Influence of Cu2O Precursor Surface Orientation on Catalytic Performance and Product Selectivity in Nitrate Reduction Reactions.

Oxide-derived copper (OD-Cu) has attracted considerable attention due to its exceptional electrocatalytic performance toward various reactions, including the reduction of nitrate (NO3-) to ammonia (NH3). Furthermore, numerous techniques have been developed to synthesize copper oxides with well-defined surface orientations. However, the relationship between the surface orientation of the precursor and the NO3- reduction performance of the resulting OD-Cu catalyst remains unclear. In this study, two types of OD-Cu electrodes, prepared by reducing copper oxide (Cu2O) with exposed (100) and (111) facets grown on Cu substrates, were employed for NO3- reduction. The OD-Cu catalyst derived from Cu2O (111) exhibited a lower overpotential for initiating NO3- reduction and achieved a higher current density compared to the catalyst derived from Cu2O(100). Conversely, the catalyst prepared from Cu2O(100) demonstrated superior Faradaic efficiency for NH3 production. These differences are attributed to variations in the preferential reaction steps of NO3- reduction on each catalyst.