The generation of hydrogen via alkaline electrolyzers is a promising approach to address the severe energy crisis. However, alkaline electrolyzers with alkaline electrolytes or pure water suffer from poor performance...

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The design of high‐performance and durable electrodes for the oxygen evolution reaction (OER) is crucial for pure‐water‐fed anion exchange membrane water electrolysis (AEMWE). In this study, an integrated electrode with vertically aligned ionomer‐incorporated nickel‐iron layered double hydroxide nanosheet arrays, used on one side of the liquid/gas diffusion layer, is fabricated for the OER. Transport highways in the fabricated integrated electrode, significantly improve the transport of liquid/gas, hydroxide ions, and electron in the anode, resulting in a high current density of 1900 mA cm–2 at 1.90 V in pure‐water‐fed AEMWE. Specifically, three‐electrode and single‐cell measurement results indicate that an anion‐exchange ionomer can increase the local OH– concentration on the integrated electrodes surface and facilitate the OER for pure‐water‐fed AEMWE. This study highlights a new approach to fabricating and understanding electrode architecture with enhanced performance and durability for pure‐water‐fed AEMWE.

To study the catalytic effects of (HO) (n = 1-3), the mechanisms of the reaction HO + HO →O + HO without and with (HO) (n = 1-3) have been investigated theoretically at the CCSD(T)/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ level of theory, coupled with rate constant calculations using the conventional transition state theory. Our results show that upon incorporation of (HO) (n = 1-3) into the channel of HO + O formation, two different reactions, i.e. HO + HO(HO) (n = 1-3) and HO + HO(HO) (n = 1-3), have been observed, and these two reactions are competitive with each other. The catalytic effects of (HO) (n = 1-3) mainly arise from the contribution of a single water vapor molecule; this is because the effective rate constants with water are respectively larger by 2-3 and 3-4 orders of magnitude than those of the reactions with (HO) and (HO). Furthermore, the catalytic effects of the water monomer mainly arise from the HOHO + HO reaction, and the enhancement factor of this reaction is obvious within the temperature range of 240.0-425.0 K, with the branching ratio (k'(RW)/k) of 17.27-80.77%. Overall, the present results provide a new example of how water and water clusters catalyze gas phase reactions under atmospheric conditions.

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The effect of a single water molecule on the HO2 + NO2 hydrogen abstraction reaction has been investigated by employing B3LYP and CCSD(T) theoretical approaches with the aug-cc-pVTZ basis set. The reaction without water has three types of reaction channels on both singlet and triplet potential energy surfaces, depending on how the HO2 radical approaches NO2. These correspond to the formation of trans-HONO + O2, cis-HONO + O2 and HNO2 + O2. Our calculated results show that triplet reaction channels are favorable and their total rate constant, at 298 K, is 2.01 × 10(-15) cm(3) molecule(-1) s(-1), which is in good agreement with experimental values. A single water molecule affects each one of these triplet reaction channels in the three different reactions of H2O···HO2 + NO2, HO2···H2O + NO2 and NO2···H2O + HO2, depending on the way the water interacts. Interestingly, the water molecule in these reactions not only acts as a catalyst giving the same products as the naked reaction, but also as a reactant giving the product of HONO2 + H2O2. The total rate constant of the H2O···HO2 + NO2 reaction is estimated to be slower than the naked reaction by 6 orders of magnitude at 298 K. However, the total rate constants of the HO2···H2O + NO2 and NO2···H2O + HO2 reactions are faster than the naked reaction by 4 and 3 orders of magnitude at 298 K, respectively. Their total effective rate constant is predicted to be 1.2 times that of the corresponding total rate constant without water at 298 K, which is in agreement with the prediction reported by Li et al. (science, 2014, 344, 292-296).

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Highly active, cost-effective, and stable electrocatalyst for oxygen evolution reaction (OER) is of primary importance in electrochemical water splitting. Although the direct growth of active components on the substrate is an effective strategy to enhance the catalytic activity, the weak adhesion between active material and substrate tremendously hampers their long-term utilization with excellent performance. Herein, a three-dimensional (3D) hollow structure of NiFe-layered double hydroxide (NiFe LDH) on NiFe foam (NiFe LDH@NiFe) is designed via acid-corrosion-induced strategy. The self-supported electrode was obtained through a process based on an autologous NiFe foam, in which the electrode/gas/electrolyte interface and electrocatalyst/substrate interface are delicately engineered. Remarkably, the NiFe LDH@NiFe only needs an ultralow overpotential of 201 mV to deliver a current density of 10 mA cm–2 for OER in 1 M KOH electrolyte, along with superb stability. The high catalytic activity is attributed to the intimate connection between the nanosheet arrays and substrate, superior intrinsic activity, and fast electron transfer. More importantly, the excellent hydrophilicity and aerophobicity of NiFe LDH@NiFe enables significantly improved infiltration of electrolytes, quick release of oxygen bubbles, and remarkably enhanced charge transfer. Thus, the obtained NiFe LDH@NiFe holds promise for electrocatalytic applications. Finally, the growth mechanism of NiFe LDH@NiFe is investigated and discussed in detail.