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Abstract The ionic transport process is an important counterpart to charge transport in oil‐paper insulation, and it significantly impacts oil flow electrification at the oil‐paper interface. Despite this, the dynamics of this phenomenon and the underlying mechanisms remain unclear, particularly at the molecular level. To understand this fundamental aspect, we conduct Molecular Dynamics study on the transport behaviour of an impurity ion in different oil‐paper insulation models under various external electric fields. Different influence factors, such as external electric fields, temperatures, and local structural characteristics, are investigated in relation to the corresponding ionic mobility in different polymer models. According to the simulations, ionic mobility and its response to electric fields are higher in weaker electrostatic models. As a result, mineral oil exhibits the highest ionic mobility and the most substantial enhancement of ionic mobility by external electric fields, followed by vegetable oil, oil‐paper blends, and insulating paper. This significant deviation in ionic mobility between oil and paper leads to the formation of an electric double layer near the oil‐paper interface. The underlying physical mechanisms of different ionic mobility and its response to the electric field in different polymer models could be explained by the different polymer structural influences in terms of interaction energy and coordination numbers in a static manner, as well as by the interactions between the impurity ion and its surrounding atoms in terms of lifetime correlation functions and velocity autocorrelation functions in a dynamic manner. In addition, the influence of temperature on ionic mobility in mineral and vegetable oil is examined, and their activation energies are calculated. Advancing in the fundamental understanding of the dynamics of the ion transport process in oil‐paper insulation is vital to improving their insulating properties for oil‐impregnated power transformers.

Abstract Electrochemical water splitting offers a most promising pathway for “green hydrogen” generation. Even so, it remains a struggle to improve the electrocatalytic performance of non‐noble metal catalysts, especially bifunctional electrocatalysts. Herein, aiming to accelerate the hydrogen and oxygen evolution reactions, an oxygen‐bridged cobalt–chromium (Co‐O‐Cr) dual‐sites catalyst anchored on cobalt phosphide synthesized through MOF‐mediation are proposed. By utilizing the filling characteristics of 3d orbitals and modulated local electronic structure of the catalytic active site, the well‐designed catalyst requires only an external voltage of 1.53 V to deliver the current density of 20 mA cm−2 during the process of water splitting apart from the superb HER and OER activity with a low overpotential of 87 and 203 mV at a current density of 10 mA cm−2, respectively. Moreover, density functional theory (DFT) calculations are utilized to unravel mechanistic investigations, including the accelerated adsorption and dissociation process of H2O on the Co‐O‐Cr moiety surface, the down‐shifted d‐band center, a lowered energy barrier for the OER and so on. This work offers a design direction for optimizing catalytic activity toward energy conversion.