Advances in Layered Double Hydroxide (LDH)-Based Materials for Electrocatalytic Nitrogen Reduction to Ammonia: A Comprehensive Review

Nitrogen (N2), constituting the majority of Earth’s atmosphere, remains indispensable for biological systems and underpins modern agriculture and industry. Traditionally, the Haber–Bosch process has been essential for synthesizing ammonia (NH3) from N2 under high temperature and pressure, but it contributes significantly to global CO2 emissions. Recently, carbon-free electrocatalytic nitrogen reduction (e-NRR) has emerged as a promising, eco-friendly, and cost-effective approach for green NH3 production under mild conditions using renewable energy, offering a sustainable alternative to the fossil fuel dependent Haber–Bosch process. This work explores NRR by contrasting the limitations of Haber–Bosch with the advantages of electrocatalysis. Despite progress, electrochemical N2 reduction to NH3 production remains challenging due to low activity, poor selectivity, stability, efficiency, and detection issues. Developing efficient e-NRR electrocatalysts is crucial to enhance activity, suppress hydrogen evolution reaction (HER), boost NH3 yield, and improve Faradaic efficiency. This review highlights the role of layered double hydroxide (LDH) catalysts in e-NRR, summarizing the fundamental process, reaction pathways, and synthesis strategies. Ammonia detection methods, key metrics, and potential contamination issues are compared to inform standard NRR measurement protocols. Lastly, we summarize key findings to synthesize and improve LDH electrocatalysts for NH3 production and a sustainable, carbon-free N2 economy.