost electrocatalysts is critical for hydrogen evolution by water splitting. Nonsubjective reconstruction is one of the main issues that induces difficulty to develop and understand the well-defined structure during the electrocatalysis. By studying the anion-exchange between phosphate and hydroxide, cobalt hydroxide nanosheets incorporated with phosphate inherited from cobalt phosphate are obtained, which provides a new case of metallic transition metal hydroxide. Benefiting from more exposed active sites, effective electron transport, and optimized electronic structure, the residual phosphate in two-dimensional Co(OH) 2 gives rise to significant improvement in alkaline hydrogen evolution. Particularly, it can survive at 1600 mA cm −2 and maintain stability over 100 h under industrial conditions (6 M KOH at 60 °C). Density functional theory calculations and the confirmatory experiments of reverse anion-exchange from Co(OH) 2 are investigated to confirm the successful engineering of metallic character and electronic structure. This work provides a facile modification of practical electrodes with phosphate groups for industrial water electrolysis as well as gaining insights into the reconstruction of cobalt-based electrocatalysts in alkali to become an effective catalyst.

One of the key issues in the exploitation of natural gas hydrates is the geo-mechanical stability of hydrate-bearing sediments. Herein, based on classical molecular dynamics simulations, we have investigated the mechanical stability of CO2–N2 heteroclathrate hydrates (CNHHs) under uniaxial loading. The results show that the ratio of CO2 to N2 in the large and small water cages has a crucial effect on the mechanical properties and fracture behaviors of CNHHs. In most cases, CNHHs show brittle fracture behavior, and their ultimate tensile strength, failure strain, and Young’s modulus decrease significantly with the increase of CO2 ratio in small cages. However, when the small cages are all occupied by CO2, CNHHs display ductile fracture behavior. In particular, the CNHHs with a CO2 fraction of 0.75 have their hydrated cages broken by amorphization with increasing strain. The effect of CO2 molecules occupying the different types of water cages on fracture behavior has been discussed in detail. The results indicate that the occupancy of small cages by CO2 plays a decisive role in the fracture position. In the case of the nearest-neighbor large cages, the fracture positions are consistent with the positions of CO2 molecules with a high probability. The lattice distortion caused by the occupancy of the water cage by CO2 is the key factor affecting fracture behavior. These results should be helpful in understanding the deformation and fracture mechanisms of heteroclathrate hydrates as well as in assessing the impact of CH4–CO2/N2 replacement and CO2 sequestration on the geological stability of gas hydrate reservoirs.

By constructing Eu0.7Sr0.3MnO3 thin films/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (001) multiferroic heterostructures, the electrical transport properties of the Eu0.7Sr0.3MnO3 thin film under electro-photo dual control is studied. At room temperature, as the in-plane reading current increases from 1 μA to 100 μA, the polarization current effect gradually weakens, while the strain effect becomes more evident. As the temperature decreases from 300 K to 240 K, the ferroelectric field effect is observed to strengthen progressively. In addition, by applying light illumination, the ferroelectric field effect observed at 240 K can be suppressed, which proves that the light field can obviously control the tunable mechanism of electric field. Our results demonstrate that the temperature and light field play an important role in the switching between the electric field induced multiple tunable effects, such as polarization current effect, lattice strain effect and ferroelectric field effect. Meanwhile, the sensitivity of the Eu0.7Sr0.3MnO3 film to lattice strain enhances its application in tunable electronics.