Electrocatalytic Nitrogen Reduction to Ammonia Using TiO₂-Supported Cu₄Cl₄(PPh₃)₄ and Ag₄Cl₄(PPh₃)₄ Nanoclusters

The electrocatalytic nitrogen reduction reaction (ENRR) offers a sustainable and promising approach for synthesizing ammonia under ambient conditions, providing an alternative to conventional industrial processes. However, challenges such as the inherent inertness of N₂ and the competing hydrogen evolution reaction (HER) in aqueous electrolytes hinder ammonia yield and Faradaic efficiencies. This research use TiO₂-supported Cu₄Cl₄(PPh₃)₄ and Ag₄Cl₄(PPh₃)₄ nanoclusters (NCs) with quasi-cubic M₄Cl₄ cores (M = Ag or Cu) for ENRR investigations. The results reveal that TiO₂-supported Cu₄Cl₄(PPh₃)₄ NCs achieved an ammonia yield of 4.25 μg·h^-1·cm^-2 with a Faradaic efficiency (FE) of 53.0% at -0.9 V vs RHE. In contrast, TiO₂-supported Ag₄Cl₄(PPh₃)₄ NCs produced a yield of 3.60 μg·h^-1·cm^-2 and an FE of 51.39% at -0.8 V vs RHE. Both NCs on the TiO₂ support demonstrated superior performance compared to their unsupported counterparts, underscoring the critical role of TiO₂ in improving electron transfer and fostering synergistic effects, thereby boosting catalytic activity. This research offers important insights into the design of supported NCs as high-performance catalysts, advancing the development of environmentally sustainable and energy-efficient approaches for ammonia production.