pH effect on electrocatalytic nitrate reduction in high-salinity wastewater and control strategies

Nitrate contamination in high-salinity wastewater poses severe threats to ecosystems and human health amid escalating industrial activities. Electrocatalytic nitrate reduction reaction (ENO₃RR) emerges as an eco-friendly and efficient remediation approach, yet its performance is intricately modulated by pH in saline environments. Despite advancements, prior reviews have overlooked the combined effects of pH and high-salinity, lacking integrated mechanistic insights and practical strategies for overcoming local pH gradients and ion interferences. This review innovatively dissects pH’s regulatory roles through a funnel framework, proposing novel interfacial engineering paradigms to enhance ENO₃RR efficiency. Firstly, it elucidates pH impacts on reduction kinetics, product selectivity toward ammonia, and catalyst stability under intensified salinity effects. Subsequently, it delineates mechanistic pathways, including competitive ion adsorption, proton transfer dynamics, and double-layer restructuring that amplify local microenvironments. Furthermore, advanced control strategies are summarized, encompassing hierarchical catalyst designs for micro-level pH modulation and reactor optimizations like bipolar membranes for macro-scale stability. By bridging fundamental mechanisms with actionable methodologies, this work furnishes a comprehensive roadmap for developing resilient ENO₃RR systems, paving the way for scalable applications in challenging wastewater treatment scenarios.