Ni2P nanosheet array for high-efficiency electrohydrogenation of nitrite to ammonia at ambient conditions

Ammonia (NH3) plays an important role in agriculture and industry. The industry-scale production mainly depends on the Haber-Bosch process suffering from issues of environment pollution and energy consumption. Electrochemical reduction can degrade nitrite (NO2-) pollutants in the environment and convert it into more valuable NH3. Here, Ni2P nanosheet array on nickel foam is proposed as a 3D electrocatalyst for high-efficiency electrohydrogenation of NO2- to NH3 under ambient reaction conditions. When tested in 0.1 M phosphate buffer saline with 200 ppm NO2-, such Ni2P/NF is able to obtain a large NH3 yield rate of 2692.2 +/- 92.1 mu g h(-1) cm(-2) (3282.9 +/- 112.3 mu g h(-1) mg(cat.)(-1)), a high Faradic efficiency of 90.2 +/- 3.0%, and selectivity of 87.0 +/- 1.7% at -0.3 V versus a reversible hydrogen electrode. After 10 h of electrocatalytic reduction, the conversion rate of NO2- achieves near 100%. The catalytic mechanism is further investigated by density functional theory calculations. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Ammonia plays a crucial role in agriculture and industry, but its traditional production methods suffer from environmental pollution and high energy consumption. This study introduces a highly efficient electrocatalyst that can convert nitrite into ammonia at room temperature, achieving high yield rates and selectivity.