The alkaline stability of N‐heterocyclic ammonium (NHA) groups is a critical topic in anion‐exchange membranes (AEMs) and AEM fuel cells (AEMFCs). Here, we report a systematic study on the alkaline stability of 24 representative NHA groups at different hydration numbers (λ) at 80 °C. The results elucidate that γ‐substituted NHAs containing electron‐donating groups display superior alkaline stability, while electron‐withdrawing substituents are detrimental to durable NHAs. Density‐functional‐theory calculations and experimental results suggest that nucleophilic substitution is the dominant degradation pathway in NHAs, while Hofmann elimination is the primary degradation pathway for NHA‐based AEMs. Different degradation pathways determine the alkaline stability of NHAs or NHA‐based AEMs. AEMFC durability (from 1 A cm−2 to 3 A cm−2) suggests that NHA‐based AEMs are mainly subjected to Hofmann elimination under 1 A cm−2 current density for 1000 h, providing insights into the relationship between current density, λ value, and durability of NHA‐based AEMs.

The impact of a tapioca-based artificial diet on the developmental rate, life history parameters, and fertility was examined over five consecutive generations for the cotton bollworm, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae), a highly polyphagous pest of many agricultural crops. The study showed that when fed the tapioca-based artificial diet during larval stage, larval and pupal developmental period, percent pupating, pupal weight, emergence rate of male and female, longevity, fecundity and hatching were non-significantly different than that of the control agar-based artificial diet. Moreover, the cost to rear on tapioca-based diet approached 2.13 times less than the cost of rearing on the agar-based artificial diet. These results demonstrate the effectiveness and potential cost savings of the tapioca-based artificial diet for rearing H. armigera.

Exploring low-cost, efficient, and stable nonprecious alternatives for Pt-based catalysts is of significance in the hydrogen evolution reaction (HER) in acidic environments. Previous experiments have found that 3d transition metals Fe, Co, and Ni incorporated with inert carbon templates or carbon–nitrogen materials exhibit long-term durability and high HER activity in acidic electrolytes. To clarify the underlying mechanism determining the HER activity, here we report a theoretical investigation of the HER on a series of defective carbon nanotubes (CNTs), doped with atomic Co (CoCNT­(n,n), n = 3, 5, 7, and 9) and codoped with Co and double N (CoN2CNT­(5,5)), based on the first-principle density functional calculations. Our calculations indicate that the HER on these Co- and Co, N-(co)­doped CNTs occurs via the Volmer–Heyrovsky mechanism, and the primary active sites are the C atoms adjacent to the metal center. The enhancement of the HER activity is due to uplifting of the p-band center (εp) of the active C atoms induced by using a CNT with appropriate curvature, Co doping, and Co and N codoping. The HER activity of CoCNT­(n,n)­s follows a volcano dependence with surface curvature, showing nearly six orders of magnitude difference in exchange currents, peaked at CoCNT­(5,5), with the activity comparable with Pt-catalysts. Doped with double N atoms in CoCNT­(5,5), the exchange current could be further substantially enhanced (by 30 times), even one order of magnitude higher than that of Pt(111). The fact that CoN2CNT­(5,5) has an εp (−4.16 eV) very close to the optimum value for the maximum exchange current (−4.14 eV) justifies the advance in improving the HER activity of CNTs.

The metal−vacuum models used to analyze the thermodynamics of the oxygen reduction reaction (ORR) completely overlook the role of electrolytes in the electrochemical process and thus cannot reflect the actual kinetic process occurring at the metal−electrolyte interface. Therefore, based on the real experimental process, the current work elucidates the chemical interactions between the electrolyte and the chemical species for the ORR via a novel metal−electrolyte model for the first time by effectively elucidating the correlation between ORR kinetics and polarization curves. Our simulation model analysis comprises the study of all possible ORR mechanisms on different Pt surfaces (Pt(111), Pt(110), and Pt(100)) and PtNi alloys with different compositions (Pt 3 Ni(111), Pt 2 Ni 2 (111), and PtNi 3 ( 111)). The obtained results demonstrate that the hydrogenation of adsorbed oxygen to form adsorbed hydroxyl (R8), whose immense control weight is reflected by a coverage of adsorbed oxygen (θ O* ) of about 1, is the rate-determining step (RDS) in the four-electron-dominated ORR process. A direct correlation has been established by the great fitting of polarization curves from theoretical ORR kinetics obtained via both the metal−electrolyte model and experimental measurement. This study reveals that among the different Pt surfaces and PtNi alloys, Pt 3 Ni(111) exhibits the highest ORR activity with the lowest free energy barrier of E a (0.74 eV), the smallest value of |ΔG O* − 2.46| (0.80 eV), the highest reaction rate r (9.98 × 10 5 s −1 per site), and a more positive half-wave potential U 1/2 (0.93 V). In contrast to previous model studies, this work provides a more accurate theoretical system for catalyst screening, which will help researchers to better understand the experimental phenomena and will be a guiding piece of work for catalyst design and development.