Photoactive Earth-Abundant Iron Pyrite Catalysts for Electrocatalytic Nitrogen Reduction Reaction
Chia-Che Chang, Shin-Ren Li, Hung-Lung Chou,* Yi-Cheng Lee, Shivaraj Patil, Ying-Sheng Lin, Chun-Chih Chang, Yuan Jay Chang and Di-Yan Wang*
The generation of ammonia, hydrogen production and nitrogen purification are considered as energy intensive processes accompanied with large amount of CO2 emission. The electrochemical method assisted by photo energy has been widely utilized for the chemical energy conversion. In this work, the earth-abundant iron pyrite (FeS2) nanocrystals grown on carbon fiber paper (FeS2/CFP) was found to be an electrochemical and photoactive catalysts for nitrogen reduction reaction (NRR) under ambient temperature and pressure. The electrochemical results revealed that FeS2/CFP achieved a high Faradaic efficiency (FE) ~14.14% and NH3 yield rate~ 0.096 mg/min at −0.6 V versus RHE electrode in 0.25 M LiClO4. During proceeding electrochemical catalytic reaction, the crystal structure of FeS2/CFP remained cubic pyrite phase analyzed by in-situ XRD measurement. Also, With near infrared laser irradiation (808 nm), NH3 yield rate of FeS2/CFP catalyst can be slightly improved to (0.1 mg/min) with high FE of 14.57%. Furthermore, density functional theoretical (DFT) calculations demonstrated that N2 molecule had strong chemical adsorption energy on the iron atom of FeS2. Overall, the iron pyrite-based materials have proven to be a potential electrocatalyst with photoactive behavior for ammonia production in practical applications.