pH-dependent Electrolyte Manipulation in Nitrate Electroreduction to Ammonia

Abstract

Ammonia synthesis serves as a fundamental component of modern agriculture and the chemical sector, playing an essential role in supporting global food security and diverse industrial processes. However, the conventional Haber-Bosch process is highly energy-intensive and contributes significantly to environmental pollution. In response, electrocatalytic nitrate reduction has gained attention as an environmentally sustainable alternative route for generating ammonia. This method facilitates the conversion of nitrate (a common pollutant) into valuable ammonia, thus aligning the goals of sustainable ammonia production and environmental remediation. However, current research predominantly focuses on catalyst design while generally overlooking the critical role of electrolyte pH, resulting in limited adaptability of catalysts under varying pH conditions and unclear mechanisms. To bridge this gap, we propose a synergistic strategy integrating electrolyte pH regulation with advanced catalyst design. We systematically address two major challenges: dissolution issues and competition with hydrogen evolution reactions under acidic conditions, alongside sluggish reaction kinetics due to insufficient reactant supply in neutral or alkaline media. Our approach customizes the local reaction environment by modulating electron donors, employing metal-organic framework materials, and inducing catalyst restructuring. Finally, we propose a closed-loop management scheme suitable for distributed ammonia production and environmental remediation, alongside a design strategy for constructing pH-universal catalyst systems.