Low‐temperature electricity‐driven water splitting is an established technology for hydrogen production. However, the two main types, namely proton exchange membrane (PEM) and liquid alkaline electrolysis, have limitations. For instance, PEM electrolysis requires a high amount of costly platinum‐group‐metal (PGM) catalysts, and liquid alkaline electrolysis is not well suited for intermittent operation. Herein we report a highly efficient alkaline polymer electrolysis design, which uses a membrane‐electrode assembly (MEA) based on low‐cost transition‐metal catalysts and an anion exchange membrane (AEM). This system exhibited similar performance to the one achievable with PGM catalysts. Moreover, it is very suitable for intermittent power operation, durable, and able to efficiently operate at differential pressure up to 3 MPa. This system combines the benefits of PEM and liquid alkaline technologies allowing the scalable production of low‐cost hydrogen from renewable sources. 相似文献
For anion exchange membranes (AEMs), achieving efficient hydroxide conductivity without excessive hydrophilicity presents a challenge. Hence, new strategies for constructing mechanically strengthened and hydroxide conductive (especially at controlled humidity) membranes are critical for developing better AEMs. Macromolecular modification involving ylide chemistry (Wittig reaction) for the fabrication of novel AEMs with an interpenetrating polymer network structure is reported. The macromolecular modification is cost effective, facile, and based on a one‐pot synthesis. AEM water uptake is reduced to 3.6 wt% and a high hydroxide conductivity (69.7 mS cm−1, 90 °C) is achieved simultaneously. More importantly, the membrane exhibits similar tensile strength (>35 MPa) and comparable flexibility in both dry and wet states. These AEMs could find further applications within anion exchange membrane fuel cells with low humidity or photoelectric assemblies.
Exploring materials with regulated local structures and understanding how the atomic motifs govern the reactivity and durability of catalysts are a critical challenge for designing advanced catalysts. Herein we report the tuning of the local atomic structure of nickel–iron layered double hydroxides (NiFe‐LDHs) by partially substituting Ni2+ with Fe2+ to introduce Fe‐O‐Fe moieties. These Fe2+‐containing NiFe‐LDHs exhibit enhanced oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at the current density of 10 mA cm?2, which is among the best OER catalytic performance to date. In‐situ X‐ray absorption, Raman, and electrochemical analysis jointly reveal that the Fe‐O‐Fe motifs could stabilize high‐valent metal sites at low overpotentials, thereby enhancing the OER activity. These results reveal the importance of tuning the local atomic structure for designing high efficiency electrocatalysts. 相似文献
Anion exchange membranes (AEMs) are core components in anion exchange membrane water electrolyzers (AEM-WEs). However, the stability of functional quaternary ammonium cations, especially under high temperatures and harsh alkaline conditions, seriously affects their performance and durability. Herein, we synthesized a 1-methyl-3,3-diphenylquinuclidinium molecular building unit. Density functional theory (DFT) calculations and accelerated aging analysis indicated that the quinine ring structure was exceedingly stable, and the SN2 degradation mechanism dominated. Through acid-catalyzed Friedel–Crafts polymerization, a series of branched poly(aryl-quinuclidinium) (PAQ-x) AEMs with controllable molecular weight and adjustable ion exchange capacity (IEC) were prepared. The stable quinine structure in PAQ-x was verified and retained in the ex situ alkaline stability. Furthermore, the branched polymer structure reduces the swelling rate and water uptake to achieve a tradeoff between dimensional stability and ionic conductivity, significantly improving the membrane's overall performance. Importantly, PAQ-5 was used in non-noble metal-based AEM-WE, achieving a high current density of 8 A cm−2 at 2 V and excellent stability over 2446 h in a gradient constant current test. Based on the excellent alkaline stability of this diaryl-quinuclidinium group, it can be further considered as a multifunctional building unit to create multi-topological polymers for energy conversion devices used in alkaline environments. 相似文献
Electrochemically active hollow nanostructured materials hold great promise in diverse energy conversion and storage applications, however, intricate synthesis steps and poor control over compositions and morphologies have limited the realization of delicate hollow structures with advanced functional properties. In this study, we demonstrate a one‐step wet‐chemical strategy for co‐engineering the hollow nanostructure and anion intercalation of nickel cobalt layered double hydroxide (NiCo‐LDH) to attain highly electrochemical active energy conversion and storage functionalities. Self‐templated pseudomorphic transformation of cobalt acetate hydroxide solid nanoprisms using nickel nitrate leads to the construction of well‐defined NiCo‐LDH hollow nanoprisms (HNPs) with multi‐anion intercalation. The unique hierarchical nanosheet‐assembled hollow structure and efficiently expanded interlayer spacing offer an increased surface area and exposure of active sites, reduced mass and charge transfer resistance, and enhanced stability of the materials. This leads to a significant improvement in the pseudocapacitive and electrocatalytic properties of NiCo‐LDH HNP with respect to specific capacitance, rate and cycling performance, and OER overpotential, outperforming most of the recently reported NiCo‐based materials. This work establishes the potential of manipulating sacrificial template transformation for the design and fabrication of novel classes of functional materials with well‐defined nanostructures for electrochemical applications and beyond. 相似文献
下载免费PDF全文