Construction of CoP/TiO2 nanoarray for enhanced electrochemical nitrate reduction to ammonia

Electrochemical nitrate reduction reaction (NO3RR) affords a promising approach for maintaining the balance of the global nitrogen cycle while realizing a sustainable route of ambient ammonia synthesis. Herein, it is evidenced that the electrocatalytic NO3RR activity of CoP can be effectively enhanced by constructing a p-n heterojunction of CoP/TiO2 nanoarray on titanium plate (CoP/TiO2@TP). The p-n heterojunction formed in CoP/TiO2 can establish a built-in electric field due to the difference in their Fermi levels, further accelerating the electrons transport. Benefiting from the interactions of heterostructure, such CoP/TiO2@TP attains an excellent Faradaic efficiency of 95.0% and a large NH3 yield as high as 499.8 μmol h−1 cm−2, which is superior to CoP@TP and TiO2@TP. Moreover, theoretical calculations further reveal that the p-n heterostructure can induce charge redistribution of CoP and TiO2, and optimize the adsorptive free energy of intermediates.