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 mgcat-1 for NH3 production at -0.85 V (vs RHE) potential, which exceeds those of other transition-metal-based NO3--ERR electrocatalysts.