Kijung Yong

Ammonia electrolysis presents a promising strategy for low‐voltage hydrogen production; however, its advancement is impeded by limitations in electrocatalyst performance due to sluggish reaction kinetics and deactivation caused by strongly adsorbed nitrogen‐containing intermediates. In this study, a photodeposited Pt on tungsten suboxide (WO _x ) nanowires (Pt–WO _x (P)) is introduced as a bifunctional electrocatalyst for ammonia electrolysis. The photodeposition induces strong metal–support interaction, resulting in robust interfacial bonding between Pt and WO _x and facilitating electron transfer from WO _x to Pt. ATR‐SEIRAS (attenuated total reflection‐surface enhanced infrared absorption spectroscopy) identifies the Gerischer–Mauerer (G–M) mechanism through absorbance peaks corresponding to NH ₂ and N _x H _y (x = 1–2) and reveals effective suppression of NO _x poisoning on Pt–WO _x (P). DFT confirms the electronic modulation of Pt significantly lowers the energy barrier of the rate‐determining step (RDS) for the conversion of *NH ₂ to *NH by enhancing hydrogen bonding of *NH and *OH. As a result, Pt–WO _x (P) exhibits outstanding AOR activity, achieving a high peak current density of 49.69 mA cm ⁻² . Furthermore, it demonstrates remarkable stability for over 120 h during ammonia electrolysis. In an MEA‐based flow cell, Pt–WO _x (P) delivers current densities exceeding 500 mA cm ⁻² , underscoring its potential as a bifunctional catalyst for ammonia electrolysis applications.

Lithium‐mediated nitrogen reduction reaction (Li‐NRR) offers a promising alternative to the energy‐intensive Haber–Bosch process for ammonia (NH ₃ ) synthesis, enabling renewable‐powered NH ₃ production. However, this technology faces multiple challenges in terms of Faradaic efficiency (FE), energy efficiency (EE), stability and scalability. These problems arise from a variety of causes, but they have one thing in common: they can be improved by uniform deposition of lithium (Li). Therefore, promoting uniform Li plating could serve as a key breakthrough in addressing these issues. This review highlights various studies focusing on the issues associated with Li‐NRR and proposes ideas based on previously reported research on Li metal battery (LMB) systems, which exhibit similarities with the Li‐NRR systems with respect to Li plating and the formation of a solid‐electrolyte interphase (SEI). Effective cross‐pollination of various methods, including electrode modifications, solvation control of Li ⁺ , and application of additives, are introduced. Elaboration of correspondences between Li‐NRR and LMB systems suggests an efficient research strategy for advancing the Li‐NRR field. This review underscores the synergistic potential of hybrid strategies for addressing the critical challenges related to Li‐NRR and provides future research directions and possibilities in this field, which would eventually accelerate progress toward sustainable green NH ₃ production.

Liquid-solid triboelectric nanogenerators (L-S TENGs) have emerged as a promising technology for sustainable energy harvesting and self-powered sensing. By leveraging interactions at liquid-solid interfaces, L-S TENGs efficiently convert low-frequency mechanical energy from various water sources─such as raindrops, waves, and flowing streams─to usable electrical energy. Compared to conventional solid-solid TENGs, L-S TENGs offer superior durability, flexibility, and cost-efficiency. Recent innovations have expanded their functionality beyond energy generation, enabling integration into self-powered sensing systems. These L-S triboelectric nanogenerator-based sensors (TENS) utilize the triboelectric output signal as an intrinsic sensing mechanism, removing external power sources and allowing fully autonomous operation. The sensing capabilities of L-S TENGs can be finely tuned by modifying the physical and chemical properties of the liquid medium or by incorporating smart materials into the solid interface. These materials can respond dynamically to external stimuli such as temperature, light, or magnetic fields, enabling an adaptive sensing performance. This perspective explores the fundamental principles, design strategies, and broad application potential of L-S TENS. It also discusses current challenges and outlines future directions for advancing these systems into multifunctional, energy-autonomous sensing platforms.

Ammonia is a widely produced chemical globally, primarily used in fertilizers and chemical products. Recently, it has gained attention as a green hydrogen carrier due to its high hydrogen content and energy density. However, the conventional Haber‐Bosch process for ammonia synthesis is energy‐intensive, requiring high temperatures and pressures. Also, it is a significant source of CO₂ emissions. To address these environmental concerns, the electrochemical nitrate reduction reaction (NO₃RR) has emerged as a promising approach for green ammonia production, utilizing nitrate from wastewater and renewable energy sources. While most previous research focuses on cathodic ammonia production, it needs to emphasize the importance of optimizing anodic reactions in NO₃RR systems to reduce energy consumption and improve efficiency. The conventional oxygen evolution reaction (OER), typically coupled with NO₃RR, is kinetically slow and requires a high standard potential. Therefore, alternative anodic reactions with lower standard potentials not only save energy but also yield valuable byproducts. Furthermore, coupling NO₃RR with anodic reactions like zinc oxidation allows for power generation, where a positive cell potential indicates spontaneous reactions. This dual approach, energy saving and generation, opens new pathways for sustainable ammonia production, reducing overall energy demands while supporting the shift toward green ammonia systems.

Hydrogen has been proposed as a clean energy source to replace fossil fuels. The hydrogen economy encompasses the production, storage, transport, and use of hydrogen. Among the various potential hydrogen carriers, ammonia is considered an efficient and economical option due to its established infrastructure for production, storage, and transport. In this ammonia value chain, ammonia decomposition enables the efficient and sustainable production of carbon‐free hydrogen. Recently, Co has gained attention as an active metal for thermal ammonia decomposition due to its excellent catalytic performance and cost‐effectiveness. This review presents current developments in supported and unsupported Co‐based catalysts for ammonia decomposition. Key strategies to enhance the hydrogen formation rate include optimizing the Co precursor and synthesis methods, incorporating a second active metal and promoters, tuning the physical properties of the catalyst, and doping heteroatoms into the support. Practical considerations for the preparation of Co‐based catalysts are also outlined. This review provides valuable insights into the development of advanced Co‐based catalysts for ammonia decomposition, with the aim of guiding future research toward highly efficient, cost‐effective, and scalable hydrogen production solutions.

The lithium‐mediated nitrogen reduction reaction (Li‐NRR) is a promising green alternative to the Haber–Bosch process for ammonia synthesis. The solid electrolyte interphase (SEI) is crucial for high efficiency and stability, as it regulates reactant diffusion and suppresses side reactions. The SEI properties are greatly influenced by the Li ⁺ ion solvation structure, which is controllable through electrolyte engineering. Although anion‐derived SEI enhances selectivity and stability, it has typically been engineered using high‐concentration electrolytes (HCEs), which face mass transfer, viscosity, and cost issues. In this study, a localized high‐concentration electrolyte (LHCE) in the Li‐NRR is first introduced, enabling the formation of anion‐derived SEI in a low‐concentration electrolyte (LCE) by enhancing the Li–anion coordination using an antisolvent. Among various antisolvents, 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether (TTE) achieves the highest ammonia Faradaic efficiency (73.6 ± 2.5%), more than double that of the LCE (34.3 ± 2.8%) and exceeding the HCE (56.0 ± 2.8%). Systematic calculations and experimental analyses show that the LHCE exhibits anion‐rich solvation structures and forms thin, inorganic SEI. Moreover, the LHCE has advantages of low viscosity and high N ₂ solubility, which facilitate mass transport. This study suggests the application of LHCE as an effective electrolyte engineering strategy to enhance the Li‐NRR efficiency.