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The nonlinear dependence of the mean-squared displacement (MSD) on time is a common characteristic of particle transport in complex environments. Frequently, this anomalous behavior only occurs transiently before the particle reaches a terminal Fickian diffusion. This study shows that a system of hierarchically coupled Ornstein–Uhlenbeck equations is able to describe both transient subdiffusion and transient superdiffusion dynamics, as well as their sequential combinations. To validate the model, five distinct experimental, molecular dynamics simulation, and theoretical studies are successfully described by the model. The comparison includes the transport of particles in random optical fields, supercooled liquids, bedrock, soft colloidal suspensions, and phonons in solids. The model’s broad applicability makes it a convenient tool for interpreting the MSD profiles of particles exhibiting transient anomalous diffusion. 

Abstract CO₂electroreduction (CO₂R) operating in acidic media circumvents the problems of carbonate formation and CO₂crossover in neutral/alkaline electrolyzers. Alkali cations have been universally recognized as indispensable components for acidic CO₂R, while they cause the inevitable issue of salt precipitation. It is therefore desirable to realize alkali‐cation‐free CO₂R in pure acid. However, without alkali cations, stabilizing *CO₂intermediates by catalyst itself at the acidic interface poses as a challenge. Herein, we first demonstrate that a carbon nanotube‐supported molecularly dispersed cobalt phthalocyanine (CoPc@CNT) catalyst provides the Co single‐atom active site with energetically localizeddstates to strengthen the adsorbate‐surface interactions, which stabilizes *CO₂intermediates at the acidic interface (pH=1). As a result, we realize CO₂conversion to CO in pure acid with a faradaic efficiency of 60 % at pH=2 in flow cell. Furthermore, CO₂is successfully converted in cation exchanged membrane‐based electrode assembly with a faradaic efficiency of 73 %. For CoPc@CNT, acidic conditions also promote the intrinsic activity of CO₂R compared to alkaline conditions, since the potential‐limiting step, *CO₂to *COOH, is pH‐dependent. This work provides a new understanding for the stabilization of reaction intermediates and facilitates the designs of catalysts and devices for acidic CO₂R. 

Electrochemical reduction of nitric oxide (NOER) is a promising technology for the removal of harmful N-containing species in groundwater under mild conditions. In this work, by means of density functional theory computations, we systematically investigated the potential of utilizing experimentally feasible transition metal–N 4 /graphenes as NOER catalysts. Our results revealed that NO molecules can be moderately activated on a Co–N 4 moiety embedded into graphene, and the subsequent NOER steps can proceed to form either NH 3 at low coverages or N 2 O at higher coverages. Especially, the computed onset potential of NOER on Co–N 4 /graphene ( ca. −0.12 V) is comparable to (or even better than) those on well-established Pt-based catalysts. Thus, Co–N 4 /graphene is a promising single-atom-catalyst with high efficiency for NO electrochemical reduction, which opens a new avenue for NO reduction for environmental remediation.