Oxygen-Vacancy-Rich Cu₂O Hollow Nanocubes for Nitrate Electroreduction Reaction to Ammonia in a Neutral Electrolyte

The electrocatalytic nitrate reduction reaction (NO₃^--ERR) to ammonia (NH₃) is a promising strategy for NH₃ production. Cu-based nanomaterials have been regarded as a kind of effective NO₃^--ERR catalysts. In this work, high-quality hollow Cu₂O nanocubes (Cu₂O h-NCs) are facilely synthesized by a simple one-step reduction method. The as-prepared Cu₂O h-NCs reveal high selectivity and activity for NO₃^--ERR, which is ascribed to abundant oxygen vacancies, high surface area, hollow architecture, low mass transfer resistance, and strong adsorbing ability toward NO₃^-. In fact, Cu₂O h-NCs can achieve a Faradic efficiency of 92.9% and an NH₃ yield of 56.2 mg h^-1 mg_cat^-1 for NH₃ production at -0.85 V (vs RHE) potential, which exceeds those of other transition-metal-based NO₃^--ERR electrocatalysts.