Acidic oxygen evolution electrocatalysts based on earth abundant elements are essential for the widespread application of proton-exchange membrane water electrolyzers. Spinel oxides containing cobalt and manganese are promising candidates. Here, the oxygen evolution activity and stability of surfactant-free cobalt and manganese spinel oxides with an average side length of 7 nm are evaluated in 0.1 M HClO₄. The oxygen evolution activity follows the trend Co₃O₄/CP > Co_1.27Mn_1.27Fe_0.46O₄/CP > Co₂MnO₄/CP > Mn₃O₄/CP, and only Co₃O₄/CP is stable towards the long-term OER in acid. The origin for increased activity of Co₃O₄/CP is also investigated, and the results indicate that the Co site is intrinsically more active towards the OER than the Mn site. The lower charge transfer resistance, lower apparent activation energy and close to optimum hydroxyl group adsorption energy corroborate the higher intrinsic OER activity of Co₃O₄/CP. For Co_1.27Mn_1.27Fe_0.46O₄ and Co₂MnO₄, electron interaction that alters the acidity of the metal center exists. The OER mechanism involves a decoupled proton–electron transfer process, as indicated by the non-zero reaction order of [H⁺] in the reversible hydrogen scale. Severe leaching of metal-containing species is detected during the long-term oxygen evolution reaction in acid.

Flexible electrothermal heaters have attracted abundant attention in recent years due to their wide applications, but their preparation with high efficiency remains a challenge. Here in this work, a highly stable and bending-tolerant flexible heater was fabricated with graphite nanosheets and cellulose fibers through a scalable papermaking procedure. Its electrothermal property can be enhanced by a hot-pressing treatment and introduction of cationic polyacrylamide (CPAM) during the papermaking protocol. The flexible heater may quickly reach its maximum temperature of 239.8 °C in around 1 min at a voltage of 9 V. The power density was up to 375.3 °C cm² w⁻¹. It appeared to have a high tolerance for bending deformation with various curvatures, and the temperature remained stable even under 100 bending with frequency of around 0.17 Hz. Over 100 alternatively heating and cooling cycles, it worked stably as well. It was proved to be used as wearable heating equipment, soft heaters, and aircraft deicing devices, suggesting its great prospect in the field of heat management.

Gas drilling technology is an effective method to protect low permeability tight sandstone reservoirs from damage. However, using this technology to drill high-pressure fractured reservoirs, the fluid flow characteristics are extremely complex, leading to drilling safety challenges. Therefore, based on the conservation equations of mass, momentum, and energy, a new transient coupled flow model in matrix-fracture is established for high-pressure gas reservoirs opened by gas drilling, considering convection term and energy equation, to research the pressure and flow velocity transient behaviors. This model is solved by Shaher Momani’s algorithm and CyabJiBe format, and the type curves of the pressure and flow velocity are plotted. The three flow stages are developed, and the impact of parameters and equation terms on the transient flow behavior is analyzed and discussed, such as the energy equation, the matrix permeability (), the fracture aperture (), and the fracture outlet pressure. It is found that the energy equation term of the model has a great influence on the transient characteristics such as velocity and pressure, which cannot be ignored. In the first flow stage, the flow velocity characteristics are not affected by the matrix parameters being extremely unstable, but in the second and third stages, the influence of the gas supplied to fracture cannot be ignored. The proposed transient coupled flow model provides a new understanding of the transient flow behavior in matrix-fracture for high-pressure reservoirs during gas drilling, which can be used to interpret the characteristics of pressure and velocity more realistically, to provide support for safe drilling of gas drilling.