Ammonia, as a significant chemical for fertilizer production and also a promising energy carrier, is mainly produced through the traditional energy-intensive Haber–Bosch process. Recently, the electrocatalytic N2 reduction reaction (NRR) for ammonia synthesis has received tremendous attention with the merits of energy saving and environmental friendliness. To date, the development of the NRR process is primarily hindered by the competing hydrogen evolution reaction (HER), whereas the corresponding strategies for inhibiting this undesired side reaction to achieve high NRR selectivity are still quite limited. Furthermore, for such a complex reaction involving three gas–liquid–solid phases and proton/electron transfer, it is also rather meaningful to decouple and summarize the current strategies for suppressing H2 evolution in terms of NRR mechanisms, kinetics, thermodynamics, and electrocatalyst design in detail. Herein, on the basis of the NRR mechanisms, we systematically summarize the recent strategies to inhibit the HER for a highly selective electrocatalytic NRR, focusing on limiting the proton- and electron-transfer kinetics, shifting the chemical equilibrium, and designing the electrocatalysts. Additionally, insights into boosting the NRR selectivity and efficiency for practical applications are also presented in detail with regard to the determination of ammonia, the activation of the N2 molecule, the regulation of the gas–liquid–solid three-phase interface, the coupled NRR with value-added oxidation reactions, and the development of flow cell reactors.

Strategies to suppress hydrogen evolution for highly selective electrocatalytic nitrogen reduction: challenges and perspectives

Electrochemical water splitting has attracted significant attention as a key pathway for the development of renewable energy systems. Fabricating efficient electrocatalysts for these processes is intensely desired to reduce their overpotentials and facilitate practical applications. Recently, metal-organic framework (MOF) nanoarchitectures featuring ultrahigh surface areas, tunable nanostructures, and excellent porosities have emerged as promising materials for the development of highly active catalysts for electrochemical water splitting. Herein, the most pivotal advances in recent research on engineering MOF nanoarchitectures for efficient electrochemical water splitting are presented. First, the design of catalytic centers for MOF-based/derived electrocatalysts is summarized and compared from the aspects of chemical composition optimization and structural functionalization at the atomic and molecular levels. Subsequently, the fast-growing breakthroughs in catalytic activities, identification of highly active sites, and fundamental mechanisms are thoroughly discussed. Finally, a comprehensive commentary on the current primary challenges and future perspectives in water splitting and its commercialization for hydrogen production is provided. Hereby, new insights into the synthetic principles and electrocatalysis for designing MOF nanoarchitectures for the practical utilization of water splitting are offered, thus further promoting their future prosperity for a wide range of applications.

Designing MOF Nanoarchitectures for Electrochemical Water Splitting.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/sus2.3

Recent advances in vacancy engineering of metal-organic frameworks and their derivatives for electrocatalysis

Electrocatalysis has been the cornerstone for enhancing energy efficiency, minimizing environmental impacts and carbon emissions, and enabling a more sustainable way of meeting global energy needs....

Operando Methods in Electrocatalysis

https://scholars.cityu.edu.hk/files/78455697/74467077.pdf.pdf

Advances in metal–organic frameworks and their derivatives for diverse electrocatalytic applications

Industrially, NH3 synthesis is largely dependent on the Haber–Bosch method which consumes a lot of energy and emits huge amounts of CO2. Recently, the electrochemical N2 reduction reaction (NRR) has been recognized as a promising method to achieve clean and sustainable NH3 production, thus highly efficient and durable catalysts are urgently desired. In this paper, we report a MOF-derived carbon/Y-stabilized ZrO2 nanocomposite (C@YSZ) that works as an efficient electrocatalyst for NRR in 0.1 M Na2SO4. It achieves a large NH3 production of 24.6 μg h−1 mgcat.−1 and a high faradaic efficiency of 8.2% at −0.5 V vs. the reversible hydrogen electrode. The experimental results demonstrate that the surface oxygen vacancies are the main catalytic sites for NRR. Introducing Y3+ into the ZrO2 lattice has a significant effect to increase and stabilize the O-vacancies. Meanwhile, this catalyst displays remarkable stability and durability for NRR, showing negligible change after 7 days reaction, which is better than most reported NRR electrocatalysts. Moreover, an in situ electrochemical quartz-crystal microbalance (EQCM) was applied in the NRR field for the first time and was successfully combined with density functional theory (DFT) calculations to reveal the deactivation mechanism.

Long-term electrocatalytic N2 fixation by MOF-derived Y-stabilized ZrO2: insight into the deactivation mechanism

Simultaneously regulating the physical properties and chemical environment of interlayer is a critical need for enhancing the capacity and stability of layered electrode materials in energy and env...

Mingyuan Wang

Papers

Long-term electrocatalytic N2 fixation by MOF-derived Y-stabilized ZrO2: insight into the deactivation mechanism

Enhanced Desalination Capacity and Stability of Alkylamine-Modified Na0.71CoO2 for Capacitive Deionization